Endocrine Abstracts

Introduction: Aging is associated with a decrease in muscle and bone mass, and a gain in fat mass. Similar changes are more pronounced in hypercortisolism. We previously demonstrated that high 8 PM salivary cortisol is independently associated with increased prevalence of radiologic vertebral fractures. We wanted to determine whether salivary cortisol circadian rhythm played also a role on body composition.

Material and Methods: Cross-sectional study including 538 women >50 years old (mean age 63.6±7.5) from the OsteoLaus cohort. Included participants had: body composition assessment by DXA, salivary cortisol circadian rhythm measures (awakening, 30 minutes thereafter, 11 AM and 8 PM) and assessment of handgrip. On top of body composition parameters, sarcopenia prevalence, as defined by the EWGSOP group (appendicular lean mass by height squared (ALMI) < 5.5 kg/m² and muscle strength < 20 kg), was analyzed.

Results: Salivary cortisol at 11 AM and 8 PM increased with age. We found no association between salivary cortisol circadian rhythm values and fat distribution (total fat, fat mass index, or visceral fat). Neither total lean mass, nor ALMI were separately associated with salivary cortisol measures. There were 15 sarcopenic participants that were older (67.5±7.5 vs. 63.4±7.5 yo) and had lower BMI (20.4±2.8 vs. 26.2±4.6 kg/m²). Sarcopenia presence was positively associated to 11 AM and 8 PM values in monovariate analysis and after adjustment to age and BMI (adjusted p-values 0.021 and 0.044, respectively). Sarcopenic participants had significantly higher values of salivary cortisol than not sarcopenic participants at 11 AM (13.1±6.5 vs. 9.2±4.5 mmol/l) and 8 PM (5.1±5.1 vs. 3.3±2.1 mmol).

Conclusions: Salivary cortisol values are not associated to fat neither lean mass distribution as assessed by DXA. However, highest values at nadir time points 11 AM and 8 PM are associated to sarcopenia prevalence as defined by the EWGSOP group, independently of age and BMI. If these results are confirmed in other studies, the measurement of salivary cortisol at 8 PM may play a role in the assessment of sarcopenia.