Thecause ofturbidity inlyophilised plasmas and itseffects on coagulation tests

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Aims:Toinvestigate thecauseofturbidity inreconstituted lyophilised plasmasand todetermine itseffect oncoagulometers. Methods:The turbidities of20normal plasmasand16reconstituted lyophilised plasmasweredetermined bycomparing a 1in4 dilution indistilled waterwitha standardsuspension in an Aminco Fluorocolorimeter (American Instrument Co) innephelometric mode.The turbidities offiveotherplasmas weredeterminedbefore andafter lyophilisation. The turbidcomponentsoffreshandreconstituted lyophilised plasmas werestudied usingelectron microscopy. Theeffects of turbidity on fivetypesofcoagulometer weredetermined byaddingvarying concentrations of a turbidity enhancing material. Results: Reconstituted lyophilised plasmasweremoreturbidthannormalplasmas,because ofagglomerated liposomes. Serumdepleted ofchylomicrons andvery lowdensity lipoproteins wasnotrendered moreturbid bylyophilisation. Threeout offivetypesofautomated coagulometer testedgaveactivated partial thromboplastin timeswhichwere appreciably affected byplasmaturbidity. Oneofthe instruments wasunabletodetect aclotin a moderately turbidplasma. A second instrument gaveresults whichweresignificantly affected byturbidity. Turbidity ofthesubstrate plasmadidnotaffect specific factor VIIIassays intwotypesof coagulometer. Conclusions: Lyophilisation of plasma inducesturbidity duetotheagglomerationoflipids. Suchturbidity canaffect the results ofcoagulation tests. Suppliers of lyophilised plasmasshouldbe awareof thisproblem.

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