Anne D’ Agostino asks, “Should we reject hemolyzed samples from someone in DIC?” The simple answer is “do not reject,” because the hemolysis is likely intravascular, reflecting DIC‘s microangiopathic hemolytic anemia [MAHA].
But to elaborate, there’s no foolproof way to differentiate intravascular [in vivo] hemolysis from spurious [in vitro] hemolysis, the consequence of specimen collection or management error, by laboratory means. Perhaps the most reliable approach is to ensure the specimen is collected by non-traumatic venipuncture and not through a vascular access device. If the “clean” specimen is hemolyzed, you have no choice but to test and report with a comment. A study, Montaruli B, Guiotto C, Cosseddu D. Influence of hemolysis, icterus and lipemia on coagulation tests as performed on Cobas t511 new analyzer. Blood Coagul Fibrinolysis. 2020;31:48-54. doi: 10.1097/MBC.0000000000000873. PMID: 31789660 indicates that moderate hemolysis prolongs the PTT and reduces fibrinogen and antithrombin compared to a non-hemolyzed specimen, but while the variances are statistically significant, they are not clinically significant. Conversely, the authors determined that the D-dimer is both statistically and clinically lowered by free hemoglobin’s optical interference.
One set of investigators has attempted to employ hemolysis corrective formulas to distinguish in vivo from in vitro hemolysis but could make no firm recommendation: Lippi G, Avanzini P, Pavesi F, et al. Studies on in vitro hemolysis and utility of corrective formulas for reporting results on hemolyzed specimens. Biochem Med (Zagreb). 2011;21:297-305. doi: 10.11613/bm.2011.040. PMID: 22420244.
Most automated clinical chemistry analyzers and several automated coagulometers now offer optical serum or plasma hemolysis, icterus, and lipemia [HIL] estimation, enabling the release of valid results based on HIL interference levels upon individual analytes. As reported in the Montaruli study, visible hemolysis is defined as the presence of cell-free plasma hemoglobin at a concentration of over 300 mg/dL, a level that may not indicate optical interference of clot-based assays. However, visible hemolysis may indicate the activation of procoagulants and platelets through venipuncture turbulence or excessive specimen agitation, so unless the hemolysis is intravascular, the results should not be reported.
I’ve requested comments from “the usual suspects,” so watch for additional information.