Vitamin D and Graves' disease: a meta-analysis update.

ABSTRACT

The association between vitamin D levels and Graves' disease is not well studied. This update review aims to further analyze the relationship in order to provide an actual view of estimating the risk. We searched for the publications on vitamin D and Graves' disease in English or Chinese on PubMed, EMBASE, Chinese National Knowledge Infrastructure, China Biology Medical and Wanfang databases. The standardized mean difference (SMD) and 95% confidence interval (CI) were calculated for the vitamin D levels. Pooled odds ratio (OR) and 95% CI were calculated for vitamin D deficiency. We also performed sensitivity analysis and meta-regression. Combining effect sizes from 26 studies for Graves' disease as an outcome found a pooled effect of SMD = -0.77 (95% CI -1.12, -0.42; p < 0.001) favoring the low vitamin D level by the random effect analysis. The meta-regression found assay method had the definite influence on heterogeneity (p = 0.048). The patients with Graves' disease were more likely to be deficient in vitamin D compared to the controls (OR = 2.24, 95% CI 1.31, 3.81) with a high heterogeneity (I2 = 84.1%, p < 0.001). We further confirmed that low vitamin D status may increase the risk of Graves' disease.