Independent Predictors of Symptomatic Hypocalcemia Following Thyroidectomy: Distinguishing Biochemical and Symptomatic Hypocalcemia

Background/Objectives: Postoperative hypocalcemia is the most common complication following thyroidectomy; however, previous studies have largely relied on biochemical definitions without distinguishing symptomatic hypocalcemia from asymptomatic biochemical abnormalities. This study aimed to identify the independent predictors of symptomatic postoperative hypocalcemia. Methods: This retrospective single-center study included 245 adult patients who underwent thyroidectomy between January 2017 and December 2022. Patients were classified as normocalcemic (n = 88), asymptomatic biochemical hypocalcemic (n = 87), or symptomatic hypocalcemic (n = 70) according to calcium status within the first 72 postoperative hours. Demographic, surgical, biochemical, ultrasonographic, cytological, and histopathological variables were analyzed. Independent predictors were identified using multivariable logistic regression. Results: Symptomatic hypocalcemia occurred more frequently after bilateral total thyroidectomy with central neck dissection (p = 0.001). Patients with symptomatic hypocalcemia had lower preoperative serum calcium and lower postoperative albumin and parathyroid hormone levels than the other groups (all p < 0.05). Although high-risk FNAB cytology and malignant histopathology were associated with hypocalcemia in univariate analyses, neither remained independently predictive after adjustment. Bilateral total thyroidectomy with central neck dissection (adjusted OR 6.63, 95% CI 1.68–26.11; p = 0.007) and lower preoperative serum calcium (adjusted OR 0.46, 95% CI 0.22–0.94; p = 0.036) were independent predictors of symptomatic hypocalcemia after thyroidectomy. Conclusions: Symptomatic postoperative hypocalcemia should be considered a distinct clinical outcome rather than merely a biochemical abnormality. Bilateral total thyroidectomy with central neck dissection and lower preoperative serum calcium independently predicted symptomatic hypocalcemia, whereas ultrasonographic findings, FNAB cytology, histopathological diagnosis, and incidental parathyroidectomy did not. Although the absence of perioperative vitamin D and magnesium measurements is an important limitation, the identified predictors may provide clinically useful information for perioperative risk stratification.