Aetiology of FPHL:
Deleted: One of the mechanisms of FPHL is considered to be due to androgenic factors.In women testosterone formation occurs mainly in the skin. Dehydroepiandrosterone (DHEA), DHEA sulphate and androstenedione are secreted via the adrenals and ovaries and then peripherally converted to testosterone (16). Testosterone needs to be converted to dihydrotestosterone by 5α reductase (Type 1 and 2) expressed in various tissues such as sex organs and skin in order to be biologically active on the pilosebaceous unit and initiate hair loss. Furthermore recent studies also have found an association between FPHL and lack of p450 α aromatase enzyme, an enzyme that catalyses conversion of testosterone to oestradiol thereby reducing the amount of intrafollicular testosterone available for conversion to dihydrotestosterone (DHT) (17).However these are not the only causes of hair loss and it can even occur in women with normal circulatory androgens. In fact most women with FPHL show no clinical or biochemical evidence of androgen excess (18). This is where the role of genetic and family history becomes important and in fact due to lack of the clear role of androgens, the term FPHL is preferred to androgenetic hair loss (15, 19). Finally sometimes even the history and family history fails to explain the cause of hair loss and that makes FPHL even more confusing (18).
Deleted: History: As discussed before, a proper history is the key for the right diagnosis. Family history of hair loss (male and female), previous illnesses, surgeries, pregnancy and exposure to medications should be elucidated.
Deleted: Physical examination of the hair is still an important part of making the right diagnosis, although recently, dermatoscopy, digital hair microscopy and scalp biopsy have extensively replaced physical testing. Some of the useful exams are summarised here(9):
Deleted: Pull test or traction test or “Sabouraud’s sign”: normally after a gentle pull not more than five hair can be retrieved, while in hair loss this number increases (20, 21).
Deleted: Tug test: in this test a group of 50 to 70 hairs are pulled using a haemostat and then examined under the microscope. This technique has mainly been replaced with skin biopsy as it is a quite painful examination.
Deleted: Slide technique: holding hair with two fingers and then rubbing it toward the scalp with other thumb and index finger of other hand. If it resists the movement and loses its’ shape, it is a sign of cuticle damage.
Deleted: Roll technique: rolling few hair shafts between thumb and index finger can give some idea about the hair shaft diameter and the progression of terminal hair toward vellus hair.
Deleted: Hair count: the patient is asked to keep the count of their daily hair loss and collect the hair lost in one day and bring to the practice for examination under the microscope. Because of its difficulty, the hair wash method has been suggested instead, where the patient collects their hair after each shower for five days and brings them to their doctor (22).
Deleted: Density mapping: by scoring the hair density from 0 to 10 in a pictorial manner one can clarify the pattern of hair loss.
Deleted: All previous examinations can still be very useful but have been mostly replaced by dermatoscopic examination or scalp biopsy. In dermatoscopic examination some of the commonly signs during examination are – seeing hair shafts with different diameters, brown halo spots at the follicular ostium around the hair shaft, empty follicles and finally scalp pigmentation due to sun damage (23).
Deleted: For performing scalp biopsy it is recommended to take three, 4 mm core biopsies in the direction of the hair follicles from the central scalp to rule out chronic telogen effluvium, diffuse alopecia areata or cicatricial hair loss (mainly in African women) and differentiate it from FPHL. In normal scalp the ratio of terminal to vellus or vellus like hair is usually 7:1 In FPHL it is 2.2-4:1 and it is more than 8:1 in chronic telogen effluvium. 5-6:1 is considered indeterminate. The total number of hairs/cm2 in FPHL is usually significantly less than the normal 240-400 /cm2. It may be as low as 30-50 hairs/cm2(8, 18).
Deleted: Laboratory tests: Full blood count (FBC), TSH, Iron studies, serum zinc, ANA and Rheumatoid factor are a good start(24, 25). Most women with FPHL don’t have any signs of hyperandrogenism and androgenic tests might not be necessary. Patients who have hirsuitism or are overweight, those with moderate to severe acne, or acne that is resistant to treatment, patients with acanthosis nigricans ,women with irregular periods or presence of galactorrhea are good candidates for androgen studies. For these patients, free testosterone, DHEA sulphate and Sex Hormone Binding Globulin (SHBG), 5α Dihydrotestosterone, FSH, LH, Progesterone and Oestrogen levels (preferably at day 1-14 of cycle) should be tested while patients are off hormonal contraceptives for a month. Prostate specific antigen (PSA) also has been considered as a marker of androgenisation (0.02 ng/ml in premenopausal and 0.04 in postmenopausal women) (26).Testosterone or DHEA sulphate more than twice as the normal range should be referred to an endocrinologist to rule out malignancies. A Prolactin level should be requested if there are suspicions of galactorrhea(18)