J Korean Pediatr Soc.  1980 Jan;23(1):1-14.

A Study of Serum T4, T3 RU, and T7 Levels in Korean Mother and ewborn Infant

• Nam SD

Abstract

Thyroid function in term fetus has mot been clearly defined. The direction and extent of net placental thyroid hormone transfer near term and the relative maternal and fetal contributions to total fetal thyroid hormone needs are not known clearly yet. Earlier reports of human T4 concentrations in maternal and cord blood have been conflicting : both maternal- fetal and fetal-maternal concentration gradients, and identical maternal and fetal concentration have been reported. The presented study was undertaken to clarify transplacental gradients of T4, T3, RU and free T4, at term using recently developed, sensitive methods for measurement of these parameters of thyroid function. Total T4, T3 RU and T7, concentration were studied in 20 pairs of maternal and umbilical cord blood samples collecting during vaginal deliveries. Following results were obtained. 1) Mean total thyroxine levels of maternal and cord blood were similar. (13.0 versus 13,3ug%, respectively, p>o.1) 2) Whereas, T3RU (17.3 and 28.1%, respectively, p<0.001) and T7 concentrations (2.2 and 3.75, respectively, p<0.001) were higher in cord blood samples. These data indicate that serum serum T3 RU and free T4 (T7) concentrations in the term fetus exceed maternal levels. 3) This fetus-maternal gradient of free T4 support that the concept of a fetal hypothalamic-pituitary-thyroid control system is functioning independently Furthermore, All of the thyroid hormone requited by the normal term fetus is probably derived from his own thyroidal secretion

MeSH Terms

Fetal Blood
Fetus
Humans
Infant*
Mothers*
Thyroid Gland
Thyroxine
Thyroxine