Biokinetics and radiation dosimetry for patients undergoing a glycerol tri[1-14C]oleate fat malabsorption breath test

The glycerol tri[1-14C]olein test for fat malabsorption was carried out in two male volunteers and measurements of the loss of 14C in expired air, urine and faeces and the retention of 14C in biopsy samples of abdominal fat were made using accelerator mass spectrometry. Exhalation accounted for 73% and 55% of the administered activity and could be described by three-component exponential functions with halftimes of about 1 h, 2 days and 150 days, respectively. Urinary excretion accounted for 24% of the administered activity, almost all during the first 24 h after administration; about 2% was excreted in the faeces in 48 h. The halftime of retention of 14C in fat ranged from 137 to 620 days. Absorbed dose calculations indicate that for a normal adult the largest dose, 1.5–7.0 mGy/MBq is received by the adipose tissue, and that the effective dose is 0.3–0.5 mSv/MBq. It is concluded that no restrictions need to be placed on radiation safety grounds on the administration of 0.05–0.1 MBq 14C-triolein for the triolein breath test.