[Concentration levels of thyroxine binding globulin and thyroxine in the blood of euthyroid children. Reliability and diagnostic value of the T4/TBG quotiens--establishing reference values].

The most important transportprotein for thyroxine (T4) is the thyroxine-binding globulin (TBG). This protein and T4 were determined using the radioimmunoassay method in bloodserum of 443 euthyreotic children. The age-specific analysis showed high TBG and T4 concentrations in the postnatal phase, nearly constancy between 1. and 9. years with concentrations in the upper physiological range of adults, elevation of the values in the age of 10/11. years and definite attainment of the normal range for adults at 12/13. years. The importance of the T4/TBG quotient for thyroid gland diagnostics was discussed.