Introduction While much research relating sex hormones to bone health has centred on oestrogen deficiency in postmenopausal women, far less is known regarding the potential for sex hormone levels to influence bone health in men. We investigated the influence of sex hormone concentrations on bone health in men at age 50, using data from the Newcastle Thousand Families Study.

Methods The study included 171 men who attended for DEXA scanning (giving measures of bone mineral density (BMD) for the hip and lumbar spine) and also gave blood samples allowing measurement of concentrations of testosterone, oestradiol, sex hormone binding globulin (SHBG), free androgen index (FAI), free oestrogen index (FEI), luteinising hormone (LH), follicle stimulating hormone (FSH), free testosterone and serum β C-telopeptide of type 1 collagen (CTX), a biochemical marker of bone resorption.

Results There were significant correlations between total hip BMD and FEI (p=0.03), total spine BMD and SHBG (p=0.006), FEI (p=0.008) and FAI (p=0.008) and serum CTX and free testosterone (p=0.016). After adjustment for body weight the only associations that remained were between total spine BMD and FAI (p=0.046) and between serum CTX and free testosterone (p=0.014).

Conclusions Our results suggest that while there are associations between serum sex hormone concentrations and BMD, they are mostly explained by an adjustment for contemporary body weight. The inverse association between serum CTX and free testosterone is more robust, remaining significant after adjustment. This suggests that free testosterone levels are independently associated with bone resorption levels.