The effect of starvation and refeeding with oral versus intravenous glucose on serum 3,5-,3,3'-and 3'-5'-diiodothyronine and 3'-monoiodothyronine

Abstract

Abstract.: The effect of complete fasting on the serum concentrations of the iodothyronines 3,5-diiodothyronine (3,5-T 2), 3,3'-T 2, 3', 5'-T 2 and 3'-monoiodothyronine (3'-T 1) was evaluated. Fourteen obese women underwent a complete fasting for 4 days. Caloric restriction resulted in the following serum hormone levels (before vs 3. day): T 4: 103 vs 109 nmol/l (NS), T 3: 1.83 vs 1.24 nmol/1 (P < 0.01), rT 3: 0.276 vs 0.407 nmol/l (P < 0.01), 3.5-T 2: 70 vs 70 pmol/l (NS), 3.3'-T 2: 42 vs 39 pmol/l (P < 0.01), 3',5'-T 2: 63 vs 93 pmol/l (P < 0.01), and 3'-T 1 60 vs 116 pmol/l (P < 0.01). All subjects were refed with 200 g (800 kcal, 3350 kJ) d-glucose per day in divided doses for 2 days. Refeeding tended to normalize the changed iodothyronine concentrations and there was no difference whether the glucose was administered by the oral (n = 7) or the intravenous route. It can be concluded that starvation in man is accompanied by profound changes in peripheral metabolism of the T 2's and 3'-T 1. There seems to be no qualitative difference of the effect on the thyroid hormone metabolism of d-glucose administered by the oral or the intravenous route.