Spectral properties of bilirubin can interfere with co-oximetry measurements. Bilirubin also interferes with peroxidase coupled reactions such as for total cholesterol and triglycerides, and in Jaffe or enzymatic creatinine measurements. Total bilirubin concentrations of less than 10 g/dL do not generally impact testing to a significant degree. Package inserts delineate the icteric index threshold for which each test is considered valid. In a retrospective study performed by an academic medical center, in what percent of laboratory studies did the icteric index exceed the package insert thresholds?
0.14% of clinical chemistry assays performed showed icteric interference that exceeded the package insert icteric index threshold, and half of all such incidences were ascribed to a small cohort of patients.
Mainali S, Merrill AE, Krasowski MD. Frequency of icteric interference in clinical chemistry laboratory tests and causes of severe icterus. Practical laboratory medicine. 2021 Nov 1;27:e00259.
Contributed by Kristine Nanagas, MD