Decrease of serum testosterone by cyproterone acetate accompanied by an unexpected increase of calcitonin secretion capacity.

The interaction between testosterone and calcitonin secretion capacity was studied in 9 patients with prostatic cancer. Treatment with the antiandrogenic agent cyproterone acetate resulted in an expected decrease in serum testosterone but an unexpected and unexplained increase in calcitonin secretion capacity. The previous statement that a positive correlation between sex hormones and calcitonin secretion capacity can be recognized probably requires revision. This unexpected effect of cyproterone acetate had possible additive beneficial advantages for treatment, such as bone mass sparing and its analgesic effect.