Fig. 1From: Implications of standardization of serum 25-hydroxyvitamin D data for the evaluation of vitamin D status in Germany, including a temporal analysisCalibration study results used to standardize serum samples from GNHIES98. 25(OH)D, Serum 25-hydroxyvitamin D; CLIA, Chemiluminescent immunoassay; LC-MS/MS, Liquid chromatography-tandem mass spectrometry; GNHIES98, German National Health Interview and Examination Survey 1998Back to article page