Endocrinology of Aging From a Muscle Function Point of View: Results From the Toledo Study for Healthy Aging

Abstract

Introduction: Aging is a process that involves a reduction in muscle strength and anabolic hormone concentrations, which impacts significantly on health.

Aim: To study the hormone/total strength (H/TS) ratio as a proxy of anabolic insensitivity status in elders, and its relationship with disability, hospitalization, and mortality risk.

Design: A total of 1462 persons aged ≥65 years from the Toledo Study of Healthy Aging participated in this study. Serum concentrations of insulin like growth factor 1, total and free testosterone, dehydroepiandrosterone, dehydroepiandrosterone sulfate, and 17β-estradiol were measured. Total maximal voluntary isometric strength was obtained (handgrip, shoulder, hip, and knee) using standardized techniques and equipment. Physical activity was recorded by physical activity scale for the elderly questionnaire. Associations of the H/TS ratio with hospitalization and mortality were assessed using logistic regression models, and participants stratified into quartiles for each H/TS ratio.

Results: In women, all individual ratio H/TS models showed a strong to moderate increased risk for death and hospitalization. In men, all models revealed a significant positive association of the ratio H/TS with mortality rate but not for hospitalization (P < .01). Participants who have 2 or more H/TS ratios in the worst quartile increased the risk of hospitalization and mortality at least by 2-fold.

Conclusions: We demonstrate the main role that muscle function plays in the relationship between the hormonal status and hospitalization and mortality risk; this could be taken into consideration as a way to classify patients for hormonal therapy.

Keywords: Aging; anabolic status; disability; hospitalization; mortality; muscular strength.