The rapid and specific detection of fibrin monomers (fm) and fibrin degradation products (fdp) is of major importance in the laboratory diagnosis of disseminated intravascular coagulation, deep vein thrombosis or pulmonary embolism. Most methods in use are either time-consuming, needing special techniques, or insensitive and poorly specific. Some time ago, Watanabe and Tullis described a simple and rapid, semiquantitative test to detect fm and fdp in plasma, based on the finding that ristocetin in low concentrations (1.0-1.5 mg/ml) can specifically precipitate fm and fdp. To 0.4 ml ACD plasma, 0.1 ml ristocetin (2.5 mg/ml) is added and vortexed. The mixture is then incubated for 30 min at 20°C and centrifuged at 50xg for 5 min. The test is considered to be positive when fibrin-like strands or small or large pellets are observed on the bottom of the tube. More recently, Pfliegler et al. reported that ristomycin (AGGRISTIN), a structural analogue of ristocetin, can replace ristocetin in this test.Here we report on further results with the ristomycin (AGGRISTIN) precipitation test in 138 patients with various intravascular thrombotic events. The results of this test, performed on ACD plasma, were compared to the serum fdp values detected by immunoelectrophoresis (IEF) and by the haemagglutina-tion inhibition test (HIT). In all 30 cases with serum fdp above 30 ug/ml (HIT) or 28 pg/ml (IEF), the precipitation test was positive; at lower fdp concentrations, as detected by HIT or IEF, the test still was positive in 70 per cent of these thrombosis patients, suggesting a superior sensitivity. In 16 patients with elevated fibrinogen levels (but no evidence of thrombosis), the test was positive in only 3. No false positive results were detected in 16 healthy controls. Preliminary results show that the minor disadvantage of the test (blood collection on acid citrate dextrose) may readily be overcome by the in vitro adjustment of the pH of citrate plasma, commonly used for other haemostatic tests, to between 7.0 and 7.4.On the basis of our results we suggest that the AGGRISTIN (ristomycin) precipitation test is a simple, rapid and reliable method for the laboratory diagnosis of intravascular clotting.
Acid-Citrate-Dextrose
