The prostate gland is approximately the size of a walnut. Located in front of the rectum and beneath the bladder, it is surrounded by fibrous tissue capsule known as the prostate capsule. The tube that transports urine and sperm—the urethra—begins at the neck of the bladder and travels through the prostate gland.

The BPH Process
BPH rarely causes symptoms before age 40, but more than half of men in their sixties and as many as 90 percent in their seventies and eighties have some symptoms of BPH (Source: National Institutes of Health).

The precise cause of BPH—benign prostatic hyperplasia—is still being researched. It is commonly believed, however, that the levels of two hormones produced by the testes (testosterone, which is converted into dihydrotestosterone or DHT, and estradiol, or estrogen) rise as men age. This leads to growth (hyperplasia) in benign (non-cancerous) prostate cells.

As the prostate enlarges, the layer of tissue surrounding it stops it from expanding, causing the gland to press against the urethra like a clamp on a garden hose. The bladder wall becomes thicker and irritable. The bladder begins to contract even when it contains small amounts of urine, causing more frequent urination. Eventually, the bladder weakens and loses the ability to empty itself. Urine remains in the bladder. The narrowing of the urethra and partial emptying of the bladder cause many of the problems associated with BPH.