Abstract
Testosterone and oestradiol are critical for normal bone development and maintenance in men. With ageing, there is a decrease in both androgen and oestrogen concentrations, which is associated with low bone mineral density (BMD). Aromatase inhibitor therapy decreases oestradiol concentration by blocking its conversion from testosterone. This study assessed the effect of aromatase inhibition on BMD in older men with lower testosterone concentrations.
Men (n = 88) with low or borderline-low testosterone concentration were randomized to receive anastrazole or placebo for 12 months, with reviews at three, six and 12 months. Nineteen subjects dropped out of the study, leaving a study population of 69. Testosterone was measured by radioimmunoassay, bioavailable testosterone by differential precipitation with ammonium sulphate and BMD by DEXA scanning.
In the group receiving anastrazole, mean testosterone concentration increased from 11.1 ± 3.2 nmol/L at baseline to 18.2 ± 4.8 nmol/L at three months. Oestradiol decreased from 55 ± 15 to 44 ± 15 nmol/L. Spine BMD decreased from 1.12 ± 0.14 to 1.10 ± 0.14 g/cm2 in the group receiving anastrazole, while it increased in the placebo group from 1.18 ± 0.15 to 1.19 ± 0.15 g/cm2.
Anastrazole increased serum testosterone and modestly reduced oestradiol concentrations while decreasing BMD compared with placebo. Aromatase inhibition does not appear to be an optimal treatment for hypogonadal men and does not improve their skeletal health.