[Collection, preparation and storage of human plasma for radioimmunologic determination of thromboxane B2].

There are at present several methods available for the quantitative determination of thromboxane B2. However, they give results differing in precision and biological information. If it were possible to exclude sampling and storage artefacts, radioimmunological plasma thromboxane B2 measurement would be the method of choice for routine clinical determinations. The optimum conditions for processing the plasma for such purposes were assessed in 10 healthy volunteers (6m, 4f, 24-37a). They include a 30-minute resting period before blood sampling, constant needle diameter, blood withdrawal without venous occlusion, proper anticoagulation and cyclooxygenase inhibition. Storage at -70 degrees C for less than 2 weeks and the avoidance of repeated freezing and thawing are further prerequisites. In contrast to widely-held opinion, the plasma levels of thromboxane B2 obtained using these precautions are of practical value, roughly comparable to those employing the platelet proteins beta-thromboglobulin and platelet factor 4. However, practically speaking determinations are limited to a small number of carefully handled samples. Hence, the method cannot be unreservedly applied to daily routine clinical use.