Prostate-Specific Antigen (PSA)

PSA (Prostate-Specific Antigen) Test

Results

A prostate-specific antigen (PSA) test measures the amount of prostate-specific antigen in the blood. Normal values may vary from lab to lab.

Normal

Because normal PSA levels seem to increase with age, age-specific ranges may be used. However, the use of age-specific ranges is controversial, and some doctors prefer to use one range for all ages. For this reason, it is important to discuss your test results with your doctor. This table is a reference for white males. Results for black and Asian males are slightly different.

Total prostate-specific antigen (PSA)

Men younger than 40:	Less than 2.5 nanograms per milliliter (ng/mL)	Less than 2.5 micrograms per liter (mcg/L) (SI units)
Men age 40 to 50:	0–2.5 ng/mL	0–2.5 mcg/L
Men age 51 to 60:	0–3.5 ng/mL	0–3.5 mcg/L
Men age 61 to 70:	0–4.5 ng/mL	0–4.5 mcg/L
Men over age 70:	0–6.5 ng/mL	0–6.5 mcg/L

High values

• PSA levels from 4 to 10 ng/mL: About 20% to 30% of men (20 to 30 men in 100) with PSA levels in this range may have prostate cancer. A transrectal ultrasound (TRUS) and prostate biopsy are needed to confirm a diagnosis of cancer.
• PSA levels above 10 ng/mL: About 40% to 60% of men (40 to 60 men in 100) with PSA levels in this range may have prostate cancer. A transrectal ultrasound (TRUS) and prostate biopsy are needed to confirm cancer.
• High levels do not always mean prostate cancer is present. PSA levels may be high if the prostate gland is enlarged (benign prostatic hypertrophy, or BPH) or inflamed (prostatitis).

A follow-up test, percent free prostate-specific antigen (free PSA), may be used to see if a prostate biopsy should be done to check for cancer. Men with a low percentage of free PSA have a higher chance of developing cancer as shown in the table below.

Free prostate-specific antigen (fPSA)

Percent free PSA	Probability of cancer
Greater than 25%:	8%
20%–25%:	16%
15%–20%:	20%
10%–15%:	28%
0–10%:	56%

Low free PSA values (less than 15%) are more likely to be caused by prostate cancer than high free PSA values.

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Author:	Ralph Poore	Last Updated: May 15, 2007
Medical Review:	Martin Gabica, MD - Family Medicine Christopher G. Wood, MD, FACS - Urology/Oncology
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