Comparison of high performance liquid chromatography, radio immunoassay and electrochemiluminescence immunoassay for quantification of serum 25 hydroxy vitamin D.

OBJECTIVE: To compare the performance of radioimmunoassay (RIA) with high-performance liquid chromatography (HPLC) and electrochemiluminescence (ECLIA) for the quantification of vitamin D (25OHD). METHODS: HPLC method for the determination of 25OHD in human biological samples was developed and compared in terms of accuracy and precision with a commercially available RIA assay. Performance of RIA assay with ECLIA technology for 25OHD analysis was further compared. RESULTS: Median 25OHD levels with HPLC vs. RIA were 50.1nmol/L (IQ=17.7-199.4nmol/L) and 51.1nmol/L (IQ=12.5-187.2nmol/L) respectively, whereas median 25OHD concentration with RIA vs. ECLIA was 32.4nmol/L (9.98-199.7nmol/L) and 29.9nmol/L (4.9-214.6nmol/L), respectively. Comparison data for HPLC vs. RIA showed RIA=-1.13+1.01 (HPLC) (RMSE=11.2nmol/L) and for RIA vs. ECLIA revealed, ECLIA=3.21+0.9 (RIA) (RMSE9.6nmol/L). CONCLUSION: Acceptable correlation was observed among HPLC and RIA and also with RIA and ECLIA in quantification of 25OHD