What is the most appropriate initial diagnostic study for a woman with signs of polycystic ovarian syndrome?

The most appropriate initial diagnostic study for a woman with signs of polycystic ovarian syndrome (PCOS) is measuring free testosterone levels. PCOS is characterized by a combination of symptoms including irregular menstrual cycles, signs of hyperandrogenism (such as hirsutism or acne), and polycystic ovaries observed on ultrasound.

Hyperandrogenism plays a significant role in the pathophysiology of PCOS. Elevated levels of androgens, such as testosterone, are common in women with this condition. Free testosterone specifically is often measured because it represents the biologically active form of the hormone, which is responsible for the clinical signs associated with hyperandrogenism.

By identifying abnormal testosterone levels, clinicians can confirm the presence of hyperandrogenism, which is one of the key diagnostic criteria for PCOS. This measurement ultimately helps guide further evaluation and management, including lifestyle modifications and potential pharmacological therapies.

Other diagnostic tests like prolactin levels, endometrial biopsy, and thyroid-stimulating hormone (TSH) are valuable in different clinical contexts but are not specific for diagnosing PCOS. Measuring prolactin can help rule out prolactinomas, an unrelated condition that can also cause menstrual irregularities