1985 Volume 76 Issue 12 Pages 1848-1854
A method for enzymatic determination of urinary citrate using citrate lyase is described. The optimum pH is 7.2 and the addition of zinc ion is found to activate the reaction, but the influence of pH and zinc ion on the reaction velocity is reduced in proportion to increase of citrate lyase. The effect of the Tris HCl buffer concentration on reaction velocity is also studied, and high concentrations of the Tris HCl buffer are found to inhibit the reaction.
The recovery rates of citrate added to urine ranged from 98.5% to 103% and the coefficient of variation of triplicate assay is 3.1%.
The urinary citrate excretion in healthy volunteers are 397±159 and 474±209mg/day (mean±SD) for 66 males and 23 females, respectively.
Since this method is highly precise and convenient, it may be readily adopted as a routine clinical examination.
