RF30 | PSAT136 Gitelman Syndrome and Primary Hyperparathyroidism, a Case Report

INTRODUCTION: Gitelman syndrome, also known as familial hypokalemia-hypomagnesemia, is a rare autosomal recessive disorder that impairs the sodium chloride cotransporter (NCC) and magnesium channels in the renal distal convoluted tubule, causing salt-losing tubulopathy. It is characterized by hypokalemia, hypomagnesemia, hypocalciuria, and secondary hyperaldosteronism. Although hypocalciuria is a distinctive characteristic of Gitelman syndrome, it seldom can cause any change in the total plasma calcium level. Thus, the occurrence of hypercalcemia would need further investigation. CASE PRESENTATION: We reported a case of a 36-year-old normotensive man with a past medical history significant for bipolar depression disorder and a history of chronic atrial fibrillation secondary to chronic hypokalemia, hypomagnesemia, and mild hypercalcemia. He was diagnosed with Gitelman syndrome. However, he was noncompliant with spironolactone, potassium, and magnesium supplementation. He suffered a motor vehicle accident, and on presentation to the emergency room, he was found with a serum potassium of 2.5 mEq/L (reference value 3.5-5.1), serum magnesium of 0.8 mEq/L (reference value 1.6-2.6), total serum calcium of 11.3 mEq/L (reference value 8.4-10.2), and serum phosphorus of 2.7 (reference value 2.5-4.5 mg/dl). Random urine potassium was 122.1 mEq/L, and intact parathyroid hormone was 144 pg/mL (reference value 14-65). His CT neck scan showed a 1.5 cm nodule inferior to the right thyroid lobe pole consistent with an inferior parathyroid adenoma. However, a parathyroid radionuclide scan using technetium-99m MIBI showed no radiopharmaceutical localization for parathyroid adenoma. CONCLUSION: Hypercalcemia is extremely rare in Gitelman syndrome, offset by the action of concomitant hypomagnesemia. Our case shows the importance of investigating other causes of hypercalcemia, such as primary hyperparathyroidism in patients with Gitelman syndrome. To our knowledge, Gitelman syndrome and primary hyperparathyroidism are an extremely rare association that is present in our case. Presentation: Saturday, June 11, 2022 1:00 p.m. - 3:00 p.m., Monday, June 13, 2022 12:48 p.m. - 12:53 p.m.