The prostate is a small, walnut-sized gland found only in men, sitting just below the bladder and wrapped around the tube that carries urine out of the body. It produces fluid that mixes with sperm to form semen, making it essential for reproduction. Despite its small size, the prostate is one of the most common sources of health problems in men as they age, from benign enlargement to cancer.
Where the Prostate Sits
The prostate sits in the lower pelvis, directly beneath the bladder. It wraps around the upper portion of the urethra (the tube urine flows through), which is why prostate problems so often affect urination. Its shape resembles an upside-down cone: the wider base connects to the bladder neck above, while the narrower tip points downward toward the pelvic floor muscles.
Behind the prostate, separated by a thin layer of tissue, sits the rectum. This close relationship is why doctors can feel the prostate through a rectal exam. On either side, the gland rests against the pelvic floor muscles that help control bladder function. A healthy prostate measures roughly 3 by 3 by 5 centimeters, about the volume of a large walnut, and has a smooth, rubbery texture.
What the Prostate Does
The prostate’s primary job is producing a thin, milky fluid that makes up a significant portion of semen. This fluid contains enzymes that thin semen after ejaculation, helping sperm move freely. It also contains a hormone-like substance that supports sperm motility, giving sperm cells the ability to swim toward an egg. Without healthy prostatic fluid, sperm function and male fertility decline.
One of the enzymes the prostate produces is prostate-specific antigen, or PSA. In semen, PSA liquefies the fluid so sperm can be released. Small amounts of PSA also leak into the bloodstream, which is why a blood test can measure PSA levels as a screening tool for prostate problems.
How the Prostate Changes With Age
The prostate is one of the few organs that keeps growing throughout a man’s life. This growth is driven by a potent form of testosterone called dihydrotestosterone, or DHT. The body converts circulating testosterone into DHT inside prostate tissue, and DHT then stimulates the gland’s cells to multiply. This process operates through a kind of self-amplifying loop: even small amounts of DHT trigger the production of more DHT, which fuels further growth.
In younger men, this growth is part of normal development. But after about age 40, continued expansion of the gland can start causing problems. Because the prostate surrounds the urethra, any increase in size squeezes the urinary passage from the outside. This is the basic mechanism behind most age-related prostate symptoms.
Benign Prostatic Hyperplasia (BPH)
The most common prostate condition is benign prostatic hyperplasia, a noncancerous enlargement that affects the majority of men by their 60s and 70s. BPH develops when cells in the inner zone of the prostate, the area closest to the urethra, begin multiplying. As this zone expands, it compresses the urethra and obstructs the bladder outlet.
The symptoms are familiar to many older men: a weak or interrupted urine stream, difficulty starting urination, needing to urinate frequently (especially at night), and a feeling that the bladder hasn’t fully emptied. In some cases, the middle portion of the prostate can enlarge upward into the bladder itself, creating a flap-like effect that further blocks urine flow during voiding. Over time, the bladder has to work harder to push urine past the obstruction, and incomplete emptying can raise the risk of urinary tract infections.
BPH is not prostate cancer and does not increase your cancer risk, but the symptoms overlap enough that both conditions need to be evaluated by a doctor.
Prostatitis
Prostatitis refers to inflammation of the prostate, and it can affect men of any age. There are several distinct types, each with different causes and timelines.
- Acute bacterial prostatitis is a sudden infection, usually caused by common gut bacteria. It hits hard, with fever, chills, muscle aches, severe pain during urination, and pelvic pain. This type requires prompt treatment.
- Chronic bacterial prostatitis involves a persistent or recurring urinary tract infection that lingers for three months or longer. Symptoms are similar but less intense than the acute form.
- Chronic pelvic pain syndrome is the most common and most frustrating type. It causes ongoing pain in the pelvic area, genitals, or lower back without any detectable infection. The cause is often unclear, and it can be subdivided into inflammatory and non-inflammatory forms based on lab findings.
- Asymptomatic inflammatory prostatitis produces no symptoms at all. It’s typically discovered incidentally during a biopsy or semen analysis done for another reason and generally doesn’t require treatment.
Prostate Cancer
Prostate cancer is the most commonly diagnosed cancer in men in the United States. Based on recent data, roughly 333,800 new cases are expected in 2026 alone, at a rate of about 123 per 100,000 men per year. Most prostate cancers grow slowly, and many men diagnosed with it live for years or decades without the disease causing serious harm. However, an estimated 36,320 men die from it annually, so it is not universally harmless.
Early prostate cancer rarely produces symptoms. When it does, signs can include difficulty urinating, blood in the urine or semen, or new pain in the hips or lower back. Because early-stage cancer is silent, screening plays an important role in detection.
How the Prostate Is Checked
Two main tools are used to evaluate prostate health: the digital rectal exam and the PSA blood test.
During a rectal exam, a doctor inserts a gloved finger into the rectum to feel the back surface of the prostate. A healthy gland feels smooth, rubbery, and firm, with a noticeable groove between its two lobes. It should be painless to the touch. What doctors are looking for are irregularities: hard spots, lumps, asymmetry, tenderness, or an unusually large gland. The exam takes only a few seconds and provides real-time physical information that blood tests cannot.
The PSA test measures the level of prostate-specific antigen circulating in your blood. There is no single number that definitively separates normal from abnormal. A PSA above 4.0 ng/mL is the traditional threshold that may prompt further evaluation, but context matters. PSA rises naturally with age, so some doctors use a cutoff of 2.5 ng/mL for younger men and 5.0 ng/mL for older men. Certain medications used to treat prostate enlargement also lower PSA levels, which needs to be factored in when interpreting results. An elevated PSA does not mean cancer is present. BPH, prostatitis, recent physical activity, and even ejaculation can temporarily raise PSA levels.
When either screening tool raises concern, additional steps like imaging or a tissue biopsy help clarify the diagnosis.