Cortisol levels and metabolic parameters in middle- and advanced- age subjects: associations with age

BACKGROUND

It has been reported that morning cortisol levels increase with age, although there is some controversy in the literature.

AIM

The aim of this study was to examine associations of cortisol levels with advancing age in an elderly population and investigate possible interactions with metabolic and hormonal parameters.

SUBJECTS AND METHODS

From 372 subjects initially evaluated, we studied 251 ambulatory subjects aged 51-90 yr, median 71 yr (169 women), all permanent residents of a small town in southern Greece. Anthropometric parameters, glucose, insulin, cortisol, and biochemical parameters were recorded.

RESULTS

Fasting cortisol levels (08:00-09:00 h) varied between 150.9- 854 nmol/l (mean 362.4 nmol/l). A significant association was found between age and cortisol levels (Spearman's rho =0.170, p=0.01). There was a positive correlation between cortisol levels and creatinine (Spearman's rho =0.144, p=0.023), homocysteine (Spearman's rho =0.283, p<0.001) and a negative correlation with body mass index (Spearman's rho =-0.128, p=0.047). Multivariate analysis showed that when creatinine was taken into account, the association of cortisol with age and with homocysteine was no longer significant. When, however, diabetic subjects were included in the analysis, the adjusted for creatinine association of cortisol with age was significant (β=0.168, p<0.05).

CONCLUSIONS

It is concluded that, in elderly ambulatory subjects, the reported associations between cortisol levels, age, and homocysteine may be affected by coexisting co-morbidities or possibly by a decline in renal function. In subsequent studies it is important that fasting glycemia is taken into account.

Lower early morning plasma cortisol levels are associated with thyroid autoimmunity in the elderly

OBJECTIVES

Thyroid autoimmunity decreases in the very old. We investigated whether glucocorticoid (GC) activity, which increases in old age, is involved in this process.

SUBJECTS AND METHODS

A total of 321 ambulatory subjects (age 51-95 years, median 71, 207 female) were studied. Thyroid function tests, cortisol, glucose, insulin and biochemical parameters were measured. A modified overnight dexamethasone suppression test (0.25 mg) was performed as an index of GC sensitivity.

RESULTS

Forty subjects had positive anti-thyroid peroxidase antibodies and 36 had positive anti-thyroglobulin antibodies, while 57 had either one or the other or both thyroid autoantibodies (ThAbs) positive. Mean basal cortisol levels were significantly lower in the ThAbs (+) groups (320+/-125 vs 378+/-128 nmol/l, P=0.002). Triiodothyronine, free thyroxine, post-dexamethasone cortisol levels, C-reactive protein, homeostasis model assessment-insulin-resistance-index and body mass index did not differ between these two groups. Mean age of ThAbs (+) subjects was lower compared to the ThAbs (-) group (67.38+/-7.38 vs 71.64+/-8.57 years, P=0.001).

CONCLUSIONS

Reduced GC activity is associated with an increased prevalence of ThAbs positivity in older ambulatory subjects. Subjects without ThAbs in this population sample are relatively older. It is not known whether this is related to increasing GC activity with age.