Comparison of HPLC, RIA, ELISA methods in determining 25-OH vit D levels by the means of test performance criteria

Objective: 25-OH Vitamin D measurement is the most common and valuable method when identifying Vitamin D status. On this account precise measurement of 25 OH Vitamin D is highly important. In this study, method evaluation process has been done for HPLC method, the method has been made valid and it is compared with ELISA and RIA methods respectively.Material and Methods: After doing method validation study for 25-OH Vitamin D, HPLC is regarded as reference method. Then HPLC is compared with ELISA and RIA methods respectively.Results: Repeatability study has been done in 2 levels, interassay and intraassay %CV values, for 25-OH Vitamin D. for interassay repeatability process, levels of %CV are found as 5.93 and 2.37. For intraassay repeatability process, levels of %CV are found as 7.00 and 2.60. Result of recovery assay is found as mean of %95 (%93-96). When comparing HPLC to ELISA, R value is found 0.36 and p value is found 0.022; when comparing HPLC to RIA, R value is found 0.22 and p value is found 0.174.Conclusions: In this study which regards HPLC method as reference, it is found that RIA method is statistically differs significant from HPLC method and lacks precision in clinic studies while ELISA method is statistically insignificant from HPLC method but half precise.Keywords: 25-OH Vitamin D, HPLC, ELISA, RIA, Method Comparison