[The appropriate use of clinical biological tests in hypercoagulability]. / Du bon usage de la biologie clinique en matière d'hypercoagulabilité.

Biological markers who are associated with hypercoagulability are of two types: Markers of activation: among them, the most interesting are the D-dimers which are good tools of diagnostic for the deep venous thrombosis and the pulmonary embolism. Thanks to their high negative predictive value. Etiological factors of hypercoagulable states and thrombosis, in other words: the "hypercoagulability chek up". This one should never be systematic. We propose either to practice it one month after the end of the anticoagulant therapy or to make it with prophylactic doses of low molecular weight heparin and far from the thrombotic episode.

Latex agglutination assay of human immunoglobulin M antitoxoplasma antibodies which uses enzymatically treated antigen-coated particles.

An assay of immunoglobulin M (IgM) antitoxoplasma antibodies which is rapid (less than 30 min), homogeneous, and reliable (interassay coefficient of variation, less than 11%) is proposed. Its principle is based on the observation that a suspension of latex particles coated with toxoplasma antigens, after treatment with proteinase K, becomes less agglutinable by IgG antibodies but more agglutinable by IgM antibodies. The difference between the activities of the two classes of antibodies is increased by the addition of a monoclonal antibody directed against the Fc region of IgM. Agglutination is measured with a special instrument which optically counts the particles that remain free after the reaction. Turbidimetric reading, although less sensitive, is also suitable. No significant interferences either by IgG antitoxoplasma antibodies or by rheumatoid factor or antinuclear antibodies were observed. The sensitivity was similar to that of the immunosorbent agglutination assay.

Immunoassay by particle counting for coagulation testing: application to the determination of antithrombin III, von Willebrand factor antigen (vWF:Ag) and plasminogen.

Based on immunoassay by particle counting, three methods for antithrombin III, von Willebrand factor and plasminogen were developed on an automated IMPACT machine and on a semi-automated MULTIPACT system. Precision of the techniques, measured at low, medium and high level of the calibration curve showed coefficients of variation varying from 4.3 to 13.8%. Accuracy was evaluated by dilution recovery test and by correlation with rocket immunoelectrophoresis and chromogenic substrate techniques. The results show that the proposed methods correlate well with existing techniques and that immunoassay by particle counting is applicable to several coagulation tests.

Diagnostic value of antithrombin III and aminopyrine breath test in liver disease.

To assess the value of the aminopyrine breath test (ABT) and antithrombin III (AT III) determinations in liver disease, both tests were performed on 77 consecutive patients who underwent liver biopsies for increased values of liver enzymes and in 20 patients with clinical cirrhosis. The mean values of AT III and ABT were significantly lower in cases of liver cirrhosis than in cases of steatosis and steatofibrosis. The AT III and ABT values were abnormal in, respectively, 83.9% (26/31) and 90.3% (28/31) of the patients with cirrhosis and 22.7% (15/66) and 28.8% (19/66) of the patients without cirrhosis. The association of the two tests increased the specificity without modifying the sensitivity. Both the AT III test and the ABT can be used as noninvasive diagnostic procedures for cirrhosis in patients for whom the liver biopsy is not available or contraindicated.

Antithrombin III, plasminogen and alpha 2 antiplasmin in jaundice. Clinical usefulness and prognostic significance.

In this prospective study, antithrombin III, plasminogen and alpha 2 antiplasmin which are synthetised by the liver were measured and compared with the Normotest, Thrombotest and fibrinogen concentrations in 92 consecutive jaundiced patients. Antithrombin III appeared to be the most discriminant coagulation test in differentiating hepatocellular from cholestatic jaundice. A high correlation was observed between antithrombin III, plasminogen and alpha 2 antiplasmin values suggesting that the liver synthesis of these parameters was closely linked. The prognostic significance of the blood coagulation tests in patients with jaundice has been studied. In parenchymatous liver disease, antithrombin III, plasminogen and alpha 2 antiplasmin were superior to the Normotest, Thrombotest and fibrinogen concentrations in predicting the prognosis of the patients at the time of admission. In cholestatic jaundice, however, none of the blood coagulation tests studied had a prognostic significance.

Evolution of antithrombin III during the postoperative period.

In a prospective study, antithrombin III (AT III) was performed preoperatively, peroperatively immediately after the surgical procedure and daily during the 8 postoperative days in 57 consecutive patients who underwent major abdominal surgery without prophylactic anticoagulant therapy. On d 8, according to the results of a bilateral radiological phlebography, the patients were divided into 2 groups: Group I: presence of deep venous thrombosis (DVT): n = 28 (49%) and Group 2: absence of deep venous thrombosis: n = 29 (52%). The results of the study showed that the preoperative AT III value did not constitute a marker of the postoperative DVT risk. During the postoperative period, AT III level decreased immediately following the intervention and resumed its preoperative value within 8 d. Nevertheless, this evolution was not different in the 2 groups and was not related to the presence of postoperative DVT.

The transfer test: a new screening procedure for thrombotic diseases.

The transfer test (TT) measures by means of thromboelastography the capacity of a plasma to shorten the coagulation time of a control plasma. The value of the TT was compared to that of fibrin(ogen), degradation products (FDP), and ethanol gelatin test (EGT) in various diseases (group I), in confirmed deep venous thrombosis (group II), and in confirmed pulmonary embolism (group III). In 211 consecutive patients admitted for various diseases the results of the TT, FDP, and EGT were abnormal in 12.3, 11.3, and 66.6%, respectively, of the cases. In 59 consecutive patients with deep venous thrombosis confirmed by radiological phlebography the results of TT, FDP, and EGT were abnormal at admission time in 96.6, 89.8, and 44%, respectively, of the cases. In 45 consecutive patients with pulmonary embolism confirmed by lung scintigraphy the results of TT, FDP, and EGT were abnormal at admission time in 97.7, 97.6, and 88%, respectively, of the cases. Among the three parameters which were evaluated, the TT seems to be the most sensitive screening procedure for thrombotic diseases. A normal result of TT is a strong argument against a recent thrombotic venous phenomenon.