Hypocalcemia remains the most frequent complication following thyroidectomy. We hypothesized that pre-operative supplementation with cholecalciferol may mitigate this risk.
This was a randomised, double-blind, placebo-controlled trial comparing cholecalciferol (300000 units) with matched placebo administered orally seven days prior to thyroidectomy. Primary outcome was incidence of post-operative hypocalcaemia (corrected calcium <2.1mmol/L). Secondary outcomes were supplementation requirements and length of hospital stay (LOS). Outcomes were further analysed with in a Cox regression model based on first postoperative day parathyroid hormone (PTH) levels.
Out of 160 patients who were randomised, 150 underwent thyroidectomy and were analysed. The incidence of post-operative hypocalcaemia in the cholecalciferol group was 29%, compared to 38% in the placebo group (p=0.23). When stratified by post-operative PTH level, the hazard ratio for hypocalcemia was 0.56 (95% CI 0.32-0.98; p=0.04) in the cholecalciferol group. In 115 patients with normal PTH (≥10pg/mL), a lower rate of hypocalcaemia (10% vs 24%; p=0.05) and reduced requirement for calcium or calcitriol supplementation (8% vs 24%; p=0.02) was observed in the cholecalciferol group. In 35 patients with low-PTH <10pg/mL), rate of hypocalcaemia was lower (60% vs 93%; p=0.03) and LOS was shorter (2 vs 3 days; p=0.04) in the cholecalciferol group when compared to placebo. Cholecalciferol was well tolerated, and the rate of hypercalcaemia was not increased compared to placebo.
Pre-treatment with high dose cholecalciferol improves clinical outcomes following thyroidectomy. The low and normal post-operative PTH groups had different rates of hypocalcaemia, which blunted the magnitude of treatment effect when considered as a whole cohort, but significant reduction in morbidity was observed in both groups.