<prompt> A 35 year old male known case of MEN 1 presents to OPD with urinary stones and increased serum calcium. Next investigation to be done is?Urinary MetanephrineSecretin studySerum calcitonin levels72 hour prolonged fasting  <response>: Patient of MEN 1 have Pituitary adenoma Parathyroid adenoma-Most common and earliest manifestation is hyperparathyroidism with symptomatic hypercalcemia. Pancreatic adenoma Gastrinomainsulinoma In diagnosed cases of MEN1 where nephrocalcinosis is documented, evaluation of pancreatic adenoma is impoant. The most common pancreatic adenoma in MEN 1 is ZES and hence for evaluation of ZES, secretin study is done. Subsequently 72 hours fasting test and endoscopic ultrasound will be useful for evaluation of insulinoma. The incidence of ZES in MEN I is 70 versus insulinoma being 10. Surgical management is Definitive treatment of choice If a MEN 2A patient has the same presentation, then calcitonin levels and urinary metanephrine levels shall be performed In MEN IIA, incidence of medullary carcinoma thyroid 90 is more than that of pheochromocytoma 20-35. 