LBSAT292 A Rare Case Of Co-existent Grave's Disease Complicated By Non Medullary Thyroid Carcinoma And Primary Hyperparathyroidism In A Young Male

INTRODUCTION: The relationship between medullary thyroid carcinoma and parathyroid adenoma is well recognized and has been described in connection with MEN syndromes; however, co-existing Grave's disease with underlying non medullary thyroid carcinoma and primary hyperparathyroidism remains a rare phenomenon. The basis of this entity remains yet to be deciphered. With this case we wish to highlight that synchronous abnormalities of thyroid and parathyroid should always be considered and further testing to evaluate for underlying genetic abnormalities should be offered on a case by case basis. In addition, since both Grave's disease and hyperparathyroidism contribute to hypercalcemia, their interplay must be considered in interpretation of serum calcium and parathyroid function. CASE PRESENTATION: A 44 year old male with no significant medical history presented to the PCP with chest pain and dyspnea on exertion. EKG showed sinus tachycardia. Labs showed Calcium 11.1 mg/dl (8.6 - 10.3), Albumin 4 g/dl (3.5 - 5.7), TSH <0. 010 uIU/ml (0.27 - 4.20), Free T4 3.71 ng/dl (0.5 - 1.6). Repeat labs confirmed these findings. Additional tests included: PTH 105.9 pg/ml (12 - 88), Ionized calcium 6.4 mg/dl (4.5-5.4), TPO antibody positive and TSI antibody positive. Propranolol was started and Endocrinology was consulted. Thyroid ultrasound showed hyperechoic gland and 24 hour radio-active Iodine uptake was abnormally increased to 67.8% (8 - 33%), consistent with Grave's disease. Options for treatment were discussed. Decision was made to start Methimazole to achieve euthyroid state followed by repeat PTH (104.1 pg/ml) and Calcium (calcium 10.6 mg/dL) testing. Due to persistent hypercalcemia with inappropriately elevated PTH, surgical intervention was planned. Pre-operative localization studies were ordered: thyroid ultrasound showed two hypoechoic thyroid nodules in the superior right thyroid lobe and inferior left thyroid lobe, and sestamibi scan did not show any focus of increased activity to suggest a parathyroid adenoma. Total thyroidectomy with parathyroid exploration was planned. Surgical pathology was consistent with three foci of papillary thyroid carcinoma measuring 5 mm, 3 mm and 1 mm in size in the right thyroid lobe and right inferior parathyroid adenoma. Post-operatively, thyroid hormonal supplementation was initiated and thyroid and parathyroid function panel normalized. DISCUSSION: Our patient had concurrent non medullary thyroid carcinoma and primary hyperparathyroidism. Concurrent thyroid carcinoma should always be considered in patients presenting with parathyroid abnormalities, and a complete pre-surgical screening evaluation must be done. Genetic testing should be considered. And since hyperthyroidism and hyperparathyroidism both can lead to hypercalcemia, their interplay must be considered in interpretation of serum calcium and parathyroid function. Presentation: Saturday, June 11, 2022 1:00 p.m. - 3:00 p.m.