Summary
Fibrinogen substitution can correct bleeding in afibrinogenemia. We assessed the effect
of fibrinogen substitution in a patient lacking immunoreactive fibrinogen. Fibrinogen
and thrombin time were not measurable before, but became detectable within 30 min
after substitution, parallelled by an increase in ADP-induced platelet aggregation
from <10% to 32%. Platelet adhesion, measured by Stagnation Point Flow Adhesio- Aggregometry,
was notdetectable prior to substitution but attained normal values thereafter. Scanning
electron microscopy of adhering platelets revealed pseudopodia protrusion and spreading.
Morphometry revealed two populations of spread platelets one of which demonstrated
inhibited spreading as compared to healthy controls. Immunoelectron microscopy revealed
normal GPIIb/IIIa receptor expression, both before and after substitution. Dynamic
and kinematic viscosity of plasma and whole blood remained below the 99.9% confidence
border of a healthy control group. In afibrinogenemia fibrinogen levels as low as
10% of normal concentration sufficed to normalize coagulation, platelet adhesion,
and, partially, spreading.