MEASUREMENT OF GLOMERULAR FILTRATION RATE USING CHELATED YTTERBIUM-169

Ytterbium-169 chelated with diethylenetriaminepentaacetic acid (169Yb-DTPA) was developed and evaluated for possible use as a glomerular substance. The radionuclide has a high photon yield with complex gamma ray spectrum. It has a physical half-life of 32 days, but less than 1 percent of intravenously injected chelated complex is retained in the body, which limits the radiation exposure. Gel fitration studies showed that 169Yb-DTPA complex did not bind to plasma proteins and was excreted unchanged in the urine. The clearance rate of the complex was found to be independent of the plasma concentrations of Yb-DTPA. The renal clearance of 169Yb-DTPA was compared simultaneously with that of 14C-inulin in dogs, normal human subjects and patients with renal disease. Nearly identical results were obtained with both the agents over a wide range of glomerular filteration rate. The radiation doses due to different glomerular agents containing 131I, 125I, 57Co, 99mTc, 51Cr, 113mIn, 140La and 169Yb were calculated for normal and impaired renal conditions, 169Yb-DTPA was found to deliver comparatively low radiation doses. It was believed to be a safe, inexpensive and effective new agent for the measurement of glomerular filtration rate. © 1969.