[A method for quantitative dertermination of 20-keto steroids in urine during the use of a 3 alpha-, 20 beta-hydroxysteroid: NAD oxidoreductase (author's transl)].

A method is described for the quantitative determination of 20-ketosteroids in urine during the application of a 3alpha, 20beta-hydroxysteroid: NAD oxidoreductase. In the presence of NADH H+ the enzyme catalyses in an "equimolar" developing reaction the reduction of 20-keto groups of C-21 steroids giving 20 beta-alcohols. The measurable NADH H+ consumption is a measure for the quantity of those 20-ketosteroids present in the reaction mixture. The 3alpha-hydroxysteroid: NAD oxidoreductase activity of the enzyme does not influence the specificity of the method to determine the 20-ketosteroids because,-under the present extraction and purification conditions-those 3alpha-hydroxy-5alpha-androstan derivatives are not reaching the reaction mixture of determination. The demands towards the criterions of reliability (correctness and exactitude) come to be fulfilled by this method.