Plasma triiodothyronine response to thyrotropin releasing hormone, thyrotropin and propranolol in old age

I. Szabolcs, G. Szilágyi, M. Góth, Zs Kovács, M. Weber, T. Halász

Research output: Contribution to journalArticle

7 Citations (Scopus)


The blood T3 levels were lower and the rT3 levels higher in 70-90-year-old healthy subjects than in 20-40-year-old people. Similar T4 and T3 elevations could be seen after exogenous and endogenous (TRH induced) TSH stimulus in both groups. The pituitary TSH content in old age was sooner exhausted by repeated oral TRH administration. A persistent T3 elevation after endogenous TSH stimulus could be detected only in the control group, probably as a sign of peripheral T3 generation. Even small quantities of T3 significantly suppressed the TRH-induced TSH response in the old age group investigated. Propranolol, at the dosage used, inhibited T4-T3 conversion only in the old subjects, while the rT3 increased in both groups. These findings suggest that a more pronounced inhibitory effect of T3 on the pituitary TSH release is responsible for the decrease of TSH secretion and consecutive diminution of T3 secretion from the thyroid in old age. The peripheral generation of T3 seems to be inhibited too, probably by the elevated rT3 levels.

Original languageEnglish
Pages (from-to)309-316
Number of pages8
JournalExperimental gerontology
Issue number4
Publication statusPublished - 1981


ASJC Scopus subject areas

  • Biochemistry
  • Ageing
  • Molecular Biology
  • Genetics
  • Endocrinology
  • Cell Biology

Cite this