Radioimmunoassay for Serum Thyroxine-Binding Globulin: Results in Normal Subjects and in Patients with Hepatocellular Carcinoma

Abstract

Serum thyroxine-binding globulin (TBG) was measured by radioimmunoassay. The human TBG used in this study was purified by affinity, anion-exchange, and gel filtration chromatography. The serum TBG concentration in 98 euthyroid normals was 1.48 ± 0.46 mg/lOO ml (mean ± SD), which is one-half that previously reported using a similar method. The level in females (1.66 ± 0.56) was significantly higher than that in males (1.37 ± 0.37). Comparison of the serum TBG level and the maximum binding capacity of serum TBG for thyroxine (T₄) yielded a molar ratio of 1:1 for T₄ and TBG. The mean serum TBG in 19 patients with hepatocellular carcinoma was 2.10 ± 1.29 mg/100 ml; however, only 2 of these patients had serum TBG levels outside the normal range.