REVIEW Nina L. Tamashunas, BS Wilma F. Bergfeld, MD, FAAD Department of Dermatology, Cleveland Clinic, Cleveland, Senior Dermatologist, and Director, Dermatopathology OH; Case Western Reserve University School of Medicine, Fellowship, Departments of Dermatology and Pathology, Cleveland, OH Cleveland Clinic, Cleveland, OH; Past President, American Academy of Dermatology, American Society of Dermato- pathology, and the American Dermatologic Association Male and female pattern hair loss: Treatable and worth treating ABSTRACT attern hair loss is a progressive, non- P scarring form of hair loss characterized Pattern hair loss is the most common type of hair loss in by gradual loss of terminal hair and follicular both men and women. Scalp hair is typically affected in a miniaturization to vellus hair fi bers on the characteristic distribution without other scalp or derma- scalp in a characteristic distribution. It is the tologic fi ndings. Early recognition and treatment can help most common form of hair loss in both men halt its progression to preserve as much hair as possible. and women and has psychosocial effects, in- Both pharmacologic and nonpharmacologic treatments cluding stress and diminished quality of life. have proven helpful. This review focuses on clinical presentation, diagnosis, and treatment of pattern hair loss. KEY POINTS Male and female pattern hair loss is a nonscarring, pro- ■ MANY NAMES FOR IT gressive form of alopecia that typically affects the tempo- This condition goes by many names, such as ral, frontal, and vertex scalp in men and central scalp in androgenetic alopecia, androgenic alopecia, women. male balding, male pattern hair loss, female pattern alopecia, diffuse alopecia in women, The process can begin soon after puberty, and the result- and hereditary alopecia. The term “androge- ing hair loss negatively affects quality of life and self- netic alopecia” was used in the past, recogniz- image. ing the hormonal and hereditary infl uences underlying the condition in men. As our understanding of both the patho- Pattern hair loss is commonly diagnosed with a thorough physiology and phenotypic expression expand- history; physical examination of the face, scalp, and nails; ed, so did the collection of terms used to iden- the hair-pull test; dermoscopy; and laboratory testing. tify this disorder. Newer terminology developed A hair biopsy may be of value for clinically challenging to express the different patterns of presentation cases. in men and women and the uncertain role, and frequent absence, of androgen excess in wom- Topical minoxidil and oral fi nasteride are fi rst-line treat- en. Male pattern hair loss and female pattern hair ments for male pattern hair loss and topical minoxidil loss are now the favored terms. is the fi rst-line therapy for female pattern hair loss, but ■ there are a number of other off-label pharmacologic and GENES PLAY A ROLE nonpharmacologic treatments. Male and female pattern hair loss are poly- genic conditions, which explains their high prevalence and variable phenotypic expres- sion.1 Epigenetic modifi cations may alter ge- netic susceptibility.1 Interestingly, genetic variations associated doi:10.3949/ccjm.88a.20014 with the androgen receptor gene (AR) have CLEVELAND CLINIC JOURNAL OF MEDICINE VOLUME 88 • NUMBER 3 MARCH 2021 173 Downloaded from www.ccjm.org on September 28, 2021. For personal use only. All other uses require permission. HAIR LOSS ■ LINKED TO ANDROGEN EXCESS IN MEN Androgens are considered necessary for male pattern hair loss to develop. The condition typically begins after the start of puberty, which is marked by a striking increase in an- drogen levels. Dihydroxytestosterone, a po- tent metabolite of testosterone synthesized in a reaction catalyzed by 5-alpha reductase in the peripheral target organs, hair follicle, and sebaceous glands, plays a role in normal hair growth and male pattern hair loss develop- ment in androgen-sensitive areas such as the vertex and frontal scalp, beard, axilla, pubis, and extremities. Dihydroxytestosterone assists normal hair growth in these areas, but elevated cellular levels of androgen receptors and 5-al- pha reductase3 and increased production of di- hydroxytestosterone4 have been documented in cases of male pattern hair loss. No cases of male pattern hair loss have been documented in men with 5-alpha reductase defi ciencies.5 ■ UNCLEAR RELATIONSHIP WITH HORMONES IN WOMEN The relationship between androgens and fe- male pattern hair loss is less clear. Female pat- tern hair loss has been observed in women with high androgen levels,6 but it has also been documented in a patient with complete androgen insensitivity syndrome.7 Addition- ally, most women with female pattern hair loss have normal testosterone levels and lack clin- Figure 1. Male pattern hair loss. ical manifestations of hyperandrogenemia.6 The role of circulating estrogens in the de- been linked to development of male pattern velopment of female pattern hair loss is also hair loss, but genes for aromatase (CYP19A1), unclear. The prevalence of hair loss increases estrogen receptor-a (ESR1), type I 5-alpha re- after menopause. Evidence is confl icting re- ductase (SRD5A1), and insulin-like growth garding whether estrogen stimulates or inhib- factor 2 (IGF-2) do not have any established its the hair follicle.1 association with it.1 ■ Research into genetic associations with fe- CAN BEGIN EARLY male pattern hair loss is less extensive and ro- Pattern hair loss in men and women begins bust than that of male pattern hair loss. Study- soon after puberty. Thinning of hair and non- ing the relationship between female pattern hair scarring loss of terminal hairs, resulting in a loss and AR has proven diffi cult, since AR is lo- decrease in hair density, generally progress slowly over years. The scalp is healthy without cated on the X chromosome, which undergoes 1 associated symptoms. X inactivation in women. An allelic variant of In men, hair loss typically affects the cen- CYP19A1 was associated with a predisposition tral scalp, including the midfrontal, temporal, to female pattern hair loss in a genome-wide as- and vertex regions (Figure 1). The 7-stage sociation study.2 Hamilton-Norwood scale is commonly used 174 CLEVELAND CLINIC JOURNAL OF MEDICINE VOLUME 88 • NUMBER 3 MARCH 2021 Downloaded from www.ccjm.org on September 28, 2021. For personal use only. All other uses require permission. TAMASHUNAS AND BERGFELD to classify male pattern hair loss.8 However, in some men, hair loss does not follow this typi- cal progression or is more severe in particular areas. In women, the characteristic distribution of hair loss is different. Female pattern hair loss has 2 general distributions: diffuse thinning across the central scalp and the characteristic “Christmas tree” pattern observed along the midline part of the hair due to prominent hair thinning towards the front of the scalp with minimal involvement of the hairline (Figure 2).9,10 The frontal hairline is less likely to be involved, but bitemporal thinning is com- mon. The 3-grade Ludwig scale is commonly used to characterize female pattern hair loss.11 Figure 2. Female pattern hair loss. ■ A CLINICAL DIAGNOSIS a sheet of paper as a backdrop and comparing Pattern hair loss is typically diagnosed clini- the caliber of adjacent hair shafts. cally (Table 1). Infl ammation, scarring, or scaling of the History scalp suggests a different diagnosis, as pattern hair loss is usually unaccompanied by these A thorough history should be elicted, includ- ing age of onset of hair loss, time course, se- signs. Nevertheless, seborrheic dermatitis is more prevalent in people with pattern hair verity, hair loss distribution, progression (ie, 12 periods of shedding), and accompanying loss, so male and female pattern hair loss can symptoms. For women, a gynecologic history present with another scalp condition. Sebor- may help uncover an underlying cause such rheic dermatitis is often associated with sebor- Male pattern as polycystic ovarian syndrome or hyperan- rhea (oily scalp) which is a result of androgen and female stimulation of the sebaceous glands. drogenism. The patient should be asked about pattern any family history of hair loss, metabolic syn- Nail involvement (eg, pitting, trachy- dromes (eg, diabetes mellitus), and androgen onychia, and longitudinal ridging) and patchy hair loss hair loss in nonscalp regions (eg, the eye- excess; medications; and medical history. are polygenic Conditions that worsen hair loss, includ- brows) are inconsistent with the diagnosis of ing iron defi ciency, thyroid dysfunction, and male or female pattern hair loss. conditions nutritional defi ciencies, should be considered Hair-pull test and managed to improve treatment results. The hair-pull test, which is useful in detecting Physical examination active hair loss, is performed by grasping 50 to A complete skin evaluation should be con- 60 hairs close to the scalp with the thumb, in- ducted, including the face, scalp, and nails. dex, and middle fi ngers and slowly pulling. If 6 or When examining the scalp, note the dis- more hairs come loose, hair loss is likely active. tribution of hair loss, the caliber of hairs, and Extracted hair can be examined under other clinical features. Male pattern hair loss the microscope to characterize the type (eg, typically presents as a receding hairline and broken or dystrophic) and the phase (eg, telo- hair miniaturization on the frontal and ver- gen [resting] or anagen [growth]). A study by tex scalp. In women, the vertex and midfron- McDonald et al13 suggested that neither wash- tal scalp are commonly affected, as described ing nor brushing the hair affects results of the above. Hair loss can be assessed by comparing hair-pull test. In pattern hair loss, the hair- the hair part of the central scalp with that of pull test is generally negative, though it can the occipital scalp, which is generally spared. be positive early in the process on the vertex Hair miniaturization can be seen better using or midfrontal scalp.