Plasma Volume Determination by 99mTc-labeled Albumin and 125I-labeled Albumin

For many years, radioiodinated albumin has been "the golden standard" for measurement of plasma volume. There are a number of clinical situations in which a nuclide with a shorter half-life would be preferred. Furthermore, due to periodic lapses in the availability in the delivery of 125I-labeled albumin, there is a need to evaluate another nuclide as a tracer for plasma volume determination.

99mTc-labeled albumin is easily prepared by a simple and reproducible method with a high labeling efficiency and short half-life.

In this study, we want to compare plasma volume determined by 99mTc-labeled albumin with plasma volume determined by 125I-albumin (golden standard). In both procedures, plasma volume is estimated from multiple postinjection samples for accurate zero-time extrapolation in order to correct for leakage of labeled albumin from the vascular compartment.