Introduction: The prevalence of bone density loss (BDL), including osteopenia and osteoporosis, is higher in men with low testosterone (T). It is unclear if total T (TT) of free T (FT) levels are more important in BDL development. This retrospective study aimed to evaluate the associations of TT and FT to BDL.
Methods: Men with low serum T ( <300 ng/dl on 2 early morning levels) routinely undergo dual-energy X-ray absorptiometry (DEXA). The sample included men who had a DEXA scan and T labs collected within 6 months of each other. Total hip, femoral neck, and lumbar spine were scanned. TT was measured using LCMS, FT using equilibrium dialysis. On DEXA, osteopenia was defined as T score -1.1 to -2.5, osteoporosis T score lower than -2.5. Comorbidities assessed included history of diabetes, and obstructive sleep apnea(OSA). We report rates of osteopenia and osteoporosis and attempted to define the ability of TT and FT to predict BDL.
Results: 744 men were analyzed with mean age of 62 ± 11 years. Mean TT and FT were 320 ± 194 ng/dL and 29 ± 37 ng/dL. Median number of comorbidities was 2 (1,2). 21% had DM, 31% reported OSA, and 51% of the men had = 2 comorbidities. DEXA showed 38% had osteopenia, 5% osteoporosis. Free T (OR per 10 ng/dL= 1.05, 95% CI = 1.00 – 1.09), but not total T, was significantly associated with bone density loss (either osteopenia or osteoporosis), even after adjustment for age, diabetes, and OSA.
Conclusions: In our cohort of men with low T, BDL is highly prevalent. Age, diabetes and OSA are significant predictors of BDL. Lower FT increased the likelihood of BDL after adjusted by age, diabetes and OSA. This was not observed with TT.
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