Clinical conditions requiring adjustment of thyroxine dose

Conditions in which an increased dose of thyroxine may be required:

• increased thyroxine clearance:
  • phenytoin
  • carbamazepine
  • rifampicin
    
    
• reduced intestinal absorption
  • ferrous sulphate
  • cholestyramine
  • aluminium hydroxide
    
    
• increased concentration of serum thyroxine binding globulin:
  • pregnancy
  • increased body mass (1)
    
    
• reduced thyroxine clearance:
  • aging

Reference:

• Wood J. (1994).Thyroxine therapy. NEJM, 331 (3), 174-80.