Independent Predictors of Hungry Bone Syndrome After Parathyroidectomy for Primary Hyperparathyroidism: Insights from a Large Cohort Study

Background/Objectives: Hungry bone syndrome (HBS) is a clinically significant metabolic complication following parathyroidectomy for primary hyperparathyroidism (PHPT), characterized by profound and prolonged hypocalcemia resulting from rapid skeletal remineralization. Although multiple risk factors have been proposed, published data remain inconsistent regarding the most reliable predictors. This study aimed to evaluate potential risk factors associated with the development of HBS and to clarify controversial findings reported in the literature. Methods: Patients who underwent surgery for PHPT between January 2019 and May 2025 were retrospectively analyzed. Individuals who developed HBS were compared with those who did not in terms of clinical, biochemical, and surgical parameters. Results: HBS occurred in 4.7% of patients. Those in the HBS group exhibited significantly higher preoperative serum calcium, parathyroid hormone, alkaline phosphatase (ALP), and Ca/P ratio, while phosphate, vitamin D, and T-scores were significantly lower. Postoperative day 1 calcium levels were also markedly reduced. Multivariate analysis identified increased ALP, low T-score, concomitant thyroid surgery, and decreased postoperative day 1 calcium as independent predictors. A postoperative day 1 calcium cutoff of 8.6 mg/dL demonstrated strong predictive accuracy. Conclusions: HBS is more commonly observed in patients with low bone density and high bone turnover. Patients with these risk factors should be considered high-risk and closely monitored in the early postoperative period to enable prompt intervention and prevent severe complications.