PSA (Prostate-Specific Antigen)

What is PSA?

PSA (prostate-specific antigen) is a protein produced by cells in the prostate gland. Small amounts normally leak into the bloodstream, but levels rise when the prostate is enlarged, inflamed, or cancerous.

The PSA blood test measures the concentration of this protein in your blood. It's primarily used to screen for prostate cancer in men over 50, though elevated PSA doesn't automatically mean cancer.

Normal Ranges

PSA levels increase naturally with age as the prostate enlarges:

Age Group	Normal PSA
40–49	Below 2.5 ng/mL
50–59	Below 3.5 ng/mL
60–69	Below 4.5 ng/mL
70–79	Below 6.5 ng/mL

Many labs use a general cutoff of 4.0 ng/mL, but age-specific ranges are more accurate.

Why It Matters

Prostate Cancer Screening

PSA testing can detect prostate cancer early, often before symptoms appear. Early detection allows for more treatment options and better outcomes.

Monitoring After Treatment

For men who've had prostate cancer treatment, regular PSA tests check for recurrence. Rising PSA after treatment suggests cancer may be returning.

Detecting Prostate Conditions

Elevated PSA can also indicate:

• Benign prostatic hyperplasia (BPH) — Non-cancerous prostate enlargement
• Prostatitis — Infection or inflammation of the prostate

Limitations of PSA Testing

PSA testing is controversial because:

High PSA doesn't mean cancer. Many factors raise PSA without cancer being present.

Normal PSA doesn't rule out cancer. About 15% of men with prostate cancer have normal PSA levels.

Not all prostate cancers need treatment. Some are slow-growing and may never cause problems.

This is why PSA results are considered alongside other factors: age, family history, digital rectal exam, and sometimes MRI or biopsy.

What Raises PSA (Besides Cancer)

• Benign prostatic hyperplasia (BPH) — Common with aging
• Prostatitis — Infection or inflammation
• Recent ejaculation — Wait 48 hours before testing
• Vigorous exercise — Especially cycling
• Urinary tract infection
• Recent prostate exam or catheterization

PSA Velocity and Doubling Time

How PSA changes over time can be more informative than a single value:

• PSA velocity: How much PSA increases per year (rapid rise is concerning)
• PSA doubling time: How long it takes PSA to double (shorter time suggests aggressive cancer)

Should You Get a PSA Test?

Screening recommendations vary:

Age 55–69: Discuss with your doctor. Consider family history, race, and personal preference.

Over 70: Routine screening generally not recommended unless high risk.

Family history of prostate cancer or African descent: Consider starting screening earlier (age 40–45).

How Often to Test

• First baseline test: Age 40–45 for high-risk groups, 50 for average risk
• If PSA is low: Every 2–4 years
• If PSA is borderline or rising: Annually or more frequently

Related Biomarkers

• Free PSA (helps distinguish cancer from BPH)
• PSA density (PSA level relative to prostate size)
• PHI (Prostate Health Index)