Descarga: Interference in Coagulation Testing: Focus on Spurious Hemolysis, Icterus, and Lipemia
Archivo: tromboembolia-venosa/tvp/STH 2013 Interference in Coagulation Testing.pdf
The chance that errors might jeopardize the quality of testing is inherently present throughout the total testing process, especially in the preanalytical phase. In the coagulation laboratory, as well as in other areas of diagnostic testing, spurious hemolysis, icteria, and lipemia in test samples represent by far the leading diagnostic challenges.Interferenceinhemostasistestingduetospurioushemolysisisattributedto both analytical and biologic elements, namely high absorbance ofcell-free hemoglobin at wavelengths used by optical instrumentation and release of both cytoplasmatic and plasma membrane molecules (e.g., tissue factor, proteases, phospholipids, and ADP) that can spuriously activate blood coagulation and platelets. The interference attributable to hyperbilirubinemia is mostly due to spectral overlap, whereas that of hypertriglyceridemia mainly reflects elements of light scatter and volume displacement as wellasdirectinterferenceoflipidparticleswithhemostasis.Inpracticalterms,spurious hemolysisreflectsamoregeneralizedprocessofendothelialandbloodcelldamage,so that test results on spuriously hemolyzed specimens should be systematically suppressed. The bias attributable to hyperbilirubinemia is less significant using modern coagulometers equipped with dedicated wavelengths (i.e., with readings at 650 nm or above),sothattestresultsinsampleswithabilirubinconcentrationupto20mg/dLcan stillbeanalyticallyreliable.Theinterferenceobservedinlipemicsamplesismostevident with readings using wavelengths lower than 500 nm and can hence be prevented with readingsat650 nmorabove,and/orusinghigherdilutionsof thetestsample,orcanbe abated in high hypertriglyceridemic specimens (i.e., > 1,000 mg/dL) using high speed microcentrifugation or lipid extraction with organic solvents such as fluorine-chlorinatedhydrocarbon,orlipid-clearingagentssuchasLipoClear(StatSpinInc.,Norwood,MA) and n-hexane
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