Hormones in 'young' and 'old' elderly: pituitary-thyroid and pituitary-adrenal axes.

Changes of the pituitary-thyroid and pituitary-adrenal hormone axes with age and possible differences between the sexes in the elderly were studied in 60-year-old (n = 39) and 80-year-old (n = 34) non-hospitalized subjects. The 80-year-old age group had a significantly lower response of thyrotropin (TSH) to thyrotropin-releasing hormone (TRH; p less than 0.05). Otherwise, there were no significant differences between the two age groups. Sex differences were found for plasma arginine vasopressin and cortisol excretion (higher values in men), and free thyroxine index, TSH and prolactin response to TRH (higher values in women). Cortisol levels after dexamethasone were negatively correlated to body mass index. There were no differences in hormone levels between smokers and non-smokers. In obtaining reference values for hormones in old age it is important to consider possible changes after the age of 60 years and to adjust for gender and body mass.