The use of technetium-99m labelled heat-damaged red cells for the quantitative measurement of splenic function.

A comparison of the rates of clearance of 51Cr labelled and 99mTc labelled heat-damaged red cells in 25 patients and 4 control subjects is reported. Very little correlation was found between the clearance half-times of the two types of labelled cells when the cells were labelled with 99mTc prior to heat damaging. The correlation was improved when the labelling step occurred after the cells had been damaged. Urinary excretion measurements revealed that the rate of excretion of 99mTc could be as much as nine times that of the 51Cr label. 99mTc labelled heat-damaged red cells were found not to be sufficiently stable a preparation for use in quantitative clearance studies.