Abstract Disclosure: N. Abrahimi: None. A. Abrahimi: None. Background: Hypocalcemia secondary to hypoparathyroidism is a known complication for patients who undergo thyroidectomy. (1) Additionally, patients who undergo bariatric surgery are similarly at risk for developing hypocalcemia. (2) Clinical Case: 52-year-old female with past medical history of thyroid carcinoma status post total thyroidectomy complicated by post operative hypoparathyroidism and history of gastric bypass presented to the hospital with paresthesia and fatigue. On presentation, calcium measured at 6.9 mg/dL, EKG showed Qtc prolongation at 503. Physical exam was positive for Chvostek sign and Trousseau sign. The patient received 1 g of intravenous calcium gluconate and was admitted to medicine for management of symptomatic hypocalcemia. Calcium initially improved to 8.2 mg/dL with a subsequent drop to 7.5 mg/dL. An additional 1 g of intravenous calcium gluconate was administered, calcium then corrected to 8.0 mg/dL, symptoms and Qtc prolongation resolved. The patient endorsed compliance with daily calcium supplementation of oral calcitriol prior to presentation. Prior to discharge, calcitriol dosage was increased, and patient was instructed to follow up calcium levels in one week outpatient with endocrinologist. Conclusion: Bariatric surgery, specifically gastric bypass or Roux-en-Y bypass reduces absorption of vitamin D and calcium as the primary sites for absorption are bypassed. (3) Although not commonly studied, severe hypocalcemia is linked to an increased risk for development of serious cardiac arrhythmias. (4) This emphasizes the importance of close calcium monitoring in patient with history of bariatric surgery and hypoparathyroidism.