ENZYMATIC RATE METHOD FOR MEASURING CHOLESTEROL IN SERUM

  • 1 January 1976
    • journal article
    • research article
    • Vol. 22  (12) , 2042-2045
Abstract
An enzymatic rate assay is described for measuring cholesterol in [human] serum. Cholesterol is analyzed by mixing 5 .mu.l of sample with a reagent consisting of cholesterol esterase, cholesterol oxidase, catalase, acetylacetone, methanol and hydroxypolyethoxydodecane in a ammonium phosphate buffer at pH 7.0. The rate of increase in absorbance of the dihydrolutidine product is measured at 37.degree. C and 405 nm. The change in absorbance between 4 and 10 min is used to calculate the cholesterol concentrations by using simultaneously determined free cholesterol standards. The change is linearly related to cholesterol concentration up to 4 g/l. Samples containing bilirubin up to 200 mg/l, uric acid up to 200 mg/l, and Hb up to 1 g/l, or certain drugs (clofibrate, phenobarbital, nicotinic acid, salicylate, Ketochol, and Ovral) gave no interference. Ascorbic acid added to serum caused a positive interference. Lipemic samples gave values that were slightly lower than did the method of Abell et al., used for comparison. The kinetic assay used, compared with the method of Abell et al., the enzymatic assay used with Abbott''s Bichromatic Analyzer and the Technicon SMA 12/60 enzymatic procedure gave correlation coefficients of 0.992, 0.985 and 0.986, respectively.

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