Age, obesity and inflammation at baseline predict the effects of testosterone administration on the metabolic syndrome.

BACKGROUND Testosterone administration to hypogonadal men improves the metabolic syndrome. This study analyzed whether age, serum testosterone, body mass index/waist circumference, increment in testosterone values and C-reactive protein (CRP) predicted the outcome of testosterone administration. MATERIALS AND METHODS A total of 110 mainly elderly men, aged between 18 and 83 years (mean±SD=59.6±8.0) with baseline serum testosterone of 5.8-12.1 nmol/L (mean±SD=9.3±1.7) (n>14.0 nmol/L), received parenteral testosterone undecanoate whereupon serum testosterone normalized between 3 and 24 months. RESULTS (i) The lower the baseline testosterone, the stronger the decreases in waist size and triglycerides. (ii) The greater the increment in serum testosterone, the stronger the decreases in low-density lipoprotein (LDL) cholesterol, triglycerides and glucose. (iii) Older age was associated with stronger beneficial effects on waist size, glucose and all lipids, but a small negative effect on high-density lipoprotein cholesterol. (iv) Obese men and men with the largest waist circumference showed the strongest declines over 2 years in weight, waist circumference and body mass index (BMI), and also in total cholesterol, triglycerides and glucose. Baseline BMI predicted a stronger decline in LDL cholesterol, but a smaller decline in CRP levels. (v) Higher baseline CRP predicted larger declines in levels of triglycerides, glucose and CRP. (vi) In the multivariate model, age, BMI and CRP were independent predictors of the strongest benefit of testosterone treatment on the metabolic syndrome. CONCLUSIONS Older men, particularly when obese with chronic low-grade inflammation benefited most of normalizing their testosterone levels, preferably if they reached mid-normal reference values.