Vitamin D Supplementation to Prevent Post-Thyroidectomy Hypocalcemia

Hypocalcemia is the most common complication following thyroidectomy. Previous studies yielded inconsistent results on whether vitamin D₃ prevents postoperative hypocalcemia and were conducted in non-European countries with different dietary habits and baseline vitamin D levels. Therefore, we explored the effect of preoperative vitamin D₃ on post-thyroidectomy hypocalcemia in a Dutch cohort.

Patients undergoing thyroidectomy between 2023 and 2025 received 100,000 IU vitamin D₃ 1 week before surgery ("vitamin D group") and were compared to a historical cohort (2019-2022) without vitamin D₃ supplementation ("control group"). Outcomes included incidence of hypocalcemia (albumin-adjusted calcium < 2.00 mmol/L), need for postoperative supplementation, time until normocalcemia, length of hospital stay, and readmissions.

Fifty patients received preoperative vitamin D₃ and were compared to 154 controls (82.8% female, median age: 55 years [IQR: 43-66]). Vitamin D₃ supplementation was associated with a reduced risk of biochemical hypocalcemia at all postoperative time points (OR 0.28, 95% CI: 0.11-0.68, p = 0.005), corresponding to a number needed to treat of five patients to prevent one case of hypocalcemia. As compared to controls, the need for postoperative supplementation and time to recover from hypocalcemia were lower in the vitamin D group (32.0% vs. 53.9%, p = 0.007; and 0 [0-2] vs. 3 [0-11] days, p = 0.002, respectively). No differences were observed in length of hospital stay or readmissions.

Although larger randomized trials are needed to confirm these observations, preoperative vitamin D₃ was associated with a significant reduction in post-thyroidectomy hypocalcemia in this observational cohort study. Given its low costs, this intervention may be considered for routine implementation in thyroidectomy patients.