Abstracts - Orals, Featured Poster Presentations, and Posters
OR12-Reproductive Hormones: Vital Effects Evidenced In Human Cohorts & Experimental Models
Presentation Start Time: 11:45 AM
Room 102 (Moscone Center)
As men age, testosterone (T) levels decline, estradiol (E2) levels either decline or remain stable, and sex hormone-binding globulin (SHBG) levels increase. Compared with T, E2 has a stronger influence on bone strength, an observation confirmed in our Boston Area Community Health/Bone (BACH/Bone) Survey. There are, however, relatively few population-based studies of men which have examined the longitudinal associations of T, E2, and SHBG with bone loss. The objective of this study was to examine the relation of total T (TT), total E2 (TE2), and SHBG with bone loss at the femoral neck. We used data from the BACH/Bone Survey, a population-based cohort study of 1219 racially diverse men. Subjects were examined at baseline and follow-up visits. Femoral neck bone mineral density (fnBMD) was assessed by dual x-ray absorptiometry (DXA) using the same scanner at baseline and follow-up. Multivariable linear regression was used to examine the independent associations of baseline TT, SHBG (both by immunoassay), and TE2 (mass spectrometry) concentrations (quartiles (Q) and continuous) with percent (%) change in fnBMD, controlled for baseline fnBMD, age, race/ethnicity, income, smoking, type 2 diabetes mellitus, self-rated health, and DXA-derived total body fat and lean mass. A total of 692 men (70% of eligible men) with mean±SD baseline age 51±12y completed follow-up examinations 7.0±0.6y later. Mean±SD TT was 425±169ng/dL, TE2 was 24.01±9.71pg/mL, and SHBG was 35.34±17.09nmol/L. Estimated (relative standard error; RSE) % decline in fnBMD was 5.0(0.2)% during follow-up (annualized decline, 0.71%/y). Mean fnBMD declines were 5.7(0.5)% in Q1 of TT compared with 6.2(0.5)% among men in Q4; for TE2, fnBMD declined by 5.0(0.6)% in Q1 vs. 5.8(0.6)% in Q4; for SHBG, fnBMD declined by 5.1(0.5)% in Q1 vs. 6.0(0.5)% in Q4. In a multivariable model with TT, TE2, SHBG, and covariates, SHBG (Q, p=0.08, continuous, p=0.01) but not TT (Q, p=0.15, continuous, p=0.27) or E2 (Q, p=0.66, continuous, p=0.52) was significantly associated with change in fnBMD. Based on this model, decline in fnBMD was 1.0(0.4)% greater with each SD increase in SHBG. The SHBG-associated decline in fnBMD appeared to be most pronounced in black men, with each SD increase in SHBG associated with an additional 1.6% decrease in fnBMD (vs. white men), but age did not modify the relation of SHBG with decline in fnBMD. In conclusion, declines in fnBMD in this relatively young and racially diverse population-based cohort of men are consistent with previous studies. These data support mounting evidence for SHBG either having an independent effect on, or being a marker of, health outcomes of relevance to the health of aging men.
Disclosure: ABA: Principal Investigator, Abbott Laboratories, Principal Investigator, GlaxoSmithKline, Consultant, Lilly USA, LLC. Nothing to Disclose: RC, SC, ND, GC, ES, RG, JA, CGW, BB
*Please take note of The Endocrine Society's News Embargo Policy at http://www.endo-society.org/endo2013/media.cfm
Sources of Research Support:
The BACH/Bone Survey was supported by grant R01AG020727 from the National Institute on Aging (NIA). The content is solely the responsibility of the authors and does not necessarily represent the official views of NIA.