Incidental parathyroidectomy during thyroid surgery and postoperative hypocalcemia: a multicenter retrospective cohort study

Abstract

Background Postoperative hypocalcemia is the most frequent metabolic complication of thyroidectomy, and incidental parathyroidectomy (IPT) is a commonly cited but incompletely characterized contributor. Despite a substantial published literature, the independent clinical impact of IPT on postoperative calcium homeostasis remains debated, and multicenter data from high-volume endocrine surgery settings in Saudi Arabia are lacking. Methods A retrospective multicenter cohort study was conducted across high-volume endocrine surgery units in Saudi Arabia between January 2020 and December 2024. A total of 455 patients who underwent total or subtotal thyroidectomy were included. IPT was defined histopathologically. Predictors of IPT and of postoperative hypocalcemia were assessed using pre-specified multivariable logistic regression, with cluster-robust standard errors accounting for the multicenter structure. Adjusted odds ratios (aORs) with 95% confidence intervals are reported. Results IPT was confirmed in 145 of 455 patients (31.9%). In a pre-specified multivariable model, age ≥60 years was associated with IPT with conventional standard errors (aOR 1.72, 95% CI 1.04–2.85; p = 0.035) but not after accounting for clustering by operating surgeon (aOR 1.72, 95% CI 0.70–4.24; p = 0.24); no variable was a robust independent predictor. When postoperative hypocalcemia was modeled directly, IPT was not associated with it (aOR 0.94, 95% CI 0.44–2.00; p = 0.87), whereas total thyroidectomy was the dominant predictor (aOR 4.82, 95% CI 1.44–16.07; p = 0.011). Preoperative parathyroid hormone was available for only 112 of 455 patients (24.6%) and, using an appropriate non-parametric test, did not differ significantly by IPT status (4.00 ± 1.98 vs. 5.73 ± 4.88 pg/mL; p = 0.14, Mann–Whitney U test). IPT was not associated with calcium supplementation requirement or readmission for hypocalcemia. Conclusions IPT occurred in nearly one-third of patients but did not predict postoperative hypocalcemia; the extent of surgery, specifically total thyroidectomy, was the principal determinant of postoperative calcium disturbance. Age and preoperative parathyroid hormone were not robust independent correlates once clustering and appropriate testing were applied. These results support universal postoperative calcium monitoring after total thyroidectomy rather than reliance on histologic parathyroid findings.