The Effect of L-DOPA Administration on Thyrotropin (TSH) and Thyrotropin Releasing Hormone (TRH) Levels in Serum in Primary or Pituitary Hypothyroidism

Abstract

The effect of acute administration of L-DOPA on TSH and TRH levels in serum was studied in primary or pituitary hypothyroidism. TRH levels in serum fell and then returned to initial levels after L-DOPA administration in primary or pituitary hypothyroidism. TSH levels in serum fell and then returned. to initial levels after L-DOPA administration in primary hypothyroidism. T₄ and T3 levels in serum did not change after L-DOPA administration in primary or pituitary hypothyroidism. These data suggested that L-DOPA might act directly to hypothalamus.