Researchers at the Department of Renal and Urologic Surgery at Japan’s Asahikawa Medical University examined the effect of dutasteride, a 5α-reductase inhibitor, on the bone mineral density (BMD) of aging male patients with lower urinary tract symptoms (LUTS) to understand the relationship between changes in testosterone and BMD.
The research paper, “Dutasteride improves bone mineral density in male patients with lower urinary tract symptoms and prostatic enlargement: a preliminary study,” was published in The Aging Male.
Benign prostatic hyperplasia (BPH) and consequent lower urinary tract symptoms result from extended proliferation of smooth muscle and epithelial cells due to the effect of an androgen hormone (dihydrotestosterone, or DHT). This hormone is synthesized from testosterone through the action of enzymes called 5-α-reductases, which are active in the prostate and also contribute to tissue vascularization.
Drugs that inhibit these specific enzymes, such as dutasteride, are used in the treatment of BPH. Dutasteride has been shown to reduce prostatic volume, inhibit DHT, and elevate serum testosterone levels to some extent.
Testosterone plays many physiological roles. When levels decrease as men age, it is associated with sexual dysfunction, fatigue, depression, and muscle and bone weakness. Although osteoporosis is associated more with women’s health, bone fracture and osteoporosis have also been associated with men’s aging and mortality. There is an overlap between aging men with decreased bone density and LUTS associated with prostatic enlargement. But few studies have investigated the effect of dutasteride’s 5a-reductase inhibition on BMD in men with LUTS associated with prostatic enlargement.
The team studied 17 patients with LUTS and enlarged prostate, assessing the International Prostate Symptom Score (IPSS), prostatic volume (PV), serum prostatic-specific antigen (PSA), and testosterone before and one year after therapy with dutasteride (0.5 mg daily). Bone mineral density (BMD) in the lumbar and femur was also measured.
The results revealed that dutasteride significantly reduced PV, decreased serum PSA, and improved IPSS. Serum testosterone was not changed significantly and only the BMD of the femur was significantly improved. In the nine men whose testosterone was increased after dutasteride treatment, BMD of the lumbar and femur was significantly improved.
Researchers emphasized that a large-scale, placebo-controlled study is needed to confirm the effects of the drug on men’s bone health, but concluded that “dutasteride has a potential to improve BMD with elevation of serum testosterone in aging male patients with LUTS and prostatic enlargement.”