Rate of clearance by the spleen of heat-damaged erythrocytes.

The rate of uptake in the spleen of heat-damaged red blood cells labelled with 99mTc has been measured by radioisotope scanning in 38 patients. The values obtained for the half-clearance time into the spleen using this method have been compared with the values obtained simultaneously by blood sampling for the rate of loss of radioactivity from the circulation. It was found that the uptake into the spleen was approximately three times faster than the measured rate of loss of radioactivity from the blood. The reasons for this are discussed and it is suggested that the scanning technique is more reliable as a measure of this aspect of splenic function.