Polycystic Ovarian Syndrome, or PCOS, is a remarkably common condition, affecting around 5 - 10% of women of reproductive age. It is the source of much unhappiness; not only does it affect a woman's appearance (causing acne, facial hair and weight gain) but also her traditional function in society - her role as mother (women with PCOS have fertility problems).

Fortunately PCOS can be treated, though generally with varying degrees of success. Fertility can in many cases be substantially improved, and the symptoms (for example irregular periods and pelvic pain) and signs (such as acne and male pattern hair distribution) can be controlled.

But in order to treat any condition, we need first to be able to reliably diagnose it, and that is one of the main problems surrounding PCOS at the moment. The reason for this is that PCOS is a heterogeneous condition - which means that it has many different manifestations, which aren't always present in all women with PCOS. For example, polycystic ovaries (which give the condition its name) are only present in about 80% of women with PCOS. Furthermore, having polycystic ovaries does not mean that you have PCOS. Around 50% of women with polycystic ovaries have PCOS. The rest are either due to normal variations, or other conditions which cause multiple ovarian cysts.

The three main features of the syndrome include the clinical symptoms and signs (such as menstrual abnormalities, hirsutism, acne, anovulatory infertility and recurrent miscarriages), hormonal abnormalities (especially increased androgens and LH), and metabolic problems (such as insulin resistance and its associated conditions). However, not all of these are always present in women with PCOS, and those that are present, like insulin resistance, cannot be reliably detected using simple, practical tests.

Because of this variability there remains no single diagnostic test which can be used to diagnose PCOS. Instead, a combination of factors is used... evidence of hyperandrogenism (too many male hormones in the blood) and anovulation (failure of the ovary to release egg cells on a cyclical basis), in the absence of any other conditions which can cause the above problems.

It sounds complicated. But PCOS is complicated, and because of this, it should always be diagnosed and managed by a qualified healthcare practitioner. One day we should be able to diagnose it with certainty (once the genetic code for PCOS is mapped out) but until then it remains an educated guess!

Dr Guin Van Niekerk is the author of "Why Fat Sticks : An Introduction to Insulin Resistance" For more information go to www.insulinresistancesite.com