Background and methods: Twenty-five thrombocytopenic patients underwent quantitative in vivo platelet kinetic studies using a scintillation camera and a computer-assisted imaging system. They fulfilled the criteria for chronic immune thrombocytopenia, and the object of the study was to evaluate platelet sequestration and destruction in the spleen. In this sense, the differences in the distribution of the radiolabelled platelets in the spleen and the liver, as well as the differences in the platelet mean life span (MLS) as computed by different methods were assessed. Serial images of the spleen pool, liver and heart were taken after reinjection of In-111-oxine labelled autologous platelets.
Results and conclusions: The spleen/liver ratio proved to be a more reliable index in indicating the splenectomy outcome that the Z index (see text). Platelet survival curves were analyzed using four mathematical models, and it was found that MLS estimation is model dependent. Thus, it seem advisable to apply at least two different methods when analyzing experimental data.