paeds9

A 16-year-old girl presents to the clinic with a 4-month history of no menstrual bleeding. Menarche was at 11 years of age. She denies experiencing any headache or visual disturbances. Physical examination shows an overweight girl, with facial hair, acne vulgaris on the face and a deep voice. Abdominal examination shows no abnormalities and a pregnancy test is negative. Diagnosis can be confirmed with which of the following lab test?