Effects of norethandrolone on the transport in serum and peripheral turnover of thyroxine.

Abstract

The effects of the androgenicanabolic steroid, norethandrolone, on the binding of thyroxine (T4) in serum and on its peripheral metabolism in vivo have been studied in a total of 19 patients. In doses of 40 or 50 mg daily, norethandrolone decreased the T4-binding capacity of the thyroxine-binding globulin (TBG) and increased the binding capacity of the thyroxinebinding prealbumin (TBPA). The latter change was observed even when control values of the T4-binding capacity of TBPA were subnormal. Values for the serum PBI were also decreased by this agent. In 11 patients, norethandrolone increased the fractional rate of peripheral turnover of T4 and T4 clearance rate, but, because of the decrease in PBI, total daily T4 disposal was not significantly changed.