PB0771 - Testosterone Replacement Therapy Does Not Alter Stored Platelet Hemostatic Capacity

Background: Critical shortages in the national blood supply have led to a re-evaluation of previously overlooked donor sources for blood products. As a part of that effort, red blood cells collected from therapeutic phlebotomy of donors on testosterone replacement therapy (TRT) have been conditionally approved for transfusion. However, platelets from TRT donors are not currently approved for use due to limited data on effects of supraphysiologic testosterone on recipient safety and platelet function.

Aims: To provide a comprehensive profile of phenotype and function in stored platelets isolated from TRT and control donors.

Methods: Platelets in plasma were collected from TRT and control donors (N=10 per group; age- and sex-matched) using the whole blood/platelet-rich plasma method and stored at room temperature for 7 days. On storage day 1 (D1) and 7 (D7), platelet products were analyzed for platelet count, surface receptor expression, aggregation, thrombin generation, and thrombus formation under physiological flow conditions. Total and free testosterone measurements were made in sera derived from whole blood samples taken from donors at time of donation.

Results: TRT donors had 3X the free testosterone in whole blood than control donors (Fig1). Yet, TRT donor platelets were not significantly different than control donor platelets in terms of count, surface phenotype, ability to aggregate, thrombin generation, or ability to form occlusive thrombus under arterial flow regimes (Fig2). After 7 days of room temperature storage, platelets from both groups had significantly lost hemostatic function compared to D1 counterparts; with no difference between control and TRT D7 platelets.

Conclusion(s): Platelets derived from donors undergoing TRT have similar phenotypic and functional profiles compared to those derived from control donors. This suggests that therapeutic phlebotomy of TRT donors may provide a useful source for platelet products, and that increased circulating free testosterone does not impact platelet function (assessed in vitro).