UKMLA PLAB AMC USMLE Prometric MCQ

Answer: B

Elevated LH/FSH ratio
Polycystic ovarian syndrome is one of the commonest causes of anovulatory infertility. Patients can have a normal menstrual cycle but are more likely to have oligomenorrhoea. It is associated with a number of biochemical abnormalities, including raised LH levels, normal or elevated testosterone but with a low SHBG (sex-hormone-binding globulin) resulting in a high free-androgen index. Androstenedione levels can either be normal or raised. The underlying biochemical defect in patients with PCOS is recognised to be insulin resistance. This causes high circulating insulin levels due to peripheral insulin resistance: therefore hyperinsulinaemia, and not low insulin levels, is characteristic of the condition. The insulin resistance has been shown in both lean and obese patients with the condition.