Effect of ketones and glucose on the estimation of urinary creatinine: implications for microalbuminuria screening

The influence of acetoacetate, 3-hydroxybutyrate, and glucose on the assay of urinary creatinine by Jaffe-type and enzymatic methods was studied in vitro. Acetoacetate (greater than or equal to 5 mmol l-1) led to significant overestimation of low concentration urinary creatinine measured by an end-point and a kinetic Jaffe reaction, but neither 3-hydroxybutyrate nor glucose influenced these reactions. None of the metabolites interfered with an enzymatic creatininase assay. It is recommended that, when employing the urinary albumin/creatinine ratio to screen for microalbuminuria in diabetes mellitus, an enzymatic method be used to measure creatinine in Ketostix positive samples, particularly those that are dilute or obtained from patients with a low lean body mass.