From high PTH to hungry bone syndrome: insights into post-parathyroidectomy hypocalcemia in patients with ESRD

Background: Hungry bone syndrome (HBS) is a severe, potentially life-threatening complication of parathyroidectomy in patients with refractory secondary or tertiary hyperparathyroidism (SHPT/THPT) due to end-stage renal disease (ESRD). It is characterized by persistent, profound hypocalcemia secondary to rapid bone remineralization. The epidemiology, predictors, and optimal management of HBS remain incompletely defined. Case: We report two cases of HBS following parathyroidectomy in ESRD patients. The first, a 22-year-old man with ESRD from minimal change disease and THPT, developed severe postoperative hypocalcemia (2.6 mg/dL) requiring ICU monitoring, intravenous calcium infusion, and high-dose oral calcium and calcitriol, with gradual recovery. The second, a 47-year-old man with ESRD from polycystic kidney disease and SHPT, presented a month post-parathyroidectomy with critically low calcium (3.5 mg/dL), persistent symptoms despite supplementation. Discussion: We review the pathophysiology of hyperparathyroidism in CKD, the mechanisms of HBS, and evidence on risk factors—including high preoperative alkaline phosphatase, elevated PTH, low calcium, and prolonged dialysis. We are suggesting preoperative treatment to prevent HBS in high-risk patients such as preoperative optimization with vitamin D analogs, calcium, cinacalcet, and pamidronate, and highlight current management approaches emphasizing aggressive calcium and calcitriol replacement. Keywords: hungry bone syndrome, parathyroidectomy, secondary hyperparathyroidism, tertiary hyperparathyroidism, end-stage renal disease, hypocalcemia.