Plasma levels of beta-thromboglobulin and platelet factor 4 in relation to the venous platelet concentration.

The plasma levels of beta-thromboglobulin (beta-TG) and platelet factor 4 (PF-4) were determined in patients with various hematologic malignancies, and the results were related to simultaneously determined venous platelet counts. All studied patients were in a steady state. The plasma beta-TG concentrations were determined on 69 occasions and the values ranged from 0 to 82 ng/ml. In 33 instances, the venous platelet count was <25 x 10 (9/1) and in two thirds of these samples beta-TG was undedectable. The highest values for plasma beta-TG were found in patients with the highest venous platelet counts. A highly significant correlation (r=0.77, p <0.001) between the values for plasma beta-TG and venous platelet count was present. The plasma concentrations for PF-4 ranged from 0 to 50 ng/ml. Similarly, there was a highly significant relationship (r=0.78, p<0.001) between the values for PF-4 and venous platelet concentration. We conclude, if the plasma levels of beta-TG and PF-4 are used as markers of platelet activation in vivo, it is necessary to simultaneously consider the platelet concentration in the collected blood.