Elevated serum thyroxine-binding globulin by X-chromosome transmission.

A kindred with a high prevalence of hereditary serum thyroxine-binding globulin (TBG) is described. Seventeen of th 29 members of the kindred have the increased TBG trait as demonstrated by a combination of increased serum total thyroxine (T4) and total triiodothyronine (T3) and decreased T3 resin uptake. In 12 of the 17, the anomaly was confirmed by measuring serum TBG activity as maximum binding capacity of T4. The pattern of increased TBG is consistent with X-linked inheritance. One of the affected members had proven thyrotoxicosis and two others were subjected to sub-total thyroidectomy.