Longitudinal relationships of circulating reproductive hormone with functional disability, muscle mass, and strength in community-dwelling older men: the Concord Health and Ageing in Men project.

Abstract

The relationship between functional disability and reproductive hormones and whether it is mediated by muscle mass and strength in older men are unclear. The objective of the study was to identify the relationships between hormones and change in functional disability over a 2-year follow-up and to examine whether muscle mass and strength explain any of the observed relationships. A total of 1318 men aged 70 years and older from the Concord Health and Ageing in Men Project study were assessed at both baseline and 2-year follow-up. T, DHT, estradiol (E2), and estrone (E1) were measured by liquid chromatography-tandem mass spectrometry and SHBG, LH, and FSH by immunoassay. Functional disability was measured by basic Activities of Daily Living scale at both time points. Grip and quadricep strength were measured using dynamometers and lean (muscle) mass was determined by dual X-ray absorptiometry. All hormones were significantly associated with functional decline in univariate analyses. Only T, E2, E1, and calculated free T remained associated in multivariate analyses. Men in the lowest T quartile (vs the highest quartile) had an increased risk functional decline (odds ratio 1.96, 95% confidence interval 1.01-3.82). Similar associations were observed in E2, E1, and calculated free T. When muscle variables were added into the multivariate model, the associations between these hormones and functional decline were no longer statistically significant. Low T, E2, and E1 were significantly associated with prospective functional decline over 2 years. This relationship was no longer significant when muscle mass or strength were added, suggesting that the hormonal associations are mediated through their sequential effect on muscle mass and strength.