Female Androgenetic Alopecia: An Update on Diagnosis and Management

Michela Starace; Gloria Orlando; Aurora Alessandrini; Bianca Maria Piraccini

Disclosures

Am J Clin Dermatol. 2020;21(1):69-84. 

In This Article

Diagnosis

Medical History

Age of onset, duration and progression of the hair loss should be investigated. In many cases, the family history has a positive response, if it is negative, FAGA can't be excluded.

Patients should be asked about thinning and shedding. Usually they describe a hair thinning on the central scalp and complain about an increased visibility of the scalp through the hair in this area. Patients should be investigated for menarche, menstrual irregularities, menopause, amenorrhea, difficult in conceiving, signs of virilization (hirsutism, deepening voice, clitoral enlargement) and acne. Closer attention must be observed to drugs that can induce hyperandrogenism such as anabolic-androgenic steroids, synthetic proandrogens, progestins and antiepileptics. Other causes of hair loss should be excluded such as iron deficiencies, thyroid dysfunctions, medical treatment, infections, deficient diet and rapid weight loss.

Physical Examination

It is useful to perform a complete clinical examination in order to find other signs of hyperandrogenism, such as acne and hirsutism. Hirsutism should be evaluated in locations where typically women do not develop terminal hair (face, abdomen, back and chest) and estimated with the Ferryman-Gallwey scale (Figure 4). In Caucasian woman, a score of 8 or higher is indicative of hirsutism.

Figure 4.

Clinical presentation of hirsutism on the face and the abdomen of a woman affected by female androgenetic alopecia (FAGA)

Impaired fertility, menstrual irregularities, amenorrhea, hypertrichosis, hyperseborrhoea, obesity and severe acne may be indicative of PCOS.[1]

Scalp Examination

The diagnosis of FAGA is usually made clinically. A scalp biopsy should be recommended for cases of uncertain diagnosis but also for very young patients, patients with diffuse FAGA and those who have suspicious clinical features for the cicatricial forms. Since the occipital scalp is not under androgen control and not involved in FAGA, the best way to evaluate the hair thinning is by parting hair vertically, both in the central and occipital scalp, and comparing these two areas.[25]

Several scales have been developed in order to evaluate the severity of FAGA. Ludwig's scale is divided into three degrees, from a mild light thinning in the first degree, to a complete absence of hair in the central scalp in the third degree.[31] Savin's scale quantifies eight stages of increasing crown balding, and in addition there is a special subcategory to detect frontal anterior recession.[31] Sinclair's classification includes five colour photographs of women's scalps with the hair parted centrally; it is a photographic measure of patients' perception of the severity of their hair loss.[31] Olsen's classification is similar to Ludwig's classification, but it underscores the accentuation of fronto-vertical alopecia, with a triangular or 'Christmas tree' pattern.[31]

Pull Test. Pull test could be positive in the central scalp and in the initial phases of FAGA, showing telogen roots. It is usually negative in long-standing forms and the hair shedding does not involve the scalp diffusely.

Trichoscopy. Trichoscopy is a non-invasive technique based on dermoscopic evaluation of the scalp, which allows a 10× magnification. Recently, besides manual trichoscopy, videodermoscopy has gained importance. It is a non-invasive diagnostic tool, initially used to evaluate and monitor pigmented skin lesions, that has proven to be useful in the scalp diseases. A magnification ranging from 20× to 70× allows the in vivo visualization of scalp epidermis, follicles, hair shafts and vascular patterns. Moreover, images can be stored to get a global photographic assessment that can be used in further controls to evaluate the hair growth.[32]

The main trichoscopical sign in FAGA is the presence of hair diameter variability > 20%.[33] Moreover, it may show yellow dots that are indicative of empty follicles, small areas of focal atrichia and peripilar hyperpigmentation.[34,35] Follicular ostia are usually preserved, helping in the differential diagnosis of scarring alopecia (Figure 5).

Figure 5.

Trichoscopy of female androgenetic alopecia (FAGA): reduced hair thickness with hair diameter variability, reduced number of hairs with empty follicle (×20 magnification)

In 2009, Rakowska et al.[36] proposed major and minor dermoscopic criteria for the diagnosis of FAGA. Major criteria include (1) more than four yellow dots in four images in the frontal area; (2) lower average hair thickness in the frontal area compared with the occipital area and (3) >10% of thin hairs (< 0.03 mm) in the frontal area. Minor criteria include (1) increased frontal to occipital ratio of single-hair pilosebaceous units; (2) vellus hairs and (3) perifollicular discoloration. The diagnosis of FAGA is made with the presence of two major criteria or one major plus two minor criteria.

Biopsy. It can be useful when the clinical evaluation does not provide a definitive diagnosis, and cicatricial alopecias or alopecia areata are suspected. From our experience, we recommend the dermoscopy-guided biopsy of the scalp technique with a 4-mm punch involving the dermis. Dermoscopy helps select the most significant site to perform the biopsy, leading to a definitive pathological diagnosis in almost all cases. In early stages of FAPD, for instance, dermoscopy identifies even small areas of cicatricial alopecia and therefore it allows a correct clinical-pathological diagnosis promptly. It is best to avoid the bitemporal area as this region may have miniaturized hairs in women without hair loss. Vertical and horizontal sectioning should be evaluated.[7,37] Horizontal sections enable the evaluation of the number of hairs per field of view. In FAGA, there is an increased number of miniaturized (vellus-like) hairs (Figure 6). The ratio of terminal to vellus-like hair follicles is typically < 3:1 in women with this condition against > 7:1 in the normal scalp.[38] Other typical histopathological features are an increase of telogen/anagen ratio and an increased number of follicular stelae.[7] Low levels of mild perifollicular inflammation around the upper portion of the hair follicle as well as perifollicular fibrosis may be present.

Figure 6.

Histopathology of female androgenetic alopecia (FAGA) with increased number of miniaturized (vellus-like) hairs

Biochemical Examinations. A hyperandrogenic state should be considered in women with FAGA associated with signs of androgen excess (e.g. hirsutism, irregular menses, acne, hyperprolactinemia, acanthosis nigricans); while it is not indicated in all women with FAGA.[1] Free androgen index test (FAI = total testosterone [nmol L−1] × 100/sex hormone binding globulin [SHBG]) and prolactin as screening parameters for ovarian hyperandrogenism and dehydroepiandrosterone sulfate (DHEA) and 17-hydroxyprogesterone (17-OH-P) as screening parameters for androgen-producing tumours and adrenal congenital hyperplasia are recommended.[39] Note that testing of androgen levels should be done during the follicular phase, between the fourth and the seventh day of the cycle, and that oral contraceptives should be discontinued for at least 2 months prior to this testing.[40]

Ovarian and adrenal ultrasound could be prescribed to rule out the presence of ovarian cysts and androgen-producing tumours or adrenal congenital hyperplasia.[39] Depending on the results, further investigations may be needed and an interdisciplinary approach involving gynaecologists, endocrinologists and dermatologists may be required.[39]

Measurements of blood iron, ferritin, vitamin D, zinc and thyroid profile may be useful to assess and treat other conditions that may impact on hair regrowth in FAGA.[1]

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