The functional state of the thyroid system of children exposed in utero as a result of the Chernobyl disaster

A cohort of children exposed in utero after the Chernobyl accident is formed (n=422). Individual absorbed dose (AD) for the fetal thyroid was estimated from direct measurements of dose power for the maternal thyroid and was 0.01-4.5 Gy. The mean AD for the thyroid of pregnant women was 24.09+1.17 sGy, that of prenatally exposed children 44.74+2.58 sGy. Thyroid status of 195 exposed children and 220 controls is examined. Thyroid hormones were radioimmunoassayed and measured by enzyme immunoassay using standard diagnostic kits. Serum triiodothyronine concentrations were significantly increased in prenatally exposed children of both sexes (p<0.05 for boys and p<0.01 for girls). Serum thyroxin and thyroxin-binding globulin (TBG) levels were decreased in exposed boys in comparison with the control (p<0.05). In exposed girls thyroxin levels were virtually normal, but there was a tendency to an increase of thyroglobulin (t=1.6) and to a decrease of TBG (t= 1.7) in comparison with the control. The mean TBG concentration in the serum was below the norm in both groups. The results can be indicative of thyroid dysfunction in remote periods after prenatal exposure to radioactive iodine.