Effect of oral glucose feeding on thyroid hormone action in human mononuclear blood cells

The effect of glucose feeding on serum concentrations of thyroid hormones, nuclear T3 binding and thyroid hormone stimulated oxygen consumption and glucose uptake was evaluated. Six persons without thyroid diseases were fed exclusively glucose (2500 kcal/day) for two days. Glucose feeding resulted in the following serum hormone levels (before vs after glucose feeding) T3: 1.07 vs 1.16 nmol/l (p less than 0.05); FT4I: 76 vs 102 a.u. (p less than 0.05) and TSH: 1.48 vs 1.14 mU/l (n.s.). Nuclear T3 binding decreased after glucose feeding; before: maximal binding capacity (MBC) 1.3 +/- 0.5 fmol/100 ug DNA, MBC after glucose feeding: 0.8 +/- 0.2 fmol/100 ug DNA (p less than 0.05). The Ka's were identical in both groups before glucose, Ka: 4.2 +/- 1.2 x 10A10 l/mol, after glucose, Ka: 3.5 +/- 1.2 x 10(10) l/mol. Conversely did glucose feeding increase thyroid hormone stimulated oxygen consumption by approximately 100% and thyroid hormone stimulated glucose uptake by approximately 200%. In conclusion, our results show that glucose feeding 1) increases serum T3 levels, 2) decreases nuclear T3 binding, 3) enhances thyroid hormone stimulated oxygen consumption and glucose uptake.