THROMBIN TREATED PLASMA EMPLOYED AS A STANDARD FOR DETERMINATION OF SOLUBLE FIBRIN

The Coa-set Fibrin Monomer test (CFM-test) is a quantitative method fo r determination of soluble fibrin in plasma. The fibrin standard of th e CFM-test is produced by bathroxobin conversion of purified fibrinoge n to fibrin. Plasma treated with minute amounts of thrombin may be con sidered as a more physiological way of preparing fibrin monomers. Ther efore, we have employed such thrombin treated plasma (TTP) as an alter native fibrin standard for the CFM-test. The fibrin concentration of t he TTP was determined indirectly by quantitation of released fibrinope ptide A. The TTP was stable during freezing, thawing and storage for 3 months at -70 degrees C. The standard curve obtained using TTP as a s tandard was linear in the range of 0 - 275 nmol/l fibrin in plasma, bu t the slope of the line was less steep than the original standard curv e. This difference was probably due to the greater plasminogen activat ing effect of bathroxobin digested fibrinogen compared to soluble fibr in generated in plasma by thrombin, as observed in a previous study. B ecause of the less steep slope of the alternative standard curve, fibr in levels in plasma samples from 20 healthy volunteers and 25 patients were found to be higher employing TTP as a standard. Preparation of a fibrin standard by incubation of plasma with minute amounts of thromb in will to some extent mimic the process of fibrin generation in vivo. Since we have found a satisfactory stability of such a standard durin g freezing, thawing and storage, we think the TTP standard might be us eful for quantitation of soluble fibrin in plasma.