Establishing hemolysis and lipemia acceptance thresholds for clinical chemistry tests
Claire E Knezevic1, Mary Ann Ness1, Polly Hoi Ting Tsang1
1Department of Pathology, Johns Hopkins Medical Institutes, Baltimore, MD, United States.
Background:
A key component of laboratory medicine is the evaluation of specimen suitability for downstream analytical testing. Accurate identification and characterization of the impact of interferents on clinical chemistry analytes is important for patient care. To empirically assess the influence of hemolysis and lipemia on clinical chemistry tests analyzed on a Roche cobas® c701 system, we evaluated serum pools spiked with increasing concentrations of hemolysate and Intralipid®.
Methods:
Using an interferent acceptance threshold of within ± 10% of the non-hemolyzed or non-lipemic results, 31 routine chemistry analytes were evaluated.
Results:
The majority of analytes were determined to have the same or very similar acceptability thresholds as those listed in the vendor package insert. However, several analytes resulted in new thresholds that deviated from manufacturer recommendations (9 higher and 2 lower for lipemia, 7 higher and 6 lower for hemolysis). Samples with high enzyme activities (LDH, ALT, AST, ALP, and CK) were observed to tolerate higher levels of hemolysis, and tiered hemolysis thresholds were established for these enzymes. Independent evaluation of indices is recommended to enable thoughtful implementation of specimen quality criteria and to provide guidance to laboratorians and providers on the nature of these interferences.
