SAT-767 Pre-emptive Parathyroidectomy and Hungry Bone Syndrome in Renal Transplant Candidates: A Management Conundrum

Abstract Disclosure: F.H. Antoni: None. S. Khosla: None. F. Mousavi: None. S. Gandhi: None. S. Sen: None. M. Akunjee: None. Background: Management of severe secondary hyperparathyroidism (SHPTH) in ESRD, when preparing for renal transplant, is challenging. Parathyroid hormone (PTH) levels need optimization to prevent adverse graft and patient outcomes post-transplant. Medications including intravenous calcimimetics like etelcalcetide are used to lower PTH. However, any direct action of etelcalcetide on bone turnover and mineralization is unclear. While no guidelines exist, parathyroidectomy (PTX) is usually considered if PTH >800 pg/mL despite medications, and/or in presence of other sequelae. Post PTX, there is a high risk for severe hypocalcemia secondary to Hungry Bone Syndrome (HBS). We describe a case of protracted HBS to highlight treatment complexities. Clinical Case: 52-year-old male on hemodialysis (HD) was referred for severe SHPTH management prior to renal transplant. Despite IV etelcalcetide, PTH ranged from 1174-2574 pg/mL (normal [nl] 15-65 pg/mL) with low corrected calcium (CCa) ranging 8.0-8.8 mg/dL (nl 8.9-10.5 mg/dL), normal 1,25-(OH)2-vitamin D 24 pg/mL (nl 18-72 pg/mL), high alkaline phosphatase 159 U/L (nl 43-130 U/L) and low 25-OH-Vitamin D3 ranging 20.8-27.5 ng/mL (nl > 30 ng/mL). DXA did not show bone loss. Sestamibi scan showed bilateral parathyroid adenomas. During PTX, intraoperative PTH declined from 1791 pg/mL to 522.5 pg/mL. Pathology confirmed parathyroid hyperplasia in both glands. Hospital course was complicated by severe refractory hypocalcemia. Post-operative day 1-2, mean CCa was 6.73 mg/dL (range 6.2-7.4 mg/dL) and day 3-14, mean CCa was 7.9 mg/dL (range 6.8-9.4mg/dL). Patient required continuous calcium gluconate drip or boluses for 15 days, almost daily high calcium baths in HD, as well as oral calcium carbonate (CaCO3), calcitriol, and cholecalciferol. Phosphorus ranged 3.2-6.5 mg/dL (nl 2.5-4.5 mg/dL), magnesium levels were normal and patient remained hemodynamically stable without arrhythmias or prolonged QTc throughout his 18-day hospitalization. After improvement of PTH to 234 pg/mL and CCa 8.5 mg/dL, patient was discharged with CaCO3 1950 mg TID, calcium acetate 1334 mg TID, calcitriol 0.5 mcg BID and weekly cholecalciferol 50,000 IU. Conclusion: This case of profound, persistent hypocalcemia highlights the difficulty in managing ESRD with SHPTH. Currently there are no standardized tools to predict the risk of severe HBS with PTX before renal transplant versus severe hypercalcemia without PTX after renal transplant. Optimal calcium and vitamin D levels prior to PTX are not well-established. Normal bone density and use of calcimimetics in this case did not preclude patient from developing HBS. This suggests further investigation is needed to evaluate the ideal perioperative management strategy. Post-PTX, a higher level of care should be anticipated to include hemodynamic monitoring, aggressive calcium repletion and multidisciplinary care. Presentation: Saturday, July 12, 2025