Multiple endocrine neoplasia type 1 (MEN1) syndrome is characterized by the presence of hyperplastic or neoplastic tumors in the parathyroid, pituitary, and gastroenteropancreatic endocrine tissues. The presence of lesions in at least two out of the three glands (pituitary, parathyroid, and pancreas) is indicative of MEN1 syndrome. Medullary thyroid carcinoma (MTC) is a type of tumor that originates from the parafollicular C cells of the thyroid gland. It is frequently found as part of MEN2 syndrome. MEN1 with MTC is a relatively uncommon occurrence. We report a rare case of MTC that later on developed parathyroid carcinoma, pituitary microadenoma, pancreatic neuroendocrine tumor (NET), and duodenal NET. The case was identified as part of MEN1 syndrome using exome sequencing and somatostatin receptor-based functional imaging 68 Ga-DOTATATE positron emission tomography/computed tomography was employed for exploring theranostic strategy in the management of the patient.