Unreliable visual estimation of the incidence and amount of turbidity, hemolysis, and icterus in serum from hospitalized patients.

We examined the frequency of occurrence for turbidity, hemolysis, or icterus in 2599 serum samples submitted for chemistry testing in an acute-care general hospital. Each specimen was compared visually with full-color photographs of adulterated serum, and designated as either "0" (containing no interferent), or trace, 1+, 2+, 3+, 4+, or 5+. Visible interferents (1+ or greater) were thought to be present in 838 (31%) of the specimens (icterus, 525; hemolysis, 244; lipemia, 69). To assess the accuracy of such visual grading, we determined the concentration of triglycerides, hemoglobin, or bilirubin in the specimens considered to be contaminated. There was little agreement between the actual concentration of each interferent and the assigned grade of turbidity, hemolysis, or icterus, confirming the unreliability of human visual estimation of these potentially interfering substances.