Cortisol Production Rate and the Urinary Excretion of 17-Hydroxycorticosteroids, Free Cortisol, and 6β-Hydroxycortisol in Healthy Elderly Men and Women

BACKGROUND: Although many workers have tested adrenal function in the elderly, few have studied the effect of aging on cortisol production rate or urinary free cortisol or 6 beta-hydroxycortisol excretion, and none have published comparisons of these variables between old people of defined health status and young people. METHODS: We have measured cortisol production rate and the urinary excretion of free cortisol, 6 beta-hydroxycortisol, 17-hydroxycorticosteroids (Porter-Silber chromogens) and creatinine in elderly men and women screened by the SENIEUR protocol and in young men; 17-hydroxycorticosteroid and 6 beta-hydroxycortisol excretion were also measured in young women. The period of measurement was 24 h or, usually, 48 h. RESULTS: Only 6 beta-hydroxycortisol excretion was affected by aging; it was lower in the elderly men and women than in their younger counterparts. Urinary free cortisol excretion was lower in the elderly women than in the elderly men. There were no significant differences between groups in cortisol production rate or 17-hydroxycorticosteroid excretion. Excretion and (over the first 24 h) clearance of creatinine were lower in the old women than in the old men. The cortisol-related variables tended to be positively correlated with each other and with the relevant creatinine-related variables in the elderly subjects; over the first but not the second 24 h, most of the correlations were significant in the men and women combined. CONCLUSIONS: With the exception of 6 beta-hydroxycortisol, the data agree with measurements of plasma cortisol and the results of adrenal function tests in showing little change in hypothalamic-pituitary-adrenal function with aging in healthy people.