[Thyroxin binding globulin (TBG) radioimmunoassay. Normal patients results according to age, and sex, and in the cases of dysthyroidisms (author's transl)].

The value of TBG serum concentration for the exploration of thyroid function was studied by radioimmunoassay in 203 patients (133 normals, 62 dysthyroidism, 8 women taking oral contraceptives). The results of the normal patients show important and as of yet unexplained variations of TBG levels, depending on age and sex. In hyperthyroidism, serum TBG was reduced significantly in women and no significantly in men. In hypothyroidism, the levels are significantly high in both sexes. Like the TRH test, the TBG serum concentration determination may be helpful for the diagnosis of a slight hypothyroidism. Moreover, as the serum levels return to normal values with substitutive therapy, TBG assay may be used as a follow-up test during the treatment of hypothyroid patients.