[Comparison of non-HPLC 1 alpha, 25(OH)2D assay system with the HPLC method]

Recently, a method not requiring high performance liquid chromatography (HPLC) has been developed (Amersham Inc., U.K) for the measurement of levels of 1 alpha, 25(OH)2D, which demonstrates the most potent physiological effect among the metabolites of vitamin D. Until recently, purification of 1 alpha, 25(OH)2D fraction with HPLC has been considered indispensable prior to radioreceptor assay of this metabolite. Therefore, we used the Amersham assay system to determine whether it is possible to correctly measure the level of 1 alpha, 25(OH)2D without the HPLC process. The procedures we used were to extract the serum with an organic solvent, followed by fractionation of vitamin D metabolites through an LH-20 column. The products with or without the use of HPLC were submitted to radioreceptor assay using chick embryo intestinal receptors. As a result, it was found that (1) Separation and yield were improved by changing the column size, (1) Serum values 1 alpha, 25 (OH)2D in healthy subjects obtained by HPLC and non-HPLC methods were in good agreement with the theoretical values. Although the values thus obtained in patients with chronic renal insufficiency (with or without dialysis) were somewhat lower than the theoretical values, the result was consistent because there was no significant difference between the tow sets of measured values, and the correlation coefficient was r = 0.990. (3) Variations within the assay were CV = 16.5% for HPLC group and CV = 21.4% for non-HPLC group.(ABSTRACT TRUNCATED AT 250 WORDS)