The polycystic ovary syndrome (PCOS) is the commonest endocrinological disorder in women of reproductive age (prevalence of about 8-10%). The definition of this syndrome is now much wider than that originally ascribed to the classical Stein- Leventhal syndrome as "a clinical entity in terms of history of oligomenorrhoea, hirsutism, obesity and enlarged sclerocystic ovaries". The many features of the syndrome can be broadly divided into three categories: clinical, biochemical and metabolic. The clinical features include abnormalities of the menstrual cycle (irregular or absent periods), hirsutism (unwanted hair growth) , acne, androgenic alopecia (hair loss at the crown of the scalp), anovulatory infertility and recurrent miscarriages. The characteristic biochemical features are elevated LH, generally accompanied by raised testosterone and/or androstenedione levels and decreased sex hormone binding globulin (SHBG). The metabolic disturbances of this syndrome include insulin resistance, obesity, lipid abnormalities and an increased risk for impaired glucose tolerance and type 2 diabetes mellitus.
Although women with PCOS are often amenorrhoeic (absent periods), infertile and hirsute, they do not necessarily have each feature of the triad. In fact PCOS is a heterogeneous disorder and, therefore, a lack of clinical uniformity is frequent. Two of the following are required for the diagnosis of PCOS, according to the Rotterdam 2003 PCOS consensus workshop: a) oligo or amenorrhoea, b) clinical or biochemical signs of hyperandrogenaemia, c) polycystic appearance of ovaries on ultrasound (as defined by more than 12 cysts with a diameter of 2-9 mm).
Oral contraceptives, progestogens, antiandorgens and ovulation induction agents are regarded as standard therapy for PCOS. The most significant advance in the understanding of PCOS has been the recognition that insulin resistance is a key component in the pathogenesis of the syndrome. This provided the basis for recent developments in treatment strategies for women with PCOS, using insulin sensitizing agents. Among them, metformin has been shown to be useful alone or in combination with standard therapy.