128-417: Hair loss , also known as alopecia or baldness , refers to a loss of hair from part of the head or body. Typically at least the head is involved. The severity of hair loss can vary from a small area to the entire body. Inflammation or scarring is not usually present. Hair loss in some people causes psychological distress . Common types include male- or female-pattern hair loss , alopecia areata , and
256-548: A brown-haired person has 110,000, a black-haired person has 100,000, and a redhead has 90,000. Hair growth stops after a human's death. Visible growth of hair on the dead body happens only because of skin drying out due to water loss. The world record for longest hair on a living person stands with Smita Srivastava of Uttar Pradesh, India . At 7 feet and 9 inches long, she broke a Guinness World Record in November 2023, having grown her hair for 32 years. Hair exists in
384-447: A loss-of-function mutation in the gene encoding 5α-reductase type 2 , the major enzyme responsible for the production of DHT in the body. It is characterized by a defective and non-functional 5α-reductase type 2 enzyme and a partial but majority loss of DHT production in the body. In the condition, circulating testosterone levels are within or slightly above the normal male range, but DHT levels are low (around 30% of normal), and
512-483: A shaved head . The general public became more accepting of men with shaved heads in the early 1950s, when Russian-American actor Yul Brynner began sporting the look; the resulting phenomenon inspired many of his male fans to shave their heads. Male celebrities then continued to bring mainstream popularity to shaved heads, including athletes such as Michael Jordan and Zinedine Zidane and actors such as Dwayne Johnson , Ben Kingsley , and Jason Statham . Female baldness
640-914: A cotton thread, but is not stiff or rough. It is neither fine nor coarse. Thick strands whose shed strands usually are easily identified. Coarse hair feels hard and wiry. Hair is mainly composed of keratin proteins and keratin-associated proteins (KRTAPs). The human genome encodes 54 different keratin proteins which are present in various amounts in hair. Similarly, humans encode more than 100 different KRTAPs which crosslink keratins in hair. The content of KRTAPs ranges from less than 3% in human hair to 30–40% in echidna quill. Many mammals have fur and other hairs that serve different functions. Hair provides thermal regulation and camouflage for many animals; for others it provides signals to other animals such as warnings, mating, or other communicative displays; and for some animals hair provides defensive functions and, rarely, even offensive protection. Hair also has
768-529: A few weeks, but regrows permanently within months. Hypothermia caps may be used to prevent hair loss during some kinds of chemotherapy , specifically, when taxanes or anthracyclines are administered. It is not recommended to be used when cancer is present in the skin of the scalp or for lymphoma or leukemia. There are generally only minor side effects from scalp cooling given during chemotherapy. Instead of attempting to conceal their hair loss, some people embrace it by either doing nothing about it or sporting
896-435: A flat cross-section, while people of mostly European or Middle Eastern ancestry tend to have hair with a diameter of 70–100 μm and an oval cross-section, and people of mostly Asian or Native American ancestry tend to have hair with a diameter of 90–120 μm and a round cross-section. There are roughly two million small, tubular glands and sweat glands that produce watery fluids that cool the body by evaporation. The glands at
1024-673: A measurement that was once the basis of drug tests used to detect steroid use. However, DHT use can still be detected by other means which are now universal in athletic drug tests, such as metabolite analysis. In 2004, Richard Auchus, in a review published in Trends in Endocrinology and Metabolism coined the term "backdoor pathway" as a metabolic route to DHT that: 1) bypasses conventional intermediates androstenedione and testosterone; 2) involves 5α-reduction of 21-carbon (C21) pregnanes to 19-carbon (C19) androstanes ; and 3) involves
1152-439: A medication, see the androstanolone article. DHT is biologically important for sexual differentiation of the male genitalia during embryogenesis , maturation of the penis and scrotum at puberty , growth of facial , body , and pubic hair , and development and maintenance of the prostate gland and seminal vesicles . It is produced from the less potent testosterone by the enzyme 5α-reductase in select tissues, and
1280-571: A modest reduction of only 15% for finasteride. However, MK-386 failed to show significant effectiveness in a subsequent clinical study for the treatment of acne. DHT is a potent agonist of the AR, and is in fact the most potent known endogenous ligand of the receptor. It has an affinity (K d ) of 0.25 to 0.5 nM for the human AR, which is about 2- to 3-fold higher than that of testosterone (K d = 0.4 to 1.0 nM) and 15–30 times higher than that of adrenal androgens . In addition,
1408-508: A near-functional penis and descent of the testes ), voice deepening , typical male musculoskeletal development, and no menstruation , breast development , or other signs of feminization that occur during female puberty. In addition, normal libido and spontaneous erections develop, they usually show a sexual preference for females, and almost all develop a male gender identity . Nonetheless, males with 5α-reductase type 2 deficiency exhibit signs of continued undervirilization in
SECTION 10
#17327726040501536-429: A number of androgen-dependent conditions including hair conditions like hirsutism (excessive facial/body hair growth) and pattern hair loss (androgenic alopecia or pattern baldness) and prostate diseases such as benign prostatic hyperplasia (BPH) and prostate cancer . 5α-Reductase inhibitors , which prevent DHT synthesis, are effective in the prevention and treatment of these conditions. Androgen deprivation
1664-588: A number of domains. Facial hair was absent or sparse in a relatively large group of Dominican males with the condition, known as the Güevedoces . However, more facial hair has been observed in patients with the disorder from other parts of the world, although facial hair was still reduced relative to that of other men in the same communities. The divergent findings may reflect racial differences in androgen-dependent hair growth. A female pattern of androgenic hair growth , with terminal hair largely restricted to
1792-402: A partially unfused, labia -like scrotum , and a blind-ending, shallow vaginal pouch . Due to their lack of conspicuous male genitalia , genetic males with the condition are typically raised as girls. At the time of puberty however, they develop striking phenotypically masculine secondary sexual characteristics including partial virilization of the genitals (enlargement of the phallus into
1920-455: A quarter of women. About 2% of people develop alopecia areata at some point in time. Baldness is the partial or complete lack of hair growth, and part of the wider topic of "hair thinning". The degree and pattern of baldness varies, but its most common cause is androgenic hair loss , alopecia androgenetica , or alopecia seborrheica , with the last term primarily used in Europe. Hypotrichosis
2048-441: A receding hairline and/or a thinning crown, through to a horseshoe-shaped ring of hair around the head and on to total baldness. In almost all cases of thinning, and especially in cases of severe hair loss, it is recommended to seek advice from a doctor or dermatologist . Many types of thinning have an underlying genetic or health-related cause, which a qualified professional will be able to diagnose. One method of hiding hair loss
2176-447: A sensory function, extending the sense of touch beyond the surface of the skin. Guard hairs give warnings that may trigger a recoiling reaction. While humans have developed clothing and other means of keeping warm, the hair found on the head serves primarily as a source of heat insulation and cooling (when sweat evaporates from soaked hair) as well as protection from ultra-violet radiation exposure. The function of hair in other locations
2304-629: A short resting phase ( telogen ). At the end of the resting phase, the hair falls out (exogen) and a new hair starts growing in the follicle, beginning the cycle again. Normally, about 40 (0–78 in men) hairs reach the end of their resting phase each day and fall out. When more than 100 hairs fall out per day, clinical hair loss ( telogen effluvium ) may occur. A disruption of the growing phase causes abnormal loss of anagen hairs ( anagen effluvium ). Because they are not usually associated with an increased loss rate, male-pattern and female-pattern hair loss do not generally require testing. If hair loss occurs in
2432-855: A sustained cellular response to the DNA damage that accumulates in renewing stem cells during aging. This damage response involves the proteolysis of type XVII collagen by neutrophil elastase in response to DNA damage in hair follicle stem cells. Proteolysis of collagen leads to elimination of the damaged cells and, consequently, to terminal hair follicle miniaturization. In June 2022 the University of California, Irvine announced that researchers have discovered that hedgehog signaling in murine fibroblasts induces new hair growth and hair multiplication while hedgehog activation increases fibroblast heterogeneity and drives new cell states. A new signaling molecule called SCUBE3 potently stimulates hair growth and may offer
2560-476: A therapeutic treatment for androgenetic alopecia. The term alopecia ( / ˌ æ l ə ˈ p iː ʃ i ə / ) is from the Classical Greek ἀλώπηξ , alōpēx , meaning "fox". The origin of this usage is because this animal sheds its coat twice a year, or because in ancient Greece foxes often lost hair because of mange . Hair Hair is a protein filament that grows from follicles found in
2688-460: A thinning of hair known as telogen effluvium . The cause of male-pattern hair loss is a combination of genetics and male hormones ; the cause of female pattern hair loss is unclear; the cause of alopecia areata is autoimmune ; and the cause of telogen effluvium is typically a physically or psychologically stressful event. Telogen effluvium is very common following pregnancy . Less common causes of hair loss without inflammation or scarring include
SECTION 20
#17327726040502816-400: A variety of textures. Three main aspects of hair texture are the curl pattern, volume, and consistency. All mammalian hair is composed of keratin , so the make-up of hair follicles is not the source of varying hair patterns. There are a range of theories pertaining to the curl patterns of hair. Scientists have come to believe that the shape of the hair shaft has an effect on the curliness of
2944-589: A young man with no family history, drug use could be the cause. There are two types of identification tests for female pattern baldness: the Ludwig Scale and the Savin Scale. Both track the progress of diffused thinning, which typically begins on the crown of the head behind the hairline, and becomes gradually more pronounced. For male pattern baldness, the Hamilton–Norwood scale tracks the progress of
3072-805: Is excreted in the urine as metabolites , such as conjugates of 3α-androstanediol and androsterone . Ranges for circulating total DHT levels tested with HPLC–MS/MS and reported by LabCorp are as follows: Ranges for circulating free DHT levels tested with HPLC–MS/MS and equilibrium dialysis and reported by LabCorp are as follows: Other studies and labs assessing circulating total DHT levels with LC–MS/MS have reported ranges of 11–95 ng/dL (0.38–3.27 nmol/L) in adult men, 14–77 ng/dL (0.47–2.65 nmol/L) for healthy adult men (age 18–59 years), 23–102 ng/dL (0.8–3.5 nmol/L) for community-dwelling adult men (age <65 years), and 14–92 ng/dL (0.49–3.2 nmol/L) for healthy older men (age 71–87 years). In
3200-535: Is a complex issue. Hair is considered an essential part of overall identity: especially for women, for whom it often represents femininity and attractiveness. Men typically associate a full head of hair with youth and vigor. People experiencing hair thinning often find themselves in a situation where their physical appearance is at odds with their own self-image and commonly worry that they appear older than they are or less attractive to others. Psychological problems due to baldness, if present, are typically most severe at
3328-451: Is a condition of abnormal hair patterns, predominantly loss or reduction. It occurs, most frequently, by the growth of vellus hair in areas of the body that normally produce terminal hair . Typically, the individual's hair growth is normal after birth, but shortly thereafter the hair is shed and replaced with sparse, abnormal hair growth. The new hair is typically fine, short and brittle, and may lack pigmentation. Baldness may be present by
3456-423: Is a method which classifies the hair by curl pattern, hair-strand thickness and overall hair volume. Curliness Strands Thin strands that sometimes are almost translucent when held up to the light. Shed strands can be hard to see even against a contrasting background. Fine hair is difficult to feel or it feels like an ultra-fine strand of silk. Strands are neither fine nor coarse. Medium hair feels like
3584-499: Is a therapeutic approach to prostate cancer that can be implemented by castration to eliminate gonadal testosterone as a precursor to DHT, but metastatic tumors may then develop into castration-resistant prostate cancer (CRPC). Although castration results in 90-95% decrease of serum testosterone, DHT in the prostate is only decreased by 50%, supporting the notion that the prostate expresses necessary enzymes (including 5α-reductase) to produce DHT without testicular testosterone, that outline
3712-496: Is a trait that may be associated with neoteny . Primates are relatively hairless compared to other mammals, and Hominini such as chimpanzees, have less dense hair than would be expected given their body size for a primate. Evolutionary biologists suggest that the genus Homo arose in East Africa approximately 2 million years ago. Part of this evolution was the development of endurance running and venturing out during
3840-456: Is an endogenous androgen sex steroid and hormone primarily involved in the growth and repair of the prostate and the penis , as well as the production of sebum and body hair composition. The enzyme 5α-reductase catalyzes the formation of DHT from testosterone in certain tissues including the prostate gland , seminal vesicles , epididymides , skin , hair follicles , liver , and brain . This enzyme mediates reduction of
3968-493: Is available in pharmaceutical formulations for medical use as an androgen or anabolic–androgenic steroid (AAS). It is used mainly in the treatment of male hypogonadism . When used as a medication, dihydrotestosterone is referred to as androstanolone ( INN Tooltip International Nonproprietary Name ) or as stanolone ( BAN Tooltip British Approved Name ), and is sold under brand names such as Andractim among others. The availability of pharmaceutical DHT
Hair loss - Misplaced Pages Continue
4096-487: Is believed to be due to a combination of genetics and the male hormone dihydrotestosterone . The cause in female pattern hair loss remains unclear. Hair loss often follows childbirth in the postpartum period without causing baldness. During pregnancy, the hair is thicker owing to increased circulating estrogens . Approximately three months after giving birth (typically between 2 and 5 months), estrogen levels drop and hair loss occurs, often particularly noticeably around
4224-484: Is bound 49.7% to sex hormone-binding globulin (SHBG), 39.2% to albumin , and 0.22% to corticosteroid-binding globulin (CBG), while in premenopausal women, DHT is bound 78.1–78.4% to SHBG, 21.0–21.3% to albumin, and 0.12% to CBG. In late pregnancy, only 0.07% of DHT is unbound in women; 97.8% is bound to SHBG while 2.15% is bound to albumin and 0.04% is bound to CBG. DHT has higher affinity for SHBG than does testosterone, estradiol, or any other steroid hormone. DHT
4352-438: Is cognate with terms such as Old Norse and Norwegian : fax . Each strand of hair is made up of the medulla , cortex , and cuticle . The innermost region, the medulla , is an open and unstructured region that is not always present. The highly structural and organized cortex , or second of three layers of the hair, is the primary source of mechanical strength and water uptake. The cortex contains melanin , which colors
4480-419: Is debated. Hats and coats are still required while doing outdoor activities in cold weather to prevent frostbite and hypothermia , but the hair on the human body does help to keep the internal temperature regulated. When the body is too cold, the arrector pili muscles found attached to hair follicles stand up, causing the hair in these follicles to do the same. These hairs then form a heat-trapping layer above
4608-448: Is in accordance with the fact that sebum secretion appears to be entirely under the control of 5α-reductase type 1. 5α-Reductase inhibitors like finasteride and dutasteride inhibit 5α-reductase type 2 and/or other isoforms and are able to decrease circulating DHT levels by 65 to 98% depending on the 5α-reductase inhibitor in question. As such, similarly to the case of 5α-reductase type 2 deficiency, they provide useful insights in
4736-593: Is inactivated in the liver and extrahepatic tissues like the skin into 3α-androstanediol and 3β-androstanediol by the enzymes 3α-hydroxysteroid dehydrogenase and 3β-hydroxysteroid dehydrogenase , respectively. These metabolites are in turn converted, respectively, into androsterone and epiandrosterone , then conjugated (via glucuronidation and/or sulfation ), released into circulation , and excreted in urine . Unlike testosterone, DHT cannot be aromatized into an estrogen like estradiol, and for this reason, has no propensity for estrogenic effects. DHT
4864-469: Is interpreted in the neocortex , a section of the brain that expanded markedly in animals like Morganucodon and Hadrocodium . The more advanced therapsids could have had a combination of naked skin, whiskers , and scutes . A full pelage likely did not evolve until the therapsid-mammal transition. The more advanced, smaller therapsids could have had a combination of hair and scutes, a combination still found in some modern mammals, such as rodents and
4992-551: Is limited; it is not available in the United States or Canada , but is available in certain European countries. The available formulations of DHT include buccal or sublingual tablets , topical gels , and, as esters in oil , injectables like androstanolone propionate and androstanolone valerate . DHT has been used as a performance enhancing drug , specifically as an alternative to testosterone , as it
5120-478: Is more complex, since not all hair grows at once. Scalp hair was reported to grow between 0.6 cm and 3.36 cm per month. The growth rate of scalp hair somewhat depends on age (hair tends to grow more slowly with age), sex, and ethnicity. Thicker hair (>60 μm) grows generally faster (11.4 mm per month) than thinner (20-30 μm) hair (7.6 mm per month). It was previously thought that Caucasian hair grew more quickly than Asian hair and that
5248-455: Is not just one method to discovering one's hair type. Additionally it is possible, and quite normal to have more than one kind of hair type, for instance having a mixture of both type 3a & 3b curls. The Andre Walker Hair Typing System is the most widely used system to classify hair. The system was created by Oprah Winfrey 's hairstylist, Andre Walker . According to this system there are four types of hair: straight, wavy, curly, kinky. This
Hair loss - Misplaced Pages Continue
5376-575: Is observed in certain brain areas, non-genital skin/hair follicles, testes , and kidneys . SRD5A1 is most highly expressed in non-genital skin/hair follicles, the liver, and certain brain areas, while lower levels are present in the prostate, epididymides, seminal vesicles, genital skin, testes, adrenal glands , and kidneys. In the skin, 5α-reductase is expressed in sebaceous glands , sweat glands , epidermal cells , and hair follicles. Both isoenzymes are expressed in scalp hair follicles, although SRD5A2 predominates in these cells. The SRD5A2 subtype
5504-448: Is often used to indicate a person's personal beliefs or social position, such as their age, gender , or religion . The word "hair" usually refers to two distinct structures: Hair fibers have a structure consisting of several layers, starting from the outside: The word "hair" is derived from Middle English : heer and hêr , in turn derived from Old English : hǽr and hér , with influence from Old Norse : hár . Both
5632-680: Is still viewed as less normal in various parts of the world. Dietary supplements are not typically recommended. There is only one small trial of saw palmetto which shows tentative benefit in those with mild to moderate androgenetic alopecia. There is no evidence for biotin . Evidence for most other alternative medicine remedies is also insufficient. There was no good evidence for ginkgo , aloe vera , ginseng , bergamot , hibiscus , or sophora as of 2011. Many people use unproven treatments to treat hair loss. Egg oil , in Indian, Japanese, Unani (Roghan Baiza Murgh) and Chinese traditional medicine ,
5760-420: Is the comb over , which involves restyling the remaining hair to cover the balding area. It is usually a temporary solution, useful only while the area of hair loss is small. As the hair loss increases, a comb over becomes less effective. Another method is to wear a hat or a hairpiece such as a wig or toupee . The wig is a layer of artificial or natural hair made to resemble a typical hair style. In most cases
5888-434: Is the almost exclusive isoform expressed in the prostate gland. DHT under certain normal and pathological conditions can additionally be produced via a route that does not involve testosterone as an intermediate but instead goes through other intermediates. This route is called the "backdoor pathway". The pathway can start from 17α-hydroxyprogesterone or from progesterone and can be outlined as follows (depending on
6016-409: Is the outer covering. Its complex structure slides as the hair swells and is covered with a single molecular layer of lipid that makes the hair repel water. The diameter of human hair varies from 0.017 to 0.18 millimeters (0.00067 to 0.00709 in). Some of these characteristics in humans' head hair vary by race: people of mostly African ancestry tend to have hair with a diameter of 60–90 μm and
6144-557: Is the primary androgen in the genitals, prostate gland , seminal vesicles , skin , and hair follicles . DHT signals act mainly in an intracrine and paracrine manner in the tissues in which it is produced, playing only a minor role, if any, as a circulating endocrine hormone. Circulating levels of DHT are one-tenth and one-twentieth those of testosterone in terms of total and free concentrations, respectively, whereas local DHT levels may be up to 10 times those of testosterone in tissues with high 5α-reductase expression such as
6272-557: The Upper Permian , shows smooth, hairless skin with what appears to be glandular depressions, though as a semi-aquatic species it might not have been particularly useful to determine the integument of terrestrial species. The oldest undisputed known fossils showing unambiguous imprints of hair are the Callovian (late middle Jurassic ) Castorocauda and several contemporary haramiyidans , both near-mammal cynodonts , giving
6400-441: The anagen , catagen , and telogen phases. Each strand of hair on the human body is at its own stage of development. Once the cycle is complete, it restarts and a new strand of hair begins to form. The growth rate of hair varies from individual to individual depending on their age, genetic predisposition and a number of environmental factors. It is commonly stated that hair grows about 1 cm per month on average; however reality
6528-618: The axillae and lower pubic triangle , is observed in males with the condition. No temporal recession of the hairline or androgenic alopecia (pattern hair loss or baldness) has been observed in any of the cases of 5α-reductase type 2 deficiency that have been reported, whereas this is normally seen to some degree in almost all Caucasian males in their teenage years. Individuals with 5α-reductase type 2 deficiency were initially reported to have no incidence of acne , but subsequent research indicated normal sebum secretion and acne incidence. In genetic males with 5α-reductase type 2 deficiency,
SECTION 50
#17327726040506656-549: The dermis . Hair is one of the defining characteristics of mammals . The human body , apart from areas of glabrous skin, is covered in follicles which produce thick terminal and fine vellus hair . Most common interest in hair is focused on hair growth , hair types, and hair care , but hair is also an important biomaterial primarily composed of protein , notably alpha-keratin . Attitudes towards different forms of hair, such as hairstyles and hair removal , vary widely across different cultures and historical periods, but it
6784-480: The dissociation rate of DHT from the AR is 5-fold slower than that of testosterone. The EC 50 of DHT for activation of the AR is 0.13 nM, which is about 5-fold stronger than that of testosterone (EC 50 = 0.66 nM). In bioassays , DHT has been found to be 2.5- to 10-fold more potent than testosterone. The elimination half-life of DHT in the body (53 minutes) is longer than that of testosterone (34 minutes), and this may account for some of
6912-409: The epidermis called the hair follicle . The bulb of hair consists of fibrous connective tissue, glassy membrane, external root sheath, internal root sheath composed of epithelium stratum ( Henle's layer ) and granular stratum ( Huxley's layer ), cuticle, cortex and medulla. All natural hair colors are the result of two types of hair pigments. Both of these pigments are melanin types, produced inside
7040-526: The epidermis . This process is formally called piloerection , derived from the Latin words 'pilus' ('hair') and 'erectio' ('rising up'), but is more commonly known as 'having goose bumps ' in English. This is more effective in other mammals whose fur fluffs up to create air pockets between hairs that insulate the body from the cold. The opposite actions occur when the body is too warm; the arrector muscles make
7168-436: The estrogen receptor (ER) subtype ERβ . These metabolites may play important roles in the central effects of DHT and by extension testosterone, including their antidepressant , anxiolytic , rewarding / hedonic , anti-stress , and pro-cognitive effects. Much of the biological role of DHT has been elucidated in studies of individuals with congenital 5α-reductase type 2 deficiency , an intersex condition caused by
7296-418: The fiber based on the number, distribution and types of melanin granules. The melanin may be evenly spaced or cluster around the edges of the hair. The shape of the follicle determines the shape of the cortex, and the shape of the fiber is related to how straight or curly the hair is. People with straight hair have round hair fibers. Oval and other shaped fibers are generally more wavy or curly. The cuticle
7424-406: The genitals ( penis , scrotum , clitoris , labia majora ), prostate gland , skin , hair follicles , liver , and brain . Around 5 to 7% of testosterone undergoes 5α-reduction into DHT, and approximately 200 to 300 μg of DHT is synthesized in the body per day. Most DHT is produced in peripheral tissues like the skin and liver, whereas most circulating DHT originates specifically from
7552-509: The hygiene and cosmetology of hair including hair on the scalp , facial hair ( beard and moustache ), pubic hair and other body hair. Hair care routines differ according to an individual's culture and the physical characteristics of one's hair. Hair may be colored, trimmed, shaved, plucked, or otherwise removed with treatments such as waxing, sugaring, and threading. Dihydrotestosterone Dihydrotestosterone ( DHT , 5α-dihydrotestosterone , 5α-DHT , androstanolone or stanolone )
7680-406: The opossum . The high interspecific variability of the size, color, and microstructure of hair often enables the identification of species based on single hair filaments. In varying degrees most mammals have some skin areas without natural hair. On the human body, glabrous skin is found on the ventral portion of the fingers , palms , soles of feet and lips , which are all parts of
7808-437: The prostate gland is rudimentary or absent, and if present, remains small, underdeveloped, and unpalpable throughout life. In addition, neither BPH nor prostate cancer have been reported in these individuals. Genetic males with the condition generally show oligozoospermia due to undescended testes, but spermatogenesis is reported to be normal in those with testes that have descended, and there are case instances of men with
SECTION 60
#17327726040507936-429: The pulling out of hair , certain medications including chemotherapy , HIV/AIDS , hypothyroidism , and malnutrition including iron deficiency . Causes of hair loss that occurs with scarring or inflammation include fungal infection , lupus erythematosus , radiation therapy , and sarcoidosis . Diagnosis of hair loss is partly based on the areas affected. Treatment of pattern hair loss may simply involve accepting
8064-545: The 3α-oxidation of 5α-androstane-3α,17β-diol to DHT. This newly discovered pathway explained how DHT is produced under certain normal and pathological conditions in humans when the classical androgen pathway (via testosterone) cannot fully explain the observed consequences. This review was based on earlier works (published in 2000–2004) by Shaw et al., Wilson et al., and Mahendroo et al., who studied DHT biosynthesis in tammar wallaby pouch young and mice. In 2011, Chang et al. demonstrated that yet another metabolic pathway to DHT
8192-508: The AR and those caused by testosterone's conversion to estradiol and subsequent binding to and activation of ERs. Although DHT cannot be aromatized, it is still transformed into metabolites with significant ER affinity and activity. These are 3α-androstanediol and 3β-androstanediol, which are predominant agonists of the ERβ. DHT is synthesized irreversibly from testosterone by the enzyme 5α-reductase . This occurs in various tissues including
8320-521: The C4-5 double bond of testosterone. DHT may also be synthesized from progesterone and 17α-hydroxyprogesterone via the androgen backdoor pathway in the absence of testosterone. Relative to testosterone, DHT is considerably more potent as an agonist of the androgen receptor (AR). In addition to its role as a natural hormone, DHT has been used as a medication , for instance in the treatment of low testosterone levels in men ; for information on DHT as
8448-465: The EDAR locus, a region of the modern human genome that contributes to hair texture variation among most individuals of East Asian descent, support the hypothesis that (East Asian) straight hair likely developed in this branch of the modern human lineage subsequent to the original expression of tightly coiled natural afro-hair . Specifically, the relevant findings indicate that the EDAR mutation coding for
8576-467: The Old English and Old Norse words derive from Proto-Germanic : * hēran and are related to terms for hair in other Germanic languages such as Swedish : här , Dutch and German : haar , and Old Frisian : her . The now broadly obsolete word "fax" refers specifically to head hair and is found in compounds such as Fairfax and Halifax . It is derived from Old English : feax and
8704-536: The U.S. Food and Drug Administration (FDA) approved Olumiant (baricitinib) for adults with severe alopecia areatal. It is the first FDA approved drug for systemic treatment, or treatment for any area of the body. Hair transplantation is usually carried out under local anesthetic . A surgeon will move healthy hair from the back and sides of the head to areas of thinning. The procedure can take between four and eight hours, and additional sessions can be carried out to make hair even thicker. Transplanted hair falls out within
8832-445: The age as no later than ≈220 ma based on the modern phylogenetic understanding of these clades. More recently, studies on terminal Permian Russian coprolites may suggest that non-mammalian synapsids from that era had fur. If this is the case, these are the oldest hair remnants known, showcasing that fur occurred as far back as the latest Paleozoic . Some modern mammals have a special gland in front of each orbit used to preen
8960-414: The belly and lower tail of a pelycosaur , possibly Haptodus shows the basal synapsid stock bore transverse rows of rectangular scutes , similar to those of a modern crocodile , so the age of acquirement of hair logically could not have been earlier than ≈299 ma, based on the current understanding of the animal's phylogeny. An exceptionally well-preserved skull of Estemmenosuchus , a therapsid from
9088-493: The body most closely associated with interacting with the world around us, as are the labia minora and glans penis . There are four main types of mechanoreceptors in the glabrous skin of humans: Pacinian corpuscles , Meissner's corpuscles , Merkel's discs , and Ruffini corpuscles . The naked mole-rat ( Heterocephalus glaber ) has evolved skin lacking in general, pelagic hair covering, yet has retained long, very sparsely scattered tactile hairs over its body. Glabrousness
9216-646: The case of women, mean circulating DHT levels have been found to be about 9 ng/dL (0.3 nmol/L) in premenopausal women and 3 ng/dL (0.1 nmol/L) in postmenopausal women. There was no variation in DHT levels across the menstrual cycle in premenopausal women, which is in contrast to testosterone (which shows a peak at mid-cycle ). With immunoassay -based techniques, testosterone levels in premenopausal women have been found to be about 40 ng/dL (1.4 nmol/L) and DHT levels about 10 ng/dL (0.34 nmol/L). With radioimmunoassays ,
9344-411: The circulation however, levels of DHT in the prostate gland are approximately 5- to 10-fold higher than those of testosterone. This is due to a more than 90% conversion of testosterone into DHT in the prostate via locally expressed 5α-reductase . Because of this, and because DHT is much more potent as an androgen receptor agonist than testosterone, DHT is the major androgen in the prostate gland. DHT
9472-425: The circulation of cool air onto the scalp. Further, wet Afro-hair does not stick to the neck and scalp unless totally drenched and instead tends to retain its basic springy puffiness because it less easily responds to moisture and sweat than straight hair does. In this sense, the trait may enhance comfort levels in intense equatorial climates more than straight hair (which, on the other hand, tends to naturally fall over
9600-453: The condition of the strand. Fine hair has the smallest circumference, coarse hair has the largest circumference, and medium hair is anywhere between the other two. Coarse hair has a more open cuticle than thin or medium hair causing it to be the most porous. There are various systems that people use to classify their curl patterns. Being knowledgeable of an individual's hair type is a good start to knowing how to take care of one's hair. There
9728-415: The condition successfully fathering children. Unlike males, genetic females with 5α-reductase type 2 deficiency are phenotypically normal. However, similarly to genetic males with the condition, they show reduced body hair growth, including an absence of hair on the arms and legs, slightly decreased axillary hair, and moderately decreased pubic hair. On the other hand, sebum production is normal. This
9856-401: The condition, which can also include shaving one's head . Interventions that can be tried include the medications minoxidil (or finasteride ) and hair transplant surgery . Alopecia areata may be treated by steroid injections in the affected area, but these need to be frequently repeated to be effective. Hair loss is a common problem. Pattern hair loss by age 50 affects about half of men and
9984-418: The conventional pathway of DHT synthesis, the backdoor pathway similarly requires 5α-reductase . Whereas 5α-reduction is the last transformation in the classical androgen pathway, it is the first step in the backdoor pathway. The plasma protein binding of DHT is more than 99%. In men, approximately 0.88% of DHT is unbound and hence free, while in premenopausal women, about 0.47–0.48% is unbound. In men, DHT
10112-442: The difference in their potency. A study of transdermal (patches) DHT and testosterone treatment reported terminal half-lives of 2.83 hours and 1.29 hours, respectively. Unlike other androgens such as testosterone, DHT cannot be converted by the enzyme aromatase into an estrogen like estradiol . Therefore, it is frequently used in research settings to distinguish between the effects of testosterone caused by binding to
10240-506: The ears and neck to a degree that provides slightly enhanced comfort levels in cold climates relative to tightly coiled hair). Further, it is notable that the most pervasive expression of this hair texture can be found in sub-Saharan Africa; a region of the world that abundant genetic and paleo-anthropological evidence suggests, was the relatively recent (≈200,000-year-old) point of origin for modern humanity. In fact, although genetic findings (Tishkoff, 2009) suggest that sub-Saharan Africans are
10368-457: The edges of the eyelid and protects the eye from dirt. The eyelash is to humans, camels, horses, ostriches etc., what whiskers are to cats ; they are used to sense when dirt, dust , or any other potentially harmful object is too close to the eye. The eye reflexively closes as a result of this sensation . Eyebrows and eyelashes do not grow beyond a certain length (eyelashes are rarely more than 10 mm long). However, trichomegaly can cause
10496-410: The effectiveness of 5α-reductase inhibitors for hirsutism in women, reduced body and/or facial hair growth is a likely potential side effect of these drugs in men. There are far fewer studies evaluating the side effects of 5α-reductase inhibitors in women. However, due to the known role of DHT in male sexual differentiation, 5α-reductase inhibitors may cause birth defects such as ambiguous genitalia in
10624-425: The elucidation of the biological functions of DHT. 5α-Reductase inhibitors were developed and are used primarily for the treatment of BPH. The drugs are able to significantly reduce the size of the prostate gland and to alleviate symptoms of the condition. Long-term treatment with 5α-reductase inhibitors is also able to significantly reduce the overall risk of prostate cancer, although a simultaneous small increase in
10752-560: The equator, straight hair may have (initially) evolved to aid the entry of UV light into the body during the transition from dark, UV-protected skin to paler skin. Jablonski's assertions suggest that the adjective "woolly" in reference to Afro-hair is a misnomer in connoting the high heat insulation derivable from the true wool of sheep. Instead, the relatively sparse density of Afro-hair, combined with its springy coils actually results in an airy, almost sponge-like structure that in turn, Jablonski argues, more likely facilitates an increase in
10880-531: The eyebrows. This gives a natural 3D look for those who are worried about an artificial look and it lasts for two years. Micropigmentation (permanent makeup tattooing) is also available for those who want the look to be permanent. Treatments for the various forms of hair loss have limited success. Three medications have evidence to support their use in male pattern hair loss: minoxidil , finasteride , and dutasteride . They typically work better to prevent further hair loss, than to regrow lost hair. On June 13, 2022,
11008-491: The first years of life. Hair grows everywhere on the external body except for mucous membranes and glabrous skin, such as that found on the palms of the hands, soles of the feet, and lips. The body has different types of hair, including vellus hair and androgenic hair , each with its own type of cellular construction. The different construction gives the hair unique characteristics, serving specific purposes, mainly, warmth and protection. The three stages of hair growth are
11136-425: The fur, called the harderian gland . Imprints of this structure are found in the skull of the small early mammals like Morganucodon , but not in their cynodont ancestors like Thrinaxodon . The hairs of the fur in modern animals are all connected to nerves, and so the fur also serves as a transmitter for sensory input. Fur could have evolved from sensory hair (whiskers). The signals from this sensory apparatus
11264-420: The growth rate of women's hair was faster than that of men. However, more recent research has shown that the growth rate of hair in men and women does not significantly differ and that the hair of Chinese people grew more quickly than the hair of French Caucasians and West and Central Africans. The quantity of hair hovers in a certain range depending on hair colour. An average blonde person has 150,000 hairs,
11392-514: The hair follicle and packed into granules found in the fibers. Eumelanin is the dominant pigment in brown hair and black hair , while pheomelanin is dominant in red hair . Blond hair is the result of having little pigmentation in the hair strand. Gray hair occurs when melanin production decreases or stops, while poliosis is white hair (and often the skin to which the hair is attached), typically in spots that never possessed melanin at all, or ceased for natural reasons, generally genetic, in
11520-415: The hair follicle include the oil producing sebaceous gland which lubricates the hair and the arrector pili muscles, which are responsible for causing hairs to stand up. In humans with little body hair, the effect results in goose bumps . The root of the hair ends in an enlargement, the hair bulb , which is whiter in color and softer in texture than the shaft and is lodged in a follicular involution of
11648-423: The hair follicle shape determines curl pattern, the hair follicle size determines thickness. While the circumference of the hair follicle expands, so does the thickness of the hair follicle. An individual's hair volume, as a result, can be thin, normal, or thick. The consistency of hair can almost always be grouped into three categories: fine, medium, and coarse. This trait is determined by the hair follicle volume and
11776-528: The hair is artificial. Wigs vary widely in quality and cost. In the United States, the best wigs – those that look like real hair – cost up to tens of thousands of dollars. Organizations also collect individuals' donations of their own natural hair to be made into wigs for young cancer patients who have lost their hair due to chemotherapy or other cancer treatment in addition to any type of hair loss. Though not as common as
11904-520: The hair lie flat on the skin which allows heat to leave. In some mammals, such as hedgehogs and porcupines , the hairs have been modified into hard spines or quills. These are covered with thick plates of keratin and serve as protection against predators. Thick hair such as that of the lion's mane and grizzly bear's fur do offer some protection from physical damages such as bites and scratches. Displacement and vibration of hair shafts are detected by hair follicle nerve receptors and nerve receptors within
12032-436: The hairbrush after brushing or in the basin after shampooing. Styling can also reveal areas of thinning, such as a wider parting or a thinning crown. A substantially blemished face, back and limbs could point to cystic acne. The most severe form of the condition, cystic acne , arises from the same hormonal imbalances that cause hair loss and is associated with dihydrotestosterone production. The psychology of hair thinning
12160-437: The hairline and temple area. Hair typically grows back normally and treatment is not indicated. A similar situation occurs in women taking the fertility-stimulating drug clomiphene . Other causes of hair loss include: Genetic forms of localized autosomal recessive hypotrichosis include: Hair follicle growth occurs in cycles. Each cycle consists of a long growing phase ( anagen ), a short transitional phase ( catagen ) and
12288-501: The hot times of the day that required efficient thermoregulation through perspiration . The loss of heat through heat of evaporation by means of sweat glands is aided by air currents next to the skin surface, which are facilitated by the loss of body hair. Another factor in human evolution that also occurred in the prehistoric past was a preferential selection for neoteny , particularly in females. The idea that adult humans exhibit certain neotenous (juvenile) features, not evinced in
12416-463: The importance of 5α-reductase inhibitors. DHT may play a function in skeletal muscle amino acid transporter recruitment and function. Metabolites of DHT have been found to act as neurosteroids with their own AR-independent biological activity. 3α-Androstanediol is a potent positive allosteric modulator of the GABA A receptor , while 3β-androstanediol is a potent and selective agonist of
12544-438: The individual's hair. A very round shaft allows for fewer disulfide bonds to be present in the hair strand. This means the bonds present are directly in line with one another, resulting in straight hair. The flatter the hair shaft becomes, the curlier hair gets, because the shape allows more cysteines to become compacted together resulting in a bent shape that, with every additional disulfide bond, becomes curlier in form. As
12672-417: The initial substrate): This pathway is not always considered in the clinical evaluation of patients with hyperandrogenism , for instance due to rare disorders of sex development like 21α-hydroxylase deficiency . Ignoring this pathway in such instances may lead to diagnostic pitfalls and confusion, when the conventional androgen biosynthetic pathway cannot fully explain the observed consequences. As with
12800-429: The lashes to grow remarkably long and prominent (in some cases the upper lashes grow to 15 mm long). Hair has its origins in the common ancestor of mammals, the synapsids , about 300 million years ago. It is currently unknown at what stage the synapsids acquired mammalian characteristics such as body hair and mammary glands , as the fossils only rarely provide direct evidence for soft tissues. Skin impression of
12928-507: The liver. The testes and prostate gland contribute relatively little to concentrations of DHT in circulation. There are two major isoforms of 5α-reductase, SRD5A1 (type 1) and SRD5A2 (type 2), with the latter being the most biologically important isoenzyme. There is also third 5α-reductase: SRD5A3 . SRD5A2 is most highly expressed in the genitals, prostate gland , epididymides , seminal vesicles , genital skin , facial and chest hair follicles, and liver , while lower expression
13056-421: The loss of hair on the head, chemotherapy, hormone imbalance, forms of hair loss, and other factors can also cause loss of hair in the eyebrows. Loss of growth in the outer one third of the eyebrow is often associated with hypothyroidism . Artificial eyebrows are available to replace missing eyebrows or to cover patchy eyebrows. Eyebrow embroidery is another option which involves the use of a blade to add pigment to
13184-408: The male fetuses of pregnant women. As such, they are not used in women during pregnancy. MK-386 is a selective 5α-reductase type 1 inhibitor which was never marketed. Whereas 5α-reductase type 2 inhibitors achieve much higher reductions in circulating DHT production, MK-386 decreases circulating DHT levels by 20 to 30%. Conversely, it was found to decrease sebum DHT levels by 55% in men versus
13312-510: The most genetically diverse continental group on Earth, Afro-textured hair approaches ubiquity in this region. This points to a strong, long-term selective pressure that, in stark contrast to most other regions of the genomes of sub-Saharan groups, left little room for genetic variation at the determining loci. Such a pattern, again, does not seem to support human sexual aesthetics as being the sole or primary cause of this distribution. A group of studies have recently shown that genetic patterns at
13440-607: The most successful species on the planet (and which also is very vulnerable at birth) was arguably a more urgent issue (axillary hair in the underarms and groin were also retained as signs of sexual maturity). Sometime during the gradual process by which Homo erectus began a transition from furry skin to the naked skin expressed by Homo sapiens , hair texture putatively gradually changed from straight hair (the condition of most mammals, including humanity's closest cousins—chimpanzees) to Afro-textured hair or 'kinky' (i.e. tightly coiled). This argument assumes that curly hair better impedes
13568-559: The onset of symptoms. Hair loss induced by cancer chemotherapy has been reported to cause changes in self-concept and body image . Body image does not return to the previous state after regrowth of hair for a majority of patients. In such cases, patients have difficulties expressing their feelings ( alexithymia ) and may be more prone to avoiding family conflicts. Family therapy can help families to cope with these psychological problems if they arise. Although not completely understood, hair loss can have many causes: Male pattern hair loss
13696-406: The opening of the hair produce a fatty secretion that lubricates the hair. Hair growth begins inside the hair follicle . The only "living" portion of the hair is found in the follicle. The hair that is visible is the hair shaft, which exhibits no biochemical activity and is considered "dead". The base of a hair's root (the "bulb") contains the cells that produce the hair shaft. Other structures of
13824-600: The other great apes, is about a century old. Louis Bolk made a long list of such traits, and Stephen Jay Gould published a short list in Ontogeny and Phylogeny . In addition, paedomorphic characteristics in women are often acknowledged as desirable by men in developed countries. For instance, vellus hair is a juvenile characteristic. However, while men develop longer, coarser, thicker, and darker terminal hair through sexual differentiation , women do not, leaving their vellus hair visible. Jablonski asserts head hair
13952-537: The other hand, although they do still show some effectiveness. Aside from pattern hair loss, the drugs are also useful in the treatment of hirsutism and can greatly reduce facial and body hair growth in women with the condition. 5α-Reductase inhibitors are overall well tolerated and show a low incidence of adverse effects . Sexual dysfunction , including erectile dysfunction , loss of libido , and reduced ejaculate volume , may occur in 3.4 to 15.8% of men treated with finasteride or dutasteride. A small increase in
14080-423: The passage of UV light into the body relative to straight hair (thus curly or coiled hair would be particularly advantageous for light-skinned hominids living at the equator). It is substantiated by Iyengar's findings (1998) that UV light can enter into straight human hair roots (and thus into the body through the skin) via the hair shaft. Specifically, the results of that study suggest that this phenomenon resembles
14208-426: The passage of light through fiber optic tubes (which do not function as effectively when kinked or sharply curved or coiled). In this sense, when hominids (i.e. Homo erectus ) were gradually losing their straight body hair and thereby exposing the initially pale skin underneath their fur to the sun, straight hair would have been an adaptive liability. By inverse logic, later, as humans traveled farther from Africa and/or
14336-626: The predominant East Asian 'coarse' or thick, straight hair texture arose within the past ≈65,000 years, which is a time frame that covers from the earliest of the 'Out of Africa' migrations up to now. Ringworm is a fungal disease that targets hairy skin. Premature greying of hair is another condition that results in greying before the age of 20 years in Europeans, before 25 years in Asians, and before 30 years in Africans. Hair care involves
14464-468: The prostate gland. In addition, unlike testosterone, DHT is inactivated by 3α-hydroxysteroid dehydrogenase (3α-HSD) into the very weak androgen 3α-androstanediol in various tissues such as muscle , adipose , and liver among others, and in relation to this, DHT has been reported to be a very poor anabolic agent when administered exogenously as a medication. In addition to normal biological functions, DHT also plays an important causative role in
14592-567: The ranges for testosterone and DHT levels in women have been found to be 20 to 70 ng/dL and 5 to 30 ng/dL, respectively. Levels of total testosterone, free testosterone, and free DHT, but not total DHT, all measured with LC–MS/MS , are higher in women with polycystic ovary syndrome (PCOS) than in women without this condition. Circulating DHT levels in eugonadal men are about 7- to 10-fold lower than those of testosterone, and plasma levels of testosterone and DHT are highly correlated ( correlation coefficient of 0.7). In contrast to
14720-443: The ratio of circulating testosterone to DHT is greatly elevated (at about 3.5 to 5 times higher than normal). Genetic males (46,XY) with 5α-reductase type 2 deficiency are born with undervirilization including pseudohermaphroditism (ambiguous genitalia), pseudovaginal perineoscrotal hypospadias , and usually undescended testes . Their external genitalia are female-like, with micropenis (a small, clitoris -like phallus ),
14848-430: The relationship depends upon the severity of baldness, while frontal baldness is not. Thus, vertex baldness might be a marker of CHD and is more closely associated with atherosclerosis than frontal baldness. A key aspect of hair loss with age is the aging of the hair follicle. Ordinarily, hair follicle renewal is maintained by the stem cells associated with each follicle. Aging of the hair follicle appears to be primed by
14976-605: The risk of affective symptoms including depression , anxiety , and self-harm may be seen. However risk within the affected group can vary very strongly with some patients vividly reporting very strong persistent effects. Both the sexual dysfunction and affective symptoms may be due partially or fully to prevention of the synthesis of neurosteroids like allopregnanolone rather necessarily than due to inhibition of DHT production. A small risk of gynecomastia has been associated with 5α-reductase inhibitors (1.2–3.5%). Based on reports of 5α-reductase type 2 deficiency in males and
15104-452: The risk of certain high-grade tumors has been observed. In addition to prostate diseases, 5α-reductase inhibitors have subsequently been developed and introduced for the treatment of pattern hair loss in men. They are able to prevent further progression of hair loss in most men with the condition and to produce some recovery of hair in about two-thirds of men. 5α-Reductase inhibitors seem to be less effective for pattern hair loss in women on
15232-602: The skin. Hairs can sense movements of air as well as touch by physical objects and they provide sensory awareness of the presence of ectoparasites . Some hairs, such as eyelashes , are especially sensitive to the presence of potentially harmful matter. The eyebrows provide moderate protection to the eyes from dirt , sweat and rain . They also play a key role in non-verbal communication by displaying emotions such as sadness, anger, surprise and excitement. In many other mammals, they contain much longer, whisker-like hairs that act as tactile sensors. The eyelash grows at
15360-463: The temples and the crown and hair either thins out or falls out. Female-pattern hair loss occurs at the frontal and parietal . People have between 100,000 and 150,000 hairs on their head. The number of strands normally lost in a day varies but on average is 100. In order to maintain a normal volume, hair must be replaced at the same rate at which it is lost. The first signs of hair thinning that people will often notice are more hairs than usual left in
15488-405: The time the subject is 25 years old. Symptoms of hair loss include hair loss in patches usually in circular patterns, dandruff, skin lesions, and scarring. Alopecia areata (mild – medium level) usually shows in unusual hair loss areas, e.g., eyebrows, backside of the head or above the ears, areas the male pattern baldness usually does not affect. In male-pattern hair loss, loss and thinning begin at
15616-410: Was evolutionarily advantageous for pre-humans to retain because it protected the scalp as they walked upright in the intense African (equatorial) UV light . While some might argue that, by this logic, humans should also express hairy shoulders because these body parts would putatively be exposed to similar conditions, the protection of the head, the seat of the brain that enabled humanity to become one of
15744-430: Was needed. Environmental factors are under review. A 2007 study indicated that smoking may be a factor associated with age-related hair loss among Asian men. The study controlled for age and family history, and found statistically significant positive associations between moderate or severe male pattern hair loss and smoking status. Vertex baldness is associated with an increased risk of coronary heart disease (CHD) and
15872-412: Was not realized until the early 1960s, when it was found to be produced by 5α-reductase from circulating testosterone in target tissues like the prostate gland and seminal vesicles and was found to be more potent than testosterone in bioassays. The biological functions of DHT in humans became much more clearly defined upon the discovery and characterization of 5α-reductase type 2 deficiency in 1974. DHT
16000-604: Was once known to be capable of falsifying drug tests. DHT, also known as 5α-androstan-17β-ol-3-one, is a naturally occurring androstane steroid with a ketone group at the C3 position and a hydroxyl group at the C17β position. It is the derivative of testosterone in which the double bond between the C4 and C5 positions has been reduced or hydrogenated . DHT was first synthesized by Adolf Butenandt and his colleagues in 1935. It
16128-422: Was prepared via hydrogenation of testosterone, which had been discovered earlier that year. DHT was introduced for medical use as an AAS in 1953, and was noted to be more potent than testosterone but with reduced androgenicity. It was not elucidated to be an endogenous substance until 1956, when it was shown to be formed from testosterone in rat liver homogenates. In addition, the biological importance of DHT
16256-475: Was the last major sex hormone, the others being testosterone, estradiol , and progesterone , to be discovered, and is unique in that it is the only major sex hormone that functions principally as an intracrine and paracrine hormone rather than as an endocrine hormone. DHT was one of the original "underground" methods used to falsify drug testing in sport, as DHT does not alter the ratio of testosterone to epistestosterone in an athlete's urinary steroid profile,
16384-432: Was traditionally used as a treatment for hair loss. Research is looking into connections between hair loss and other health issues. While there has been speculation about a connection between early-onset male pattern hair loss and heart disease, a review of articles from 1954 to 1999 found no conclusive connection between baldness and coronary artery disease. The dermatologists who conducted the review suggested further study
#49950