Postoperative hypocalcemia after parathyroidectomy: distinguishing suppressive hypoparathyroidism from hungry bone syndrome

Postoperative hypocalcemia remains a clinically relevant complication after parathyroid surgery and is traditionally considered a single entity. However, patients who develop postoperative hypocalcemia after minimally invasive parathyroidectomy (MIP) may exhibit distinct biochemical profiles and clinical courses, suggesting that postoperative hypocalcemia does not represent a single postoperative entity. This study aimed to classify postoperative hypocalcemia after MIP in primary hyperparathyroidism (PHPT) and to identify distinct clinical subtypes and associated risk factors. This retrospective study included 126 patients who underwent MIP for histopathologically confirmed parathyroid adenoma. Patients were classified according to postoperative biochemical phenotype as suppressive hypoparathyroidism or hungry bone syndrome (HBS). Preoperative clinical, biochemical, and radiological variables were analyzed. Univariate and multivariate logistic regression analyses were performed to identify independent predictors of each hypocalcemia subtype. Suppressive hypoparathyroidism developed in 39 patients (31%), whereas HBS occurred in 15 patients (12%). In multivariate analysis, lower preoperative phosphorus levels (OR = 0.21, p = 0.029) and higher femoral neck T-scores (OR = 2.10, p = 0.008) independently predicted suppressive hypoparathyroidism. In contrast, elevated preoperative parathyroid hormone levels (OR = 1.006, p = 0.009) and lower femoral neck T-scores (OR = 0.35, p = 0.022) were independent predictors of HBS. Postoperative hypocalcemia following MIP comprises at least two distinct clinical entities. Suppressive hypoparathyroidism represents a unique, self-limited postoperative phenotype distinct from hungry bone syndrome, with important implications for postoperative management and follow-up.