More on anticoagulant adjustment from Heather DeVries: There is more to our story on adjusting sodium citrate for high hematocrits. We have a pediatric patient who is getting multiple draws, for multiple assays, throughout the day. Sometimes there is PT and/or PTT , but sometimes not. The techs are confused as to when the draw must be in a corrected tube. We all understand how the citrate is affecting the results due to its relationship with calcium, but what about when an anti-Xa level is drawn, or an ATIII (antithrombin, AT ) functional? If those are the only assays ordered, must the tube be corrected? The patient's hematocrit has been hovering around 60%. Thanks, Heather.
Thank you, Heather, and I hope your staff and pathologist are communicating with the child's care team to ensure they are not causing a hospital acquired anemia. I'll go out on a limb in the absence of empirical outcomes data and agree with your staff that any clot-based assay is likely to be influenced by the anticoagulant to plasma ratio, but not an immunoassay or a chromogenic substrate assay. If your antithrombin assay is a chromogenic assay, you would be safe to use a standard draw. Perhaps one of our participants knows of a study supporting this conclusion.
