Does Hemolysis Affect the Anti-Xa?

Here is another question from my friend and colleague, Vicki Cardone, Hematology Supervisor at Children’s Hospital of Alabama, just across the street from my own University of Alabama Hospital:

Would a hemolyzed sample cause the anti-Xa value to be falsely decreased as it would give a stronger color reaction, or am I just way off?

Thanks, Vicki

Hi, Vicki. I checked out your question with David McGlasson at Wilford Hall Hospital in San Antonio. He has experimented with the assay and found that the color associated with hemolysis does not change the outcome of the chromogenic anti-Xa heparin assay.
However, hemolysis indicates in vitro platelet activation, releasing platelet factor 4. PF4 neutralizes heparin, so even though the color may not interfere, the heparin result is unreliable.
Because of activation, coagulation specimens with visible hemolysis must be consistently rejected. Geo