Hemolysis has no influence on routine coagulation tests in subjects without anticoagulant therapy - a referral Romanian emergency hospital laboratory experience

Abstract

The aim of this study was to determine the rate of hemolyzed specimens sent to our laboratory for coagulation testing, assess the interference of hemolysis on coagulation for patients without anticoagulant therapy and to determine the reference intervals for PT, INR and aPTT for our laboratory in order to test our own limitations. Methods: To determine the hemolysis rate, 1,689 specimens were evaluated on a visual scale and with the hemolysis icterus lipemia (HYL) test on Architect c4000 instrument. 125 blood samples collected from subjects without anticoagulant therapy were hemolyzed in vitro and the PT, INR and aPTT results were compared before and after hemolysis.To determine reference intervals (RI) for PT, INR and aPTT in our population, 125 apparently healthy human subjects (according to CLSI C28-A2) were enrolled and tests were performed on Sysmex CS 2000i, using Siemens reagents. Results: Out of 1,689 samples, 9.46% were assessed as hemolyzed by the visual scale, while HYL test showed a 6.63% hemolysis rate. We found a shortening of 0.1s for PT, a diminution with 0.01 units for INR and a prolongation with 0.9s for aPTT from in vitro hemolyzed compared to non-lyzed samples. As to the reference intervals, we obtained in our laboratory versus reagents producer: for PT 9.8-13.9 s vs 9.8-12.1 s, and for aPTT 19.1-31.5s vs 23-31.9 s respectively; 28.38% more PT results and 13.44% more aPTT results were within range when we used local laboratory RI, compared to the manufacturer’s RI. Conclusions: The rate of hemolyzed coagulation samples in our laboratory is higher than the rate found in the literature. Nevertheless, for patients without anticoagulant therapy hemolyzed samples should be processed. Using our own reference interval leads to a significant reduced number of abnormal results.

Letter to the Editor

“…Although a small number of laboratories completed our survey, it is clear that some aspects of the preanalytical process are more closely evaluated than others. For instance, as we demonstrated in a previous study, hemolysis has influence on routine coagulation tests, but does not have any clinical significance in subjects without anticoagulant therapy (8). The EFLM WG-PRE has provided the tools for evaluating the preanalytical phase.…”

Quality Control Strategy for Automated CBC: A Laboratory Point of View Deducted from an Internal Study Organised in an Emergency Laboratory

“…Sigma scores for defects that are correctly identified and for those defects that remain undetected by laboratory staff were similar. In a study concerning hemolysis evaluation with a visual scale and an automated hemolysis test, visual inspection overestimated the hemolysis rate in coagulation sample tubes (15). Both clinicians and laboratory staff should ensure the right samples are used for the correct patient investigation.…”