Thyroid iodide clearance and radioiodide uptake in protein-calorie malnutrition

The thyroid function was evaluated in two comparable groups of 12 protein-calorie malnourished children respectively by oral and intravenous test using radioiodine 131I. Maximal radioiodide uptake (RAIUmax) peaked within 24 hr in the intravenously investigated children, but only after 48 hr in the orally investigated children. In both protein-calorie malnutrition groups, the mean RAIUmax was significantly decreased by comparison with the mean normal RAIUmax (P less than 0.01). In protein-calorie malnutrition children, the RAIU curve reached intermediate values ranging from subnormal to about nearly half the normal. Thyroid clearance was early depressed and in some cases, dropped to values as low as one tenth of the normal mean (P less than 0.001), reflecting a severe thyroid involution. There is a high correlation between the RAIUmax and thyroid clearance values (r = 0.95); the regression line is defined by the equation Y = 1.12X + 17.08. Both functional parameters of thyroid activity appear to be mainly lowered in relation to the duration of protein deficiency.