PSAT226 Management of a Patient with Primary Hyperparathyroidism by Discontinuation of Hydrochlorothiazide: Preventing the Need for Surgical Management

INTRODUCTION: Recurrent or persistent primary hyperparathyroidism has been reported in 2-5% of patients after the initial operation. Reoperations have been associated with significant complications. The aim of this presentation is to highlight the importance of medical management prior to proceeding to surgery. CASE PRESENTATION: A 72-year-old man with a past medical history of coronary artery disease and asthma was found to have hypercalcemia and osteoporosis and was diagnosed with primary hyperparathyroidism in 2009. He had no family history of hypercalcemia. Three parathyroid glands were removed in 2010 and his parathyroid hormone normalized immediately after the surgery. About 10 years after the surgery, he developed hypertension and calcium-type kidney stones. He was treated with losartan 50 mg daily and hydrochlorothiazide 12.5 mg daily. One year later his calcium level was 11.1 mg/dL, parathyroid hormone (PTH) 70 pg/mL, 25-OH vitamin D level 44 ng/mL and creatinine was 0.8 mg/dL. A CT scan demonstrated a lesion measuring 1.3×1.1×1.6 cm which was suspicious for an ectopic parathyroid adenoma in the left ascending aorta. He was scheduled for surgical exploration and removal of the parathyroid adenoma for recurrence of primary hyperparathyroidism. Prior to the surgery, the patient was evaluated in our office for a second opinion. Physical exam and review of systems were unremarkable. Thyroid ultrasound showed a heterogeneous thyroid with no thyroid nodules or parathyroid adenoma. Adequate hydration was recommended and since his blood pressure was well-controlled, hydrochlorothiazide was discontinued. Surgery was canceled to confirm that the hypercalcemia was due to hydrochlorothiazide rather than hyperparathyroidism. After 4 months of follow-up, his blood pressure remained controlled on monotherapy with Losartan, and the repeat calcium level was 9.6 mg/dL with a PTH level of 44 pg/mL. CONCLUSION: Post-surgical patients with a history of primary hyperparathyroidism, when presenting with hypercalcemia can get misdiagnosed as recurrent or persistent primary hyperparathyroidism; therefore, other causes of hypercalcemia including medications that may affect the calcium level and its metabolism should be considered and excluded prior to surgical management. Presentation: Saturday, June 11, 2022 1:00 p.m. - 3:00 p.m.