Yttrium chelate excretion studies have been conducted in this laboratory stimulated by the interest in the removal of fission products from man. Since diethylenetriaminepentaacetic acid (DTPA) has a high affinity for yttrium and is almost quantitatively excreted in 24 hr, the effectiveness of DTPA in removing yttrium from the body was studied in eight paticnts. Yttrium was injected intravenously as the nitrilotriacetate (YQo-NTA), a weak chelate, and 24 hr later, 500 mg DTPA was infused daily on four successive days. The YgO excretion was then compared with the results obtained with equivalent amounts of EDTA.The effectiveness of 2 g of either chelate was also studied. The infusions of 500 mg DL'PA increased the yttrium excretion from four to eight times over the base line excretion. DTPA was more effective than EDTA and a fourfold increase of either chelate did not result in an appreciably higher excretion of the metal chelate than was achieved with the 500 mg dose. In studies carried out in two patients, doses of 100 mg DTPA were found to be less effective than 500 mg of this chelating agent. Similar studies of the removal of La140 indicate that DTPA is also more effective than EDTA in removing this rare earth isotope from man. The significance of these decontamination studies and their possible application for fission product -removal will be discussed.

No abstract