Summary
The pathogenesis of thrombocytopenia induced by intravenous protamine sulphate was
studied in six patients who underwent cardiopulmonary bypass surgery, and in three
normal volunteers. Autologous platelets were labelled with 111Indium-oxine. Platelet lifespan was determined. In vivo 111In-platelet localization, organ redistribution and sites of destruction were quantitated
with a scintillation camera and a computer-assisted imaging system. Protamine induced
a transient thrombocytopenia, maximal 5-10 min after injection, and 30-40 min in duration.
The thrombocytopenia was accompanied by a transient accumulation of platelets in the
liver. The splenic platelet pool remained unaltered and no platelets accumulated in
the lungs. Platelet survival, measured in two volunteers, was slightly longer than
normal and fitted a linear function best. There was a severe transient neutropenia
during the period of thrombocytopenia. We conclude that protamineinduced thrombocytopenia
is caused by hepatic accumulation of "activated" platelets or platelet aggregates,
the process is reversible, and in the two normal volunteers studied, platelet survival
was not affected.
Key words
Platelet kinetics -
111Indium-oxine labelled human platelets - Protamine sulphate - Thrombocytopenia, protamine
induced - Neutropenia, protamine induced