Differences that can be observed in various methods against the mean of all the methods

Difference of various 25-hydroxyvitamin D (25[OH]D) methods against the mean of all the methods, including liquid chromatography tandem mass spectrometry (LC-MS/MS) and popularly used immunoassay methods. HPLC indicates high-pressure liquid chromatography; IDS, immunodiagnostic systems; IDS EIA, immunodiagnostic systems and manual enzymatic immunoassay; IDS iSYS, immunodiagnostic systems and new automated immunoassay; IDS RIA, immunodiagnostic systems and radioimmunoassay; radioimmunoassay (RIA).