Changes in sleeping and basal energy expenditure and substrate oxidation induced by short term thyroxin administration in man

Obes Res. 1996 May;4(3):213-9. doi: 10.1002/j.1550-8528.1996.tb00539.x.


The present study was designed to explore the thermogenic effect of thyroid hormone administration and the resulting changes in nitrogen homeostasis. Normal male volunteers (n = 7) received thyroxin during 6 weeks. The first 3-week period served to suppress endogenous thyroid secretion (180 micrograms T4/day). This dose was doubled for the next 3 weeks. Sleeping energy expenditure (respiratory chamber) and BMR (hood) were measured by indirect calorimetry, under standardized conditions. Sleeping heart rate was continuously recorded and urine was collected during this 12-hour period to assess nitrogen excretion. The changes in energy expenditure, heart rate and nitrogen balance were then related to the excess thyroxin administered. After 3 weeks of treatment, serum TSH level fell to 0.15 mU/L, indicating an almost complete inhibition of the pituitary-thyroid axis. During this phase of treatment there was an increase in sleeping EE and sleeping heart rate, which increased further by doubling the T4 dose (delta EE: +8.5 +/- 2.3%, delta heart rate +16.1 +/- 2.2%). The T4 dose, which is currently used as a substitutive dose, lead to a borderline hyperthyroid state, with an increase in EE and heart rate. Exogenous T4 administration provoked a significant increase in urinary nitrogen excretion averaging 40%. It is concluded that T4 provokes an important stimulation of EE, which is mostly mediated by an excess protein oxidation.

Publication types

  • Clinical Trial

MeSH terms

  • Adult
  • Body Composition / physiology
  • Calorimetry, Indirect
  • Carbohydrate Metabolism
  • Dose-Response Relationship, Drug
  • Energy Metabolism / drug effects*
  • Energy Metabolism / physiology
  • Heart Rate / drug effects
  • Heart Rate / physiology
  • Homeostasis / drug effects
  • Homeostasis / physiology
  • Humans
  • Hypothalamo-Hypophyseal System / drug effects
  • Hypothalamo-Hypophyseal System / physiology
  • Lipid Metabolism
  • Male
  • Nitrogen / metabolism
  • Nitrogen / urine
  • Oxidation-Reduction
  • Sleep / drug effects*
  • Sleep / physiology
  • Thyroid Gland / drug effects
  • Thyroid Gland / physiology
  • Thyrotropin / blood
  • Thyroxine / administration & dosage
  • Thyroxine / blood
  • Thyroxine / pharmacology*
  • Time Factors
  • Triiodothyronine / blood


  • Triiodothyronine
  • Thyrotropin
  • Nitrogen
  • Thyroxine