What causes Polycystic Ovarian Syndrome (PCOS)?

The cause of PCOS is not known. It is currently believed that there is a complex interplay between genetic and hormonal factors. This has resulted in five different variants of the syndrome:

1. Traditional PCOS - Oligomenorrhoea/ amennorhoea, increased androgens, no insulin resistance
2. Non-traditional PCOS -, normal androgens, obese, insulin resistant or type 2 diabetes
3. Non-traditional PCOS -- Ovulatory, increased androgens, mild insulin resistance
4. Endocrine syndrome X - Oligomenorrhoea/ amennorhoea, increased androgens, insulin resistance or type 2 diabetes
5. Idiopathic hirsutism -- ovulatory, increased androgens, no insulin resistance