MON-369 Calcium Gone Crazy: Recurrent Hypercalcemia in Patient with History of Hypoparathyroidism

Introduction Patients with post-operative hypoparathyroidism mostly require Calcium supplements and Calcitriol with goal of maintaining calcium levels in low normal range. However, calcium balance can further be dysregulated by other factors including renal failure in patients with otherwise stable levels. We present a case of recurrent symptomatic hypercalcemia leading to multiple hospital visits in a patient with otherwise stable longstanding post-operative hypoparathyroidism that was precipitated after episode of Acute Renal Failure. Case Presentation 71 Year old male with past medical history of Atrial fibrillation, Hypertension, Primary Hyperparathyroidism status post Parathyroidectomy (Parathyroid hyperplasia with removal of 3/12 glands) in 2003 with subsequent Hypoparathyroidism presented with lethargy and confusion few days after cardioversion attempt for atrial fibrillation. He was noted to have bradycardia and hypotension post procedure which improved subsequently. His medications included Calcitriol 0.25 mcg twice daily and Calcium Carbonate 1.25 grams twice daily. His Calcium had remained stable over the years on this regimen. On presentation, he was found to have elevated corrected calcium of 12.5 mg/dl and Acute Renal failure with Creatinine of 8.3 mg/dl which was normal 1 week prior. He underwent hydration and subsequently required few sessions of hemodialysis with improvement in kidney function and further hemodialysis was not needed. On discharge his corrected calcium was 8.6 mg/dl and Creatinine was 3.9 mg/dl. His Calcitriol and Calcium were resumed on discharge. However, 3 weeks later he presented again with lethargy and calcium was again elevated at 14.8 mg/dl. All other workup for hypercalcemia including PTHRP, Bone marrow biopsy, Serum electrophoresis were negative. Subsequently, he had 2 more admissions for hypercalcemia and 1 admission for hypocalcemia within 1 month. Finally his calcium levels stabilized with reduced dose of Calcitriol and Calcium with close weekly monitoring initially as outpatient. Discussion In advancing kidney disease, the kidneys are no longer able to increase urine calcium excretion, and this removes an important safety mechanism to prevent calcium excess in patients with Chronic kidney disease. In patients with hypoparathyroidism on Calcitriol and Calcium supplements, renal failure may offset the calcium balance leading to dysregulation and erratic levels with increased tendency towards hypercalcemia. Conclusion Acute Renal Failure may lead to hypercalcemia in patients with otherwise stable levels. However, limited understanding of calcium balance/ regulation in renal failure, especially in setting of hypoparathyroidism further complicates the situation and may lead to difficult titration of medications.