Propranolol and thyroid hormone metabolism

Thyroid. Summer 1991;1(3):273-7. doi: 10.1089/thy.1991.1.273.


Propranolol decreases plasma T3 and increases plasma rT3 in a dose-dependent manner due to a decreased production rate of T3 and a decreased metabolic clearance rate of rT3, respectively, caused by inhibition of the conversion of T4 into T3 and of rT3 into 3,3'-T2. This inhibition of 5'-deiodination is not secondary to inhibition of thyroid hormone transport across the plasma membrane. Propranolol and its major metabolite, 4-hydroxypropranolol, are not directly responsible for these effects, but an unidentified metabolite of propranolol might be involved. beta-blockers ameliorate clinical symptoms and signs of thyrotoxicosis independent of the decrease of plasma 13, that is confined to beta-blockers with membrane-stabilizing activity, such as propranolol and alprenolol. The decrease of plasma T3, however, appears responsible for some of the metabolic responses to beta-blockers.

Publication types

  • Review

MeSH terms

  • Adrenergic beta-Antagonists / pharmacology
  • Humans
  • Hypothyroidism / drug therapy
  • Metabolic Clearance Rate
  • Propranolol / pharmacology*
  • Thyroid Gland / drug effects
  • Thyroid Gland / metabolism
  • Thyroid Hormones / metabolism*
  • Thyrotropin / blood
  • Thyroxine / blood
  • Triiodothyronine / blood


  • Adrenergic beta-Antagonists
  • Thyroid Hormones
  • Triiodothyronine
  • Thyrotropin
  • Propranolol
  • Thyroxine