A Simple Modified Method for Urine Citrate Determination

Objective: Measurement of urine citrate is used to assess the risk of urinary stone for-mation. We attempted to perform a modified, cheap and reliable colorimetric method for the analysis of urinary citrate and to compare it with an enzymatic method. Methods: Urine citrate levels were measured with a colorimetric method and a com-mercially available enzymatic method in patients with urolithiasis (n=50) and in healthy controls (n=44). We modified the colorimetric method which was first developed by Millan with a subsequent modification of Lewis. Performance characteristics of the methods were compared. Results: Urine citrate levels of patients were lower as compared to controls by both of the methods. However, the difference between patients and controls was insignificant by enzymatic method, whereas significant by in-house method (P≤0.05). Within-run imprecisions for colorimetric method were 2.1%, 3.06 % and 0.52 % and 3.19%, 0.91% and 2.99 % for enzymatic method in low, intermediate and high citrate containing uri-nary pools; between-day imprecisions of the methods were 11.16%, 14.74%, 9.36%, an