1974 Volume 112 Issue 1 Pages 35-46
In a family with X-chromosome-linked inheritance of thyroxine (T4)-binding globulin (TBG) deficiency, serum free T4 values were low in three of four members, but free triiodothyronine (T3) values were normal in all four of them. Binding capacities of T4-binding prealbumin (TBPA) were high in three of four members. In the propositus, a 47-year-old male, whose T4-binding capacity of TBG was null, half-time of serum T4 was shortened, turnover rate, distribution space and clearance rate all increased, extrathyroidal organic iodine pool decreased and degradation rate of T4 was unchanged compared with normal values. While half-time of his serum T3 was prolonged, turnover rate, extrathyroidal pool and degradation rate of T3 decreased, and T3 distribution space and clearance rate increased compared with normal values. When 0.24mg of ethinylestradiol-3-methylester was administered daily by mouth to the propositus for 1 month, halftime of serum T4 was prolonged, total T4 increased and T4-binding capacity of TBPA decreased but free T4, T4-binding capacity of TBG and the degradation rate of T4 were unchanged. Meanwhile half-time of his serum T3 was shortened, total and free T3 levels and degradation rate of T3 increased.
