Handling of hemolyzed serum samples in clinical chemistry laboratories: the Nordic hemolysis project

Abstract

Background Some clinical chemistry measurement methods are vulnerable to interference if hemolyzed serum samples are used. The aims of this study were: (1) to obtain updated information about how hemolysis affects clinical chemistry test results on different instrument platforms used in Nordic laboratories, and (2) to obtain data on how test results from hemolyzed samples are reported in Nordic laboratories. Methods Four identical samples containing different degrees of hemolysis were prepared and distributed to 145 laboratories in the Nordic countries. The laboratories were asked to measure the concentration of cell-free hemoglobin (Hb), together with 15 clinical chemistry analytes. In addition, the laboratories completed a questionnaire about how hemolyzed samples are handled and reported. Results Automated detection of hemolysis in all routine patient samples was used by 63% of laboratories, and 88% had written procedures on how to handle hemolyzed samples. The different instrument platforms measured comparable mean Hb concentrations in the four samples. For most analytes, hemolysis caused a homogenous degree of interference regardless of the instrument platform used, except for alkaline phosphatase (ALP), bilirubin (total) and creatine kinase (CK). The recommended cut-off points for rejection of a result varied substantially between the manufacturers. The laboratories differed in how they reported test results, even when they used the same type of instrument. Conclusions Most of the analytes were homogeneously affected by hemolysis, regardless of the instrument used. There is large variation, however, between the laboratories on how they report test results from hemolyzed samples, even when they use the same type of instrument.

A Reference chart for clinical biochemical tests of hemolyzed serum samples

“…For hemolysis interference, the results of quantitative analysis are largely consistent with previous reports, including changes in LDH, potassium, CK, CK-MB, and some other analytes. 12,18,19 However, several previous studies used freeze-and-thaw or mechanical trauma without assessing the achievement of cell lysis. 12,16,20,21 In these studies, the extent of hemolysis was solely determined from the hemolytic index measured by the machine.…”

Hemolysis interference in 10 coagulation assays on an instrument with viscosity‐based, chromogenic, and turbidimetric clot detection

“…The Architect measures hemolysis at 500, 524, 572, 604, 628, 660, and 804 nm and returns a numerical value that approximately corresponds to g/L of free hemoglobin. The Architect hemolysis readings have proved to exhibit acceptable accuracy and reproducibility . Also, the used Architect instrument participates in an external quality program for HIL from EQUALIS AB .…”