[Oral load test with beta-carotene in normal and dysthyroid subjects]

An oral load of beta-carotene (500 mg) was administered to four normal, four hypo and four hyperthyroid subjects. Plasma beta-carotene content was determined at the 2nd, 4th, 6th, 8th, 10th, 12th and 24th hour after administration and at every 24th hour thereafter for 5 consecutive days. Plasma assays were performed by HPLC. No significant differences were revealed by Student's T test for one group to the other. The authors sustain that, as there is no impairment in intestinal uptake of beta-carotene in disthyroid subjects, the elsewhere described increase in carotinemia in hypothyroids is due to other mechanisms.