Thyroid function in the newborn child

Assessment is made of the thyroid parameters in the early neonatal period against the background of age-related physiological peculiarities of the thyroid function. One hundred infants, born in the Institute of Obstetrics and Gynecology over the period 25th to 42nd gestation week, are studied. The umbilical cord serum levels of thyroxine, triiodothyronine and thyroiy-stimulating (TSH) levels are measured by a radioimmunologic method. The values of thyroxine disclose a steady increase with the progress of the gestation age of the fetus, and at childbirth they are higher than in adults. Triiodothyronine is lowered in all instances, and only in full-term infants it augments to reach the lowermost limit of the norm for adults. Reverse triiodothyronine is strongly elevated in all neonates, rather marked in premature infants. TSH exhibits no dependence whatsoever on the gestation age of the fetus, and at childbirth it is slightly above the uppermost limit of the norm for adults. Being aware of the peculiarities outlined has an essenti;l practical bearing on the correct interpretation of the results of ho of the results of hormonal studies, which in turn is closely linked to the problem of early detection and treatment of congenital hypothyroidism. (author)