[Reference values for blood levels of free thyroxine, free triiodothyronine and thyroxine-binding globulins in euthyroid children. Method: luminescence-enhanced enzyme immunoassay].

Concentrations of free thyroxine (n = 296, male 164, female = 132), free triiodothyronine (n = 273, male 156, female = 117) and thyroxine-binding globulin (n = 273, male 156, female = 117) were determined using the luminescence enhanced enzyme immunoassay method in blood-serum of euthyroid children. Beyond the 30, day of life no significant differences were found in different age groups for the free thyroxine and beyond the 2, day of life for the free triiodothyronine concentration. The free thyroxine values of the infants in the range of 15-39 pg/ml decreased to the range of 9-18.5 pg/ml and the free triiodothyronine values decreased from 3.4-9.3 pg/ml to the range of 2.8-6.5 pg/ml. The values for thyroxine-binding globulin increased in the first month of life up to the range of 18-35 mg/l and decreased afterwards continuously to the range of 14.5-26.5 mg/l.