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PubMed This is a summary of 18 peer-reviewed journal articles Updated
Urology

Understanding Your Prostate: Why BPH Happens

At a Glance

Benign prostatic hyperplasia (BPH) is a noncancerous, age-related growth of the prostate that may narrow the urethra and cause urinary symptoms. Prostate size alone does not determine severity, so evaluation considers symptoms, bladder function, urine testing, and PSA when appropriate.

If you are noticing changes in how you urinate, you are not alone. Benign Prostatic Hyperplasia, or BPH, is one of the most common age-related changes affecting men [1]. It is a natural, non-cancerous growth of the prostate gland that can sometimes squeeze the tube (urethra) that carries urine out of the body [2].

While the symptoms can be frustrating or even disruptive to your daily life, it is important to know that BPH is not cancer, and having an enlarged prostate does not mean you are at a higher risk for developing prostate cancer [3]. Understanding what is happening inside your body can help you move from feeling concerned to feeling in control of your health.

How Common is BPH?

While microscopic prostate changes are very common as men age, not every man develops a physically enlarged prostate, and even fewer develop bothersome symptoms.

Research into the likelihood of having microscopic histologic BPH (changes seen only under a microscope) shows it increases steadily with every decade of life:

  • In your 40s: Roughly 8% to 20% of men have early microscopic signs [1][4].
  • In your 60s: More than half (50–60%) of men have these changes [1].
  • In your 70s: Approximately 80% of men are affected [4].
  • Over age 90: Up to 90% of men have histologic BPH [5].

Despite these high numbers of microscopic changes, only about one-quarter of men with these cellular signs actually develop symptoms that require medical treatment [4].

The Biology of Growth

Your prostate is a small gland that sits just below the bladder. The growth associated with BPH happens specifically in the transition zone, the part of the prostate that wraps directly around the urethra [2].

This growth is driven by a complex “conversation” between different types of cells in the prostate. While the hormone dihydrotestosterone (DHT) plays a key role in signaling cells to divide, BPH is not caused by having “too much” testosterone [6]. Instead, it is fueled by:

  • Cellular Proliferation: Both the glandular cells (epithelium) and the supportive tissue (stroma) begin to multiply [7].
  • Inflammation: Chronic, low-grade inflammation can trigger the body’s “wound-healing” response, leading to further tissue growth and stiffening [8][9].
  • Growth Factors: Proteins like IGF-1 act as local messengers that tell the prostate tissue to keep expanding [10].

Making Sense of the Terms

When you talk to your doctor, you might hear several different terms used to describe your condition. They represent different parts of the same puzzle:

Term What it Means
Histologic BPH Microscopic growth in the prostate tissue. This is very common, may not cause symptoms, and is confirmed only if tissue is examined under a microscope [11].
Benign Prostatic Enlargement (BPE) A physical increase in the overall size of the prostate, usually estimated during a physical exam or measured by ultrasound [12].
Lower Urinary Tract Symptoms (LUTS) The actual symptoms you feel, such as a weak stream, frequent urges, or waking up at night to go [13].
Benign Prostatic Obstruction (BPO) When the enlarged prostate physically blocks the flow of urine out of the bladder [11].

Size vs. Symptoms: A Surprising Truth

One of the most important things to understand is that prostate size does not equal symptom severity [14]. You can have a very large prostate with almost no symptoms, or a slightly enlarged prostate that causes significant trouble [14].

This is because your symptoms are influenced by more than just the “clog” in the pipe. They are also affected by how well your bladder muscles can push, the level of inflammation in the tissue, and even the shape of the prostate—such as whether a small piece of tissue is poking up into the bladder (intravesical prostatic protrusion) [15][16].

Why You Should Seek Evaluation

Even if your symptoms seem like a minor nuisance, a baseline evaluation is important to identify the cause. Your doctor will tailor the tests to your specific symptoms, but an evaluation often includes:

  1. Medical History and Symptom Score: Using a tool like the IPSS (International Prostate Symptom Score) to measure how much your symptoms bother you [17].
  2. Physical Exam: A digital rectal exam (DRE) to feel the shape and firmness of the prostate [17]. (Note: DRE is not highly reliable for measuring exact volume).
  3. Urinalysis: To rule out infections or blood in the urine.
  4. Post-Void Residual (PVR): An optional ultrasound to see if your bladder is emptying completely [17][11]. Keep in mind, a high PVR could mean an obstruction, but it can also be caused by weak bladder muscles or certain medications.
  5. PSA Test: A blood test that may be offered to help estimate prostate volume or screen for prostate cancer, depending on your age and risk factors [17][11].

By identifying the cause of your symptoms, you and your doctor can decide whether monitoring with simple lifestyle changes is enough, or if it is time to consider treatments to improve your urinary health [18].

Common questions in this guide

What is BPH, and is it the same as prostate cancer?
BPH is a noncancerous growth of the prostate that becomes more common with age. It is not prostate cancer, and an enlarged prostate by itself does not mean a person has a higher risk of developing prostate cancer. BPH can still cause urinary symptoms if it presses on the urethra.
Why does benign prostatic hyperplasia happen?
BPH develops through age-related changes in how prostate cells grow. DHT, local growth signals, and low-grade inflammation can encourage glandular and supporting cells to multiply. It is not simply caused by having too much testosterone.
Does a larger prostate always cause worse urinary symptoms?
No. Some people have a large prostate with few symptoms, while a smaller enlargement can cause significant urinary trouble. Bladder muscle function, inflammation, and the shape of the prostate can also affect symptoms.
How common is BPH as men get older?
Microscopic signs of BPH occur in about 8% to 20% of men in their 40s, more than half of men in their 60s, and about 80% of men in their 70s. Up to 90% of men over age 90 may have these tissue changes, but only about one-quarter develop symptoms that require medical treatment.
What tests may be used to evaluate an enlarged prostate?
Evaluation may include a medical history, an IPSS symptom score, a digital rectal exam, and a urinalysis. A post-void residual ultrasound may check whether the bladder empties completely, and a PSA blood test may be considered based on age and risk factors. Your doctor will choose tests based on your symptoms and health history.
What urinary changes should I track before discussing BPH with a doctor?
Track how often you urinate, how many times you wake at night, whether you feel urgency or leakage, and whether your stream is weak or difficult to start. Also note straining and whether your bladder feels empty afterward. These details can help your doctor assess how much the symptoms affect you.

Questions to Ask Your Doctor

Curated prompts to bring to your next appointment.

  1. 1.What is my AUA Symptom Score (IPSS), and what does it tell us about the severity of my condition?
  2. 2.Based on my exam and ultrasound, what is my estimated prostate volume, and does it look like it's causing an obstruction?
  3. 3.Is my prostate size the main cause of my symptoms, or could other factors like bladder function or inflammation be involved?
  4. 4.What is my 'post-void residual' (PVR), and what does that number mean for my risk of complications?
  5. 5.How does my PSA level help you estimate my risk of symptom progression or future urinary retention?
  6. 6.Given my symptoms, should I start with lifestyle changes or is medical treatment recommended now?

Questions For You

Tap a prompt to share your answer — we'll use it plus this page's context to start a tailored conversation.

References

References (18)
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    Should magnetic resonance imaging be considered in every patient before a bladder outflow obstruction procedure?

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    Convective Water Vapor Energy for Lower Urinary Tract Symptoms/Benign Prostatic Hyperplasia.

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    Management of Benign Prostatic Hyperplasia in Older Adults.

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    The influence of asymptomatic inflammatory prostatitis on the onset and progression of lower urinary tract symptoms in men with histologic benign prostatic hyperplasia.

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    [Diagnostic work-up of benign prostatic hyperplasia : The German S2e-guideline 2023 part 1].

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This page explains how BPH develops and how prostate size, urinary symptoms, and evaluation fit together for educational purposes. It does not replace medical advice from your doctor or other healthcare professional.

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