Thyroid gland function of rats subjected to low-protein lipid-enriched diet

The reports on the thyroid gland function in protein nutitional deficiency are controversial. The aim of this study was to determine the effects of protein deficient diet upon the thyroid gland function of rats subjected to an isocaloric protein deficient diet (2.7 g%) containing an excess of fat as protein substitute (31.0 g%), being the standard diet composition, protein 27.6 g% and fat 14.6 g%. ¹³¹I uptake by the thyroid gland was decreased (0.19% in relation to 0.26%); T/S ratio was reduced (4.92, control 57.66); PB¹³¹I/¹³¹I ratio was diminished, 0.28 to 0.17. T₄ plasma level was unchanged, but T₃ was increased (328.22 ng/100 ml, control, 71.83 ng/100 ml). There was a non significant reduction on TSH plasma level (6.97 μU/ml, control 7.57 μU/ml). The results could be interpreted as a decrease in thyroid gland function secondary to a complex situation produced by the low-protein lipid-enriched diet.