Planck T, et al. - The authors performed this study to compare the vitamin D levels in patients with Graves disease (GD) with the general population and to correlate the vitamin D levels with laboratory and clinical parameters in GD. In addition, they aimed to investigate the genetic variation in genes involved in the vitamin D metabolism and their association with GD. Compared to the general population, patients with GD had lower vitamin D levels. The vitamin D levels, however, did not affect the laboratory or clinical parameters of GD. Single nucleotide polymorphisms (SNPs) in the vitamin D receptor (VDR) affected the risk of GD through mechanisms other than reducing the vitamin D levels.