FT4 is a novel indicator for risk assessment of severe hypocalcemia following parathyroidectomy.

Objective: To analyze the risk factors associated with the development of severe hypocalcemia (SH) in patients who have undergone parathyroidectomy (PTX).

Methods: This research involved patients with chronic kidney disease-secondary hyperparathyroidism who underwent PTX between June 1, 2021, and May 31, 2023. SH was characterized by a serum total calcium (tCa) level below 1.8 mmol/L. This study aimed to analyze differences in preoperative laboratory findings and clinical manifestations between patients with and without SH. Logistic regression analysis was used to identify potential risk factors associated with the development of SH.

Results: The incidence of SH was 23% (n = 176). Significant differences were observed in free thyroxine (FT4), free triiodothyronine, alanine aminotransferase, osteocalcin, tCa, alkaline phosphatase (ALP), C-terminal cross-linked telopeptide of type I collagen, and parathyroid hormone between the SH and non-SH groups. The three independent risk factors for SH were tCa [odds ratio (OR) 0.063, 95% confidence interval (95% CI) 0.006-0.663], ALP (OR 1.003, 95% CI 1.001-1.005), and FT4 (OR 0.439, 95%CI 0.310-0.621). The area under the curve, sensitivity, specificity, and overall accuracy of this model were 0.904 (95% CI 0.856-0.952), 46.3%(95% CI 32.0%-61.3%), 94.8% (95% CI 89.7%-97.5%), and 83.5% (95% CI 77.3%-88.3%), respectively.

Conclusion: The preoperative level of FT4 plays a crucial role in predicting the risk of SH after PTX. The combined FT4-ALP-tCa model demonstrates the ability to predict SH risk, providing valuable insights for customizing calcium supplementation strategies and improving clinical decision-making.