Irene Regan writes that despite doing major literature searches there seems to be no consensus regarding what coagulation results should be released when there is a suspicion of in vivo hemolysis such as in disseminated intravascular coagulation (DIC), when the samples are grossly haemolysed. Currently, Irene issues a fibrinogen (Clauss) and in this case she generally confirms this using a correction with normal plasma due to haemolysed nature of the sample or because the fibrinogen is extremely low. Do you have any advise?
Hello, Irene, this is an interesting question, and it is true there is little documentation about what specific interferences arise in hemolysis. The experts routinely advise a recollect when there is visible hemolysis resulting from an improper collection, however there is nothing you can do about in vivo hemolysis. Hemolysis implies both platelet and coagulation factor activation, generating unreliable results across the board. Additionally, hemolysis interferes with the determination of the clotting endpoint or with chromogenic assays in optical instrumentation.
My suggestion is to employ an electro-mechanical clot-based instrument for your coagulation determinations and append a comment warning of possible interference. When diagnosing DIC, check the package insert for your D-dimer kit to learn the manufacturer’s claims regarding the degree of hemolysis interference. Do the same for any chromogenic assays you may perform.
This is an excellent question, and I await comments from other contributors, including possible references they may have run across. Thank you.
Distinguishing in vivo hemolysis from in vitro hemolysis is
Distinguishing in vivo hemolysis from in vitro hemolysis is clinically very important so that those suffering in vivo hemolysis are not denied potentially life saving treatments. In our own small test series investigating short APTTs, some 10% of test samples seemed to represent in vivo effects. Whilst not the same as in vivo vs in vitro hemolysis, it is clear that at least a portion of samples rejected by laboratories as hemolysed come from patients suffering in vivo hemolysis. At the same time, the effects of in vivo and in vitro hemolysis in terms of interferences on coagulation tests will probably be similar. Also important to recognise is that interferences are not restricted to coagulation tests. An excellent small book on the subject of hemolysis is available: “In Vitro and In Vivo Hemolysis: An unresolved dispute in laboratory medicine (Patient Safety)” by Giuseppe Lippi.
Our own study regarding free hemoglobin and bilirubin influe
Our own study regarding free hemoglobin and bilirubin influence on APTT and anti-Xa assay would be published in Arch Pathol Lab Med soon…
Excellent review about hemolysis influence on coagulation as
Excellent review about hemolysis influence on coagulation assay: Giuseppe Lippi, Mario Plebani, Emmanuel J. Favaloro. Interference in Coagulation Testing: Focus on Spurious Hemolysis, Icterus, and Lipemia. Semin Thromb Hemost. 2013 Apr;39(3):258-66.
From full-text version there were 2 cited evidences, that fibrinogen is decreased due to hemolysis on MDA 180 and Behring Coagulation System analyzers.
We did our own small study a few years ago, but only in rega
We did our own small study a few years ago, but only in regards to PT/INRs and APTTs. We found that normal or prolonged PTs are mostly unaffected by even moderate amounts of hemolysis. However, with APTTs we found that there is a positive bias even with slight amounts of hemolysis. This APTT bias worsens with higher results, so that those of us still using APTTs to monitor heparin therapy should take notice.
Of course, any specimen that appears to be a difficult draw should be rejected for clotting tests, if only to avoid the effects of activated platelets. Hemolysis by itself may not be affecting the test.
Scott