What Causes an Enlarged Prostate?


At age 20, the prostate is about the size of a crab apple, but when a man reaches his mid-40s, the prostate cells accumulate in the area of the prostate that encircles the urethra and the organ tissue becomes overgrown, or enlarged. The increase in prostate cells is due to a slowing of apoptosis (normal programmed cell death), not an increase in cell production. This overgrowth of prostate tissue is called benign prostatic hyperplasia (BPH). By age 70, the average prostate has doubled in size.

In some men, the tissue overgrowth puts pressure on the urethra and ultimately restricts urine flow. The bladder must then work harder to push urine through the constricted tube. Over time, the overworked bladder develops a thickened wall, which reduces the organ’s capacity to store urine. In about half of men with BPH, these developments lead to urinary symptoms such as difficulty starting urination or a weak urine stream, increased urinary frequency or urgency, and painful urination.

BPH is the most common prostate problem for men older than age 50. It is estimated that 14 million men in the United States experienced lower urinary tract symptoms.

What triggers BPH is not well understood, but aging and testosterone (the predominant male sex hormone) are believed to be the primary influences on its development. The female sex hormone estrogen (produced in small amounts in men) also may play a role, perhaps when a man’s testosterone production declines and the balance of the two hormones is altered.

The good news is that unless symptoms are bothersome, treatment is not required for this condition. More good news: Research to date does not indicate a connection between BPH and the development of prostate cancer.