EFFECT OF FIBRINOGEN SUBSTITUTION IN AFIBRINOGENEMIA ON HEMORHEOLOGY AND PLATELET-FUNCTION

Fibrinogen substitution can correct bleeding in afibrinogenemia. We as sessed the effect of fibrinogen substitution in a patient lacking immu noreactive fibrinogen. Fibrinogen and thrombin time were not measurabl e before, but became detectable within 30 min after substitution, para llelled by an increase in ADP-induced platelet aggregation from <10% t o 32%. Platelet adhesion, measured by Stagnation Point Flow Adhesio- A ggregometry, was not detectable prior to substitution but attained nor mal values thereafter. Scanning electron microscopy of adhering platel ets revealed pseudopodia protrusion and spreading. Morphometry reveale d two populations of spread platelets one of which demonstrated inhibi ted spreading as compared to healthy controls. Immunoelectron microsco py revealed normal GPIIb/IIIa receptor expression, both before and aft er substitution. Dynamic and kinematic viscosity of plasma and whole b lood remained below the 99.9% confidence border of a healthy control g roup. In afibrinogenemia fibrinogen levels as low as 10% of normal con centration sufficed to normalize coagulation. platelet adhesion, and, partially, spreading.