With age, the prostate gland tends to increase in size for reasons that are poorly understood at present, although it appears that the endocrine system plays a role. The incidence of this disorder, which afflicts only about one out of five men in their 40s, rises to one in four men by age 55, one in two by age 75, and four out of every five men over the age of 80.

The gland's location, beneath the bladder and around the urethra, coupled with the fact that benign hypertrophy particularly affects the prostate tissues immediately surrounding the urethra, accounts for the hallmark and often most troubling symptom of the disorder: diminished force and caliber of the urinary stream. The more significant the overgrowth of the tissue becomes, the more difficulty men will have in getting a urine stream started, maintaining a strong and forceful flow, and stopping the flow without dribbles and spurts of urine. With time, the enlarged gland can protrude into the bladder, often partially blocking the opening to the urethra within the bladder and making it difficult for the bladder to completely empty. Urine remaining in the bladder after urination (called post-void residual urine) forms a hospitable environment for bacterial growth as well as for the formation of sediment that could lead to bladder gravel or stones.

Occasionally, the enlarged gland suddenly swells and occludes the outflow of urine. The enlargement of the prostate usually involves both the secretory glands and the muscle of the prostate. Certain antihistamine preparations commonly found in both prescription and over-the-counter cold remedies can cause the muscle of the prostate to contract, resulting in urinary retention.

Symptoms

Reduced caliber and force of urine stream; awakening frequently to urinate at night; urgent need to urinate. Enlarged prostate on rectal exam.

Treatment

Medical treatment is aimed at reducing the influence of testosterone (the male reproductive hormone) on the gland or relaxing the muscle of the prostate gland. The medication finasteride (Proscar) offers the benefit of decreasing testosterone influence without diminishing sexual drive, and in general should be used in men with very large prostate glands. Medications such as alpha blockers, which relax the muscle of the prostate, offer relief of symptoms and improved urinary flow regardless of prostate size.

As the gland grows larger or the symptoms more severe, surgery often becomes necessary to relieve the obstruction. The surgery can be performed through an abdominal incision or more commonly, through the urethra.