Splenic blood flow and intrasplenic platelet kinetics in relation to spleen volume.

The relationship between the splenic blood flow and the intrasplenic platelet kinetics on the one hand, i.e. the two factors which govern the size of the exchangeable splenic platelet pool, and the spleen size on the other were assessed in 21 patients afflicted with haematologic disorders and variable splenomegaly. The splenic blood flow and intrasplenic platelet kinetics were measured using 111In-labelled platelets and compartmental analysis of their equilibration between circulating blood and splenic pool; the spleen size was determined by scintigraphy using 99mTc-labelled stannous colloid. Significant correlations were recorded between the spleen size and the splenic platelet pool size (r = 0.76; P less than 0.001) and between the spleen size and the splenic blood flow (r = 0.56; P less than 0.01). Splenic perfusion decreased significantly with increasing spleen size, but there was no relationship between the spleen size and the intrasplenic platelet transit time. However, an association was present between splenic perfusion and intrasplenic platelet transit time (r = -0.44; P less than 0.05). It is concluded that the splenic blood flow is the major determinant of the size of the exchangeable splenic platelet pool in splenomegalic states, and that the determination of spleen size using 99mTc-scintigraphy gives a rough estimation of the pool size. Splenic perfusion appears to be one of the factors which determine the intrasplenic platelet transit time.