Preoperative 25(OH)D≥75 Nmol/L is associated with a reduced risk of hypocalcemia after parathyroidectomy: evidence...

Postoperative hypocalcemia is a significant complication in patients with primary hyperparathyroidism (PHPT) after parathyroidectomy. While vitamin D supplementation is a commonly used as a preventive strategy, the optimal preoperative 25-hydroxyvitamin D [25(OH)D] level for this population remains unclear. Some guidelines recommend 25(OH)D >75 nmol/L as the optimal threshold, while others suggest that correcting vitamin D deficiency, typically defined as achieving levels above 50 nmol/L, is sufficient.

This meta-analysis aimed to determine whether preoperative 25(OH)D levels ≥50 nmol/L or ≥75 nmol/L are necessary to reduce the risk of hypocalcemia in PHPT patients after parathyroidectomy, in order to provide information for evidence-based prevention strategies.

PubMed, Embase, Web of Science, Scopus and the Cochrane Library were systematically searched from inception to December 2024, without language restrictions.

Eight observational studies (N = 4,120) met the inclusion criteria of 1917 initially identified records.

Two investigators independently extracted data from eligible studies, including characteristics of study design, preoperative baselines of 25(OH)D levels, calcium and PTH levels, postoperative calcium levels, and hypocalcemia outcomes. The meta-analysis was conducted by the inverse variance model. Risk Ratio (RR) were used for dichotomous outcome event, standardized mean difference (SMD) was calculated for continuous data. Data was presented with 95% confidence interval (CI). The I2 index was used for heterogeneity assessment.

PHPT patients with preoperative 25(OH)D levels 50-75 nmol/L showed no significant reduction in hypocalcemia risk compared to those <50 nmol/L (RR 0.65, 95% CI 0.39-1.07, I2 = 72%, p = 0.028). However, PHPT patients with preoperative 25(OH)D levels ≥75 nmol/L exhibited 44% lower risk of postoperative hypocalcemia compared to those with 25(OH)D levels <75 nmol/L (RR 0.56, 95% CI, 0.32-0.99; I2 = 65%;p = 0.02). In addition, compared to patients with preoperative 25(OH)D levels<75 nmol/L, patients with preoperative 25(OH)D levels > 75 nmol/L showed no significant increase in preoperative serum calcium levels (SMD 0.01, 95% CI -0.29-0.32, I2 = 92.3%, p<0.001).

Preoperative 25(OH)D levels ≥75 nmol/L are associated with a reduced risk of hypocalcemia after parathyroidectomy, whereas levels between 50 and 75 nmol/L are not. Notably, achieving a 25(OH)D level ≥75 nmol/L is not associated with increased preoperative serum calcium levels, supporting its safety in clinical practice.