Refractory Hungry Bone Syndrome in ESKD Following Parathyroidectomy

Introduction: Hungry bone syndrome (HBS) commonly occurs after parathyroidectomy in ESKD patients with secondary hyperparathyroidism. Severe hypocalcemia, hypophosphatemia and hypomagnesemia result from rapid calcium influx into bones. This case highlights the unique challenges of managing refractory HBS. Case Description: 39-year-old female with ESKD due to lupus on hemodialysis and osteoporosis underwent a subtotal parathyroidectomy for secondary hyperparathyroidism. Her intraoperative PTH was 3,342 pg/mL and her postoperative PTH was 174. She developed severe, symptomatic hypocalcemia with serum total calcium (Ca) 5.2-7.6 mg/dL; ionized calcium (iCa) 2.79-4.25 mg/dL despite calcium carbonate 800 mg 5x/day, calcitriol 3 mcg TID, and calcium drip 0.5 mg/kg/hr. She was hospitalized for 19 days with persistent hypocalcemia and hypophosphatemia requiring a calcium drip, elemental calcium, calcitriol, paricalcitol with dialysis, oral phosphate, and high calcium (3 Ca++) dialysate bath. Medications were spaced to prevent calcium-phosphorus chelation and improve absorption. Calcium administered >1hr before meals, phosphorus, or other interfering meds. She was discharged on calcitriol 4 mcg BID, calcium carbonate liquid solution 2000 mg Q4H, sodium phosphate 500 mg QID, paricalcitol 10 mcg with dialysis and ergocalciferol 50,000 units weekly with instruction to space calcium and phosphorus by >1hr and continue high calcium dialysate. Three days later, she returned with pain, muscle spasms, paresthesia, and numbness. Labs showed Ca 5.2 mg/dL, iCa 2.45 mg/dL, phosphorus 1.8 mg/dL, alkaline phosphatase 1,095 u/L, PTH 160 pg/mL. High calcium dialysate rapidly improved symptoms. She had not been spacing calcium and phosphorus doses. Her prior regimen was restarted (oral/IV calcium, phosphate, calcitriol, and high calcium dialysis). She was on day 8 of her second hospitalization and nearing discharge at the time of submission. Discussion: Post-parathyroidectomy hypocalcemia is common and usually resolves in days. HBS can cause prolonged hypocalcemia and hypophosphatemia lasting months or years. This case shows HBS may persist despite aggressive therapy. It emphasizes calcium repletion to avoid mealtime and phosphorus to prevent chelation and poor absorption. Finally, rapid symptom resolution can be achieved in patients on hemodialysis by utilizing a high calcium dialysate bath.