<prompt> A 28-year-old lady has put on weight 10 kg over a period of 3 years and has oligomenorrhoea followed by amenorrhoea for 8 months. The blood pressure is 160100 mm of Hg. Which of the following is the most appropriate investigation?Serum electrolytesPlasma coisolPlasma testosterone and ultrasoundT3, T4 and TSH  <response>: Weight gain Oligomenorrhea ---Cushing syndrome. Coisol inhibits gonadotropin release that explains the amenorrhea. Hypeension in these patients is secondary to increased coisol that has some mineralocoicoid activity also. Excess glucocoicoids also interfere with central regulatory systems, leading to suppression of gonadotropins with subsequent hypogonadism and amenorrhea, and suppression of the hypothalamic pituitary-thyroid axis, resulting in decreased TSH thyroid-stimulating hormone secretion. Weight gain menorrhagia isolated diastolic hypeension in the question would have prompted thyroid dysfunction as the first answer. 