What the prostate does

Location explains the symptoms

The prostate lies just below the bladder and in front of the rectum. Because a clinician can reach the back surface of the gland through the rectum, a digital rectal exam is sometimes part of an evaluation when a man has symptoms. That exam is not the same thing as a decision to screen every man without symptoms. The U.S. Preventive Services Task Force has said the rectal exam was not established as a screening test in the major screening trials.

The gland wraps around the urethra. When it enlarges, it can press on the bladder and narrow that tube. MedlinePlus describes the result: urine may start slowly, stop and start, or feel incomplete. Over time the bladder muscle can tire from pushing through a narrower opening, which adds urgency and nighttime trips.

What the gland adds to semen

The prostate makes fluid that is part of semen. That role is why treatments involving the prostate, including some medicines and procedures, can change ejaculation or sexual function. Those effects are a reason to ask about tradeoffs before a treatment, not a reason to avoid care for a symptom that is already causing harm.

The gland depends on male hormones. Testosterone is converted in the body to dihydrotestosterone, often called DHT. The National Cancer Institute notes that DHT supports normal prostate growth and may also play a part in enlargement and in the development of prostate cancer. That biology is why some prescription medicines block the conversion. Those medicines are not supplements, and they have side effects. They are discussed in a separate article because the decision to use them belongs with a prescriber.

PSA is a protein, not a diagnosis

Prostate-specific antigen, or PSA, is a protein made mainly by prostate cells. A blood test measures how much of it is circulating. Cancer can raise PSA. So can enlargement and inflammation. A high number is a clue, not a verdict, and a low number does not promise that cancer is absent. The National Cancer Institute’s patient screening summary says there is no standard routine screening test, and that it is not clear that finding cancer earlier lowers the chance of dying from it. The 2018 statement from the U.S. Preventive Services Task Force describes a small possible reduction in prostate-cancer deaths for some men ages 55 to 69, alongside important harms. Those two public sources do not speak with one voice, which is why a screening article on this site presents both and asks men to check the current recommendation.

What this anatomy does not tell you

Knowing where the prostate sits will not identify the cause of your symptoms. Fever, the inability to pass any urine, or blood in the urine are reasons to get medical help quickly. Mild, long-standing changes in flow are a reason to make an ordinary appointment and to mention every medicine you take, including nonprescription cold remedies and supplements.