SERUM CONCENTRATIONS OF THYROXINE-BINDING GLOBULIN, PREALBUMIN AND ALBUMIN IN HEALTHY FULLTERM, SMALL-FOR-GESTATIONAL AGE AND PRETERM NEWBORN INFANTS

Abstract. Jacobsen, B. B., Peitersen, B., Andersen, H. J. and Hummer, L. (The University Clinic of Paediatrics, Children's Hospital Fuglebakken and the Departments of Nuclear Medicine, Rigshospitalet, Copenhagen, Denmark). Serum concentrations of thyroxine-binding globulin, prealbumin and albumin in healthy fullterm, small-for-gestational age and preterm newborn infants. Acta Paediatr Scand, 68: 49, 1979.—Simultaneous serum concentrations of thyroxine-binding globulin (TBG), prealbumin (TBPA) and albumin (Alb) were measured in 130 fullterm, 32 small-for-gestational age and 25 preterm infants during their first six days of life. In all infants serum concentrations of TBG were higher and serum TBPA and Alb were lower than in male adults. Even higher serum TBG levels wer found in the mothers. There was no correlation between serum concentrations in paired maternal and cord sera. In infants with birth weights appropriate for gestation serum TBG, TBPA, and Alb concentrations increased progressively with gestational age. In small-for-gestational age infants born at term serum concentrations of TBG and Alb were lower than those in full-term, but higher than those in premature newborns. Serum TBPA in small-for-gestational age babies was evne lower than seen in prematures. A positive correlation was found between thyroid hormones and TBG concentrations, not between serum TBPA and thyroid hormones. The ratios between serum concentration of thyroid hormones and proteins might indicate that more thyroid hormonebinding sites are occupied in fullterm than in low birth-weight newborns. However, the main reason for the different serum levels of thyroid hormones in fullterm, small-for-gestational age and preterm babies is probably the various serum TBG concentrations demonstrated in these infants.