The frequency of hypocalcaemia among patients who underwent total thyroidectomy: A prospective cohort study

Abstract

Objective: Hypocalcaemia is the most common early metabolic complication following total thyroidectomy, primarily due to parathyroid dysfunction. To determine the frequency, severity, and predictors of post-thyroidectomy hypocalcaemia in a prospective cohort.

Methods: A prospective observational study was conducted over 18 months (January 2023–June 2024) on 217 consecutive adult patients undergoing total thyroidectomy at a tertiary care centre in Iraq. Serum calcium (Ca²⁺) and intact parathyroid hormone (iPTH) were measured preoperatively and at 6, 24, and 48 hours postoperatively. iPTH was measured using ELISA. Symptomatic hypocalcaemia was defined as serum calcium (Ca²⁺) <8.0 mg/dL with neuromuscular symptoms. Multivariate logistic regression identified independent predictors.

Results: The overall incidence of biochemical hypocalcaemia was 38.7% (n=84); symptomatic hypocalcaemia occurred in 17.1% (n=37). Permanent hypocalcaemia occurred in 1.4% (n=3). An iPTH cutoff of <10 pg./mL (derived from ROC analysis) predicted symptomatic hypocalcaemia with high accuracy (AUC 0.93). Independent predictors included low 6-hour iPTH (OR 8.2, p<0.001), female sex (OR 2.1, p=0.03), and central neck dissection (CND) (OR 3.4, p=0.002).

Conclusion: Hypocalcaemia is frequent but predominantly transient. Early iPTH measurement—even via ELISA- is feasible and effective in resource-limited settings for early risk stratification. Early postoperative iPTH measurement accurately predicts hypocalcaemia and enables targeted calcium supplementation, reducing unnecessary treatment and hospital stay.