Quality control of technetium-99m DTPA: correlation of analytic tests with in vivo protein binding in man

When [99mTc]DTPA is administered, a small fraction of the activity (presumably an impurity) is bound to plasma proteins. This causes an error in the calculation of glomerular filtration rate from plasma clearance. This paper presents two methods of laboratory quality control for measuring the fraction that binds to plasma proteins. One method involves in vitro binding to human serum albumin followed by gel filtration. The other method involves descending paper chromatography on wet pre-equilibrated anion exchange paper. In a series of 80 patients, correlation was demonstrated between laboratory characteristics and actual clinical performance of the [99mTc]DTPA preparation. Both laboratory methods appear suitable for routine quality control.