<prompt> A middle aged female presents with increasing visual loss, breast enlargement and irregular menses. Investigation of choice would be:S. calcitoninS. prolactinS. hemoglobin concentrationS. calcium  <response>: A middle aged female is presenting with:Increasing visual lossBreast enlargementIrregular mensesAll these features can be explained by pituitary adenoma.Most common type of pituitary adenomas prolactinomasProlactinomas can be diagnosed by raised serum prolactin levels so, the investigation of choice here is serum prolactin levelAlso Known: Work up of patient with amenorrhea, galactorrhea, and hyperprolactinemia 