A 25-year-old lady has put on weight and has oligomenorrhea followed by amenorrhea for 8 months. The blood pressure is 160/100 mm of Hg. Which of the following is the most appropriate investigation?

Ans. B. Plasma cortisolThe given clinical situation suggests a diagnosis of Cushing's which is diagnosed by Cortisol levels.* Weight gain with oligomenorrhea points to Cushing's syndrome.* Cortisol inhibits gonadotropin release that explains amenorrhea.* Hypertension in these patients is secondary to increased cortisol that has some mineralocorticoid activity also.