Platelet function by afibrinogenemia.

Platelet function was studied in two cases with congenital afibrinogenemia. In these two cases there was no aggregation by ADP, while, there was increased calcium-induced platelet aggregation and decreased platelet adhesiveness to glass. Platelet aggregation was corrected in vitro, by addition of fibrinogen. It can be concluded from the above findings that the fibrinogen is an important factor for platelet aggregation by ADP and for platelet adhesion to glass surfaces, while platelet aggregation by thrombin does not need fibrinogen. The increased calcium-induced aggregation can be explained by postulating that thrombin finds no substrate to act upon except the platelets.