Pattern of thyroid hormones in mildly protein-deficient women in area endemic for goiter

This study refers to 23 nonpregnant and 5 pregnant Ethiopian women living in a severely iodine-deficient area exposed to marginal chronic protein malnutrition. About half the study group exhibited goiter. The components of retinol circulating complex have been measured: transthyretin, retinol, and retinol-binding protein were 31 +/- 8 mg/dl, 36 +/- 6 micrograms/dl, and 3.1 +/- 0.6 mg/dl, respectively. No differences in circulating thyroid hormone pattern were found among goitrous and nongoitrous subjects. In nonpregnant women, the circulating thyroid hormone pattern was characterized by a low total T4 (TT4, 53 ng/ml), whereas free T4 (FT4, 0.5 ng/dl) was below the lower level of the range. Thyroid-stimulating hormone and FT3 were in the normal range, and TT3 was at the upper level of the range. The pregnant women exhibited the expected increase in total thyroid hormones (TT3 3.0 ng/ml, TT4 96 ng/ml), whereas the free fractions were equal to those of the nonpregnant subjects (FT3 2.5 pg/ml, FT4 0.6 ng/dl). In the whole group, the T3-T4 ratio was 3.4 x 10(-2), i.e., twice the normal ratio. No antibodies against thyroid structures were detected. These results indicate that the circulating thyroid hormone pattern of these marginally malnourished women differs from that reported for subjects with pure protein-calorie malnutrition or exposed to chronic iodine deficiency only. The main difference is that, even in the presence of low TT4 and FT4, the hypophysis-thyroid axis has apparently remained unchanged. The normal levels of TT3 and FT3, may account for the normal thyroid-hypophysis feedback.