Differential Diagnosis of Hyperandrogenism in Women with Polycystic Ovary Syndrome

According to the Androgen Excess and Polycystic Ovary Syndrome Society (AE&PCOS), the main feature of PCOS is clinical hyperandrogenism or laboratory hyperandrogenaemia. Therefore, in diagnosing PCOS one must always exclude other causes of androgen excess. In a woman with hyperandrogenism, the diagnosis of PCOS can usually be made according to the patient's history and careful clinical examination. Signs of mild hyperandrogenaemia usually start after the menarche and cycles continue to be anovulatory in adult life. Non-classical congenital adrenal hyperplasia (NCCAH) can be another cause of hyperandrogenism with oligomenorrhea. This can be diagnosed ill a patient with elevated basal or ACTH stimulated serum 17OH-progesterone (17-OHP) levels or in a case of a significant decrease in serum testosterone (TST) and dehydroepiandrosterone sulphate (DHEA-S) in a two day dexamethasone suppression test. Cushing's disease (ACTH producing pituitary adenoma) is a rare cause of hyperandrogenaemia in women with recent onset of hyperandrogenism. However, it must always be taken into the consideration in a patient with accompanying signs of hypercortisolism. It can usually be excluded by performing an overnight dexamethasone suppression test or the measurement of 24 h urinary free cortisol levels. Severe signs of hyperandrogenism which lead to virilization should always lead to the exclusion of androgen secreting tumors of ovarian or adrenal origin. These are very rare but should be always taken into the account in a patient with recent onset of severe signs of androgen excess and very high serum androgen levels. Mild signs of hyperandrogenaemia in a woman with recent oligomenorrhea should always lead to the exclusion of hyperprolactinaemia.