Association between Circulating Vitamin D Level and Urolithiasis: A Systematic Review and Meta-Analysis

Many studies compared the serum/plasma 1,25 dihydroxyvitamin D3 (1,25(OH)2D) and 25 hydroxyvitamin D3 (25(OH)D) between people with and without nephrolithiasis, and their results were conflicting. After systematically searching PubMed, Web of Science, The Cochrane Library, CNKI, and the Wanfang Database, we conducted a meta-analysis. Thirty-two observational studies involving 23,228 participants were included. Meta-analysis of these studies showed that of stone formers (SFs), calcium SFs had significantly higher concentrations of 1,25(OH)2D (weighted mean difference (WMD), 10.19 pg/mL; 95% confidence interval (CI), 4.31–16.07; p = 0.0007 and WMD, 11.28 pg/mL; 95% CI, 4.07–18.50; p = 0.002, respectively) than non-stone formers, while the levels of 25(OH)D (WMD, 0.88 ng/mL; 95% CI, −1.04–2.80; p = 0.37 and WMD, −0.63 ng/mL; 95% CI, −2.72–1.47; p = 0.56, respectively) are similar. Compared with controls and normocalciuria SFs, hypercalciuria SFs had increased circulating 1,25(OH)2D (WMD, 9.41 pg/mL; 95% CI, 0.15–18.67; p = 0.05 and WMD, 2.75 pg/mL; 95% CI, −0.20–5.69; p = 0.07, respectively) and markedly higher 25(OH)D (WMD, 5.02 ng/mL; 95% CI, 0.99–9.06; p = 0.01 and WMD, 5.02 ng/mL; 95% CI, 2.14–7.90; p = 0.0006, respectively). Normocalciuria SFs had elevated 1,25(OH)2D level (WMD, 6.85 pg/mL; 95% CI, −5.00–18.71; p = 0.26) and comparable 25(OH)D (WMD, 0.94 ng/mL; 95% CI, −3.55–5.43; p = 0.68). Sensitivity analysis generated similar results. Current evidence suggests that increased circulating 1,25(OH)2D is associated with urinary stones and a higher level of circulating 25(OH)D is significantly associated with hypercalciuria urolithiasis. Further studies are still needed to reconfirm and clarify the role of vitamin D in the pathogenesis of stones.