Background: Enzymatic creatinine assays are routinely used in clinical laboratories to provide more accurate estimated glomerular filtration rates and to avoid a perceived lack of analytical specificity associated with picrate (Jaffe) methods. Negative interferences with the enzymatic creatinine assay, which we noted in several patients on dopamine or dobutamine, prompted our further investigation into interference of catecholamines with enzymatic methods.
Methods: Spiked solutions of dopamine, dobutamine, epinephrine, and norepinephrine were added to pooled sera at catecholamine concentrations consistent with clinically relevant dosing.
Objective: In this study, we determined the assay performance criteria necessary to produce acceptable results for >or=98% of neonate bilirubin samples collected by capillary heel-stick.
Study Design And Methods: We determined serum free hemoglobin levels in 151 heel-stick serum samples to determine the hemolysis level. We then tested the effect of hemolysis on total bilirubin levels determined by four commercially available assays.