A timely question from Frank Cragg, MD, Nova Scotia Health. "Hi, I have the IL 750 ready to implement but am getting conflicting information on how much hemolysis to allow. Please help. Regards, Frank Cragg MD, FRCPC [C].
Hello, Dr. Cragg, and thank you for your question, which I've forwarded to several experts. Although more comments may arrive over the next hours or days, here is what we've received as of 11-18-21.
From Dean Willett, Precision BioLogic Inc. Dean writes, "The 50 series TOP instruments have pre-set hemolysis settings specific to individual tests. The settings are based on the claims in each reagent’s instructions for use and differ from assay to assay. I’m thinking Dr. Cragg's options are to go with the settings as programmed into each test, then validate higher levels internally for each desired assay and update the limits. He may choose to turn off the preanalytical alerts."
Marc Lauzon, Precision BioLogic VP of Sales concurs. Marc writes, "As Dean indicated, a lab can set up and validate differing levels of the individual hemolysis levels referred to for each assay as is assigned on the ACL TOP x50 series or turn them off."
Frequent contributor and international expert Bob Gosselin writes, "IL has earned FDA approval for hemoglobin on their instruments [510k 150877], but the allowable limit is somewhat arbitrary. Here's a reference that partially addresses this issue: Kitchen S, Adcock DM, Dauer R, et al. International Council for Standardization in Haematology [ICSH] recommendations for processing of blood samples for coagulation testing. Int J Lab Hematol. 2021;43:1272–83, available from Wiley Press. Their guidance addresses alerts and cites references that provide established limits or acceptability thresholds.
But one must be cognizant of the "rare ducks": in-vivo hemolysis not related to phlebotomy such as in sepsis and poisoning, or stroma-free therapeutic hemoglobin products. For the latter, most studies have been halted due to their nitric oxide scavenging, but they still are available internationally. For possible in-vivo hemolysis, I stroll over to chemistry to check out their specimen. If it too is hemolyzed, then the potassium level is the tiebreaker. Increased LDH and normal K+ are seen when it is in-vivo hemolysis and vice-versa for in-vitro hemolysis. BG"
I also spoke with coag expert Dave McGlasson, Clot Club, who echoes the information of Dean, Marc, and Bob, and adds that, as indicated in the Kitchen article, any visible hemolysis may indicate platelet activation and clot-based coagulation test shortening associated with the release of phospholipid microparticles. Please return to this post, as I anticipate additional comments.
Some 12-2-21 comments from Russell "Rusty" Higgins, MD: "I spoke with the IL folks. They use the interference limits for hemolysis, icterus, and lipemia [HIL] from their product inserts. They didn’t specifically say but implied that the limits were sent at 10% to 15% over baseline for each assay. The HIL limits were determined for the most recently approved reagents, so if you use older reagents the interference may not be appropriate.
We have the HIL module on the ACL TOP but haven’t started using it yet because we wanted to understand the impact first. I am attaching a careful study from Mayo on the ACL TOP 750—but I need to dig for the supplementary tables for the specific reagents used. The impact of hemolysis on DRVVT piqued my interest. It is strange that they didn’t study fibrinogen [QFA], as I discovered that this is still measured at 405 nm.
On 12-15-21, Dr. Higgins added, "The IL representative confirmed that their 750 system is approved for icterus as well as hemolysis and lipemia."
Dr. Higgins' reference is Seheult JN, Dalenberg D, Sridharan MR, et al. Revisiting the effects of spectral interfering substances in optical-end-point coagulation assays. Int J Lab Hematol. 2021;43:1181–90. https://doi. org/10.1111/ijlh.13465, available from Wiley Press.