Causes and effects
In BPH, cells in the prostate gland divide and multiply. That’s what causes the gland to expand in size. Research has found that prostate volume averages about 25 cubic centimeters (cc) for men in their 30s, when BPH is rare. But it’s common for the gland to get bigger with time, reaching an average of 35 to 45 cc for men in their 70s.
Prostate enlargement doesn’t always cause urinary problems. Some men have relatively large prostates without having any symptoms. On the other hand, symptoms can occur even in men with a small or average prostate.
The prostate is made up of muscle tissue and a network of tiny tubes (ducts) lined with cells that produce prostatic fluid. During ejaculation, the prostate pushes that fluid through those ducts and into the urethra, where it mixes with sperm cells from the testes and exits through the penis. BPH is the result of cell overgrowth in the muscle as well as the lining of the ducts. Experts think it has to do with age-related changes in hormone levels.
Certain factors are linked to a higher risk of BPH. These risk factors include increasing age, a family history of BPH, higher body weight, and lack of exercise. It’s not clear whether losing weight or exercising more actually prevents BPH, but these risk factors can identify men who are the most likely to develop prostate enlargement with bothersome urinary problems. (See “Can BPH be prevented?” on page 20.)
The prostate wraps entirely around the urethra at the point where it exits the bladder. As the prostate grows, it starts to press in on the urethra and restrict the flow of urine. As a result, it gets harder to empty your bladder. Over time, this can also lead to changes in how the bladder itself functions. In some cases, the impingement can get so extreme that you can’t urinate at all—a painful medical emergency that poses the risk of kidney damage.