Case Presentation: A 31-year-old man with chronic kidney disease following failed renal transplant on hemodialysis (HD) for 3 years via arteriovenous fistula and tertiary hyperparathyroidism presented for admission following a 3.5-gland parathyroidectomy. Intraoperative PTH levels dropped from 2280 to 503 pg/mL. Postoperatively, he presented with hypocalcemia (total calcium 5.9 mg/dL; corrected calcium 6.3 mg/dL) and alkaline phosphatase (ALP) of 760 IU/L. He was started on 4 g of oral calcium carbonate, 1 mcg calcitriol, and 2 g intravenous push (IVP) calcium gluconate. The patient was started on a continuous infusion of calcium gluconate at 2 g/hr. At the standard concentration of 10 g/L, this infusion required 2 peripheral IV infusions running at 100 mL/hr each. He developed shortness of breath, productive cough, and fluid overload that required daily HD on hospital days 2 and 3. On hospital day 4, the calcium infusion was changed to a concentration of 20 g/L. This was infused at a rate of 75 mL/hr and then slowly titrated down to 10 mL/h over the next 6 days. After changing the concentration of the calcium infusion, he remained without significant fluid overload and received HD on his routine schedule on hospital days 5, 7, and 9. Throughout his hospitalization he reported substantial relief from his chronic bone pain and did not experience symptoms of hypocalcemia, such as muscle cramping, numbness, or tingling. On hospital day 10, his treatment was interrupted for one day for the patient to see his children. The patient was readmitted to the hospital and was resumed on calcium infusion at 30 mL/hr and received HD on his usual schedule. He was asymptomatic throughout his second admission. The patient was discharged home from his second admission on hospital day 9.
Discussion: Hungry bone syndrome is a rare but potentially life-threatening complication of parathyroidectomy, characterized by a severe decline in serum calcium levels (less than 2.1 mmol/L) and prolonged hypocalcemia lasting more than four days post-surgery (1). This can manifest as muscle spasms, tetany, and cardiac arrhythmias. This case highlights key risk factors for hungry bone syndrome, including younger age (≤45 years), elevated alkaline phosphatase (>420 IU), high iPTH (>1000 pg/mL), and absence of preoperative hypercalcemia (>10.2 mg/dL) (2). The syndrome occurs in 25-90% of patients with radiological evidence of bone disease due to hyperparathyroidism and approximately 25% of patients on dialysis (3,4).
Conclusions: Given the complexities of managing hungry bone syndrome, patients with these risk factors should be closely monitored and treated postoperatively to mitigate the risk of symptomatic hypocalcemia and reduce hospital stays. For patients with renal failure on HD, a higher concentration of calcium gluconate infusion at a lower volume should be used to minimize complications of fluid overload.
