Enzyme conversion immunoassay for determining total homocysteine in plasma or serum

A rapid and precise immunoassay for quantification of total homocysteine in blood samples is presented. The method avoids the use of radioisotopes and chromatographic separations and relies on enzymatic conversion of homocysteine to S-adenosyl-L-homocysteine, followed by quantification of S-adenosyl-L-homocysteine by an enzyme-linked immunoassay in microtiter format. The within- and between-assay imprecision is < 6% and 8%, respectively, and results by the method show good correlation with those by HPLC. Including controls and calibrators in duplicates, 82 samples can be analyzed within 2.5 h. The procedure can be fully automated.