Advanced laboratory services

CAUSES OF HIRSUTISM 

Hirsutism is defined as the excessive growth of terminal hair on the face and body of a female in a typical male pattern distribution. The causes of hirsutism are summarised in Table. Polycystic ovary syndrome This is by far the most common cause of hirsutism. Diagnosis rests on the finding of polycystic ovaries on pelvic ultrasound. In polycystic ovary syndrome (PCOS), the ovary, rather than the adrenal gland, is the principal source of androgen excess, hence these women usually benefit from therapy targeted at ovarian and/or pituitary FSH and LH suppression.

Idiopathic hirsutism

This is defined as hirsutism in women with regular cycles, normal ovaries on ultrasound and no other pathology to account for their symptoms. It was believed to be the most common cause of hirsutism until the true prevalence of PCOS in hirsute women was appreciated and probably only accounts for 6% of cases.

Late-onset congenital adrenal hyperplasia

This pathology can be easily missed as 83% of affected women also have polycystic ovaries on ultrasound secondary to the hyperandrogenaemia. Late-onset CAH should always be considered in women with polycystic ovaries on scanning but serum testosterone levels of over 200 ng/dL. 

Androgen-secreting tumours of the ovary or adrenal

These are very rare but must be excluded in any woman who develops hirsutism or virilisation over a short time period and/or has a serum testosterone level above 200 ng/dL.

DIAGNOSIS
After thorough history and clinical examination, initial laboratory tests to exclude a serious underlying disease include: 

·  Serum testosterone and

·  DHEAS, 

because the measurement of these 2 hormone levels can detect most androgen-producing tumors. A serum testosterone level >200 ng/dL is highly suggestive of an adrenal or ovarian tumor. If serum testosterone is elevated despite a normal DHEAS level, an ovarian source is more likely. If a DHEAS level >700 μg/dL is present despite a normal serum testosterone level, an adrenal source should be suspected as the cause of hirsutism. When an adrenal or ovarian neoplasm is suspected, diagnostic imaging to confirm the location of the neoplasm is helpful in guiding treatment. Mildly elevated serum testosterone and DHEAS are often present in PCOS and late-onset CAH. A second stage of diagnostic testing can help differentiate these functional sources of hirsutism. 

·  An elevated 17-hydroxyprogesterone (5000–10,000 ng/dL [50–300 nmol/L]) is seen in women with late onset CAH.  Evaluation should begin by obtaining an unstimulated serum 17-hydroxyprogesterone in the morning during the follicular stage of the menstrual cycle.

·  Patients with PCOS generally have increased free testosterone (>50 ng/dL), with elevated luteinizing hormone (LH) and decreased follicle-stimulating hormone (FSH) (FSH:LH = 1:2 or 1:3). 

·  In the presence of both amenorrhea and hirsutism, prolactin levels and thyroid function tests should be obtained to differentiate hyperprolactinemia and hypothyroidism.

Source: D. Nikolaoua, C. Gilling-Smith: Hirsutism; Current Obstetrics & Gynaecology (2005) 15, 174–182