The Effect of Sample Hemolysis on Cardiac Troponin I and T Assays

To the Editor: Cardiac troponin I and T (cTnI and cTnT)1 assays are used for the diagnosis of acute myocardial infarction (AMI) (1). Recent improvements in these assays have lowered the imprecision and detection limit so that the assays meet guidelines for using the 99th percentile cutoff concentration. These new cardiac troponin assays have the potential to improve clinical practice by earlier diagnosis, improved risk stratification, and improved monitoring of patients. They also, however, increase the number of true- and false-positive results for patients suspected of AMI (2). Hemolysis is the most common preanalytical interference encountered in the routine laboratory. I tested the effect of sample hemolysis on 1 contemporary and 1 high-sensitivity (hs) cardiac troponin assay. I prepared hemolysate from erythrocytes that had been washed 3 times with 0.9% saline. After the final centrifugation, the cells were diluted with an equal volume of distilled water, thoroughly mixed, and lysed by freezing. I measured cTnI using the Ortho Clinical Diagnostics TnI ES assay (contemporary) on the Vitros® 5600 Integrated System and cTnT using the Roche TnT hs assay on the Elecsys E170 immunoassay system, which was part of a Modular integrated system. To measure the effect of hemolysate on cTnI and hs cTnT, thawed hemolysate …