[The determination of platelet factor 3 using hirudin].

The influence of blood platelets on the recalcification time under hirudin was investigated. Contrary to the investigations of whole-blood which reveal a pathological prolongation of the hirudin tolerance test only at platelet numbers under 30,000/mug, a change of the recalcification time under hirudin could also be found in the plasma at higher platelet numbers. The recalcification time increased inversely proportionally with falling platelet number. The shortening of time in platelets rich plasma attributed to the activity of platelet factor 3. Differences in the examinations of whole-blood may be attributed to an erythrocyte activity similar to factor 3. The application of hirudin for determining platelet factor 3 is recommended as a sensible method easily to be performed in practice.