The effect of 5alpha-reductase inhibition with finasteride and dutasteride on bone mineral density in older men with benign prostatic hyperplasia.

Testosterone is converted to dihyrotestosterone by two isoenzymes of 5alpha-reductase. Finasteride and dutasteride are 5alpha-reductase inhibitors commonly used in the treatment of benign prostatic hyperplasia. We compared indices of bone mineral density in 50 men treated with finasteride, 50 men treated with dutasteride and 50 men as control. Bone mineral density of spine and hip were measured using dual energy X-ray absorptiometry. Bone formation was assessed by measuring serum osteocalcin and bone resorptionby measuring serum C-terminal telopeptide of collagen type 1. In addition serum total testosteron and estradiol were determined. The dutasteride group had significantly higher mean bone min- eral density, mean bone mineral content, mean T score, mean Z score at femoral neck and mean total hip Z score than control. Mean total testosterone and estradiol levels were higher in the dutasteride group. There were no significant dif- ferences between the groups in lumbar spine bone density parameters or bone turnover markers. Our results provide evidence that long-term 5alpha-reductase suppression does not adversely affect bone mineral density. Dutasteride therapy could have beneficial effect on bone density.