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Prostate-Specific Antigen (PSA) by Immunoassay (Serum)

Published: August 9, 2026Updated: August 16, 2026

This test measures the level of prostate-specific antigen (PSA) in your blood. PSA is a protein produced by both healthy and cancerous prostate cells.

Quick summary

["PSA levels help assess prostate health and guide decisions about further testing or treatment."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
40784-1
Short code
Gp B Strep Ag Vag Ql
Synonyms
Gp B Strep Ag Vag Ql
Category
coagulation
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Specimen volume
5 mL
Stability
Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
500
Lipemia max
1000
Icterus max
500
TAT
4–24 hours
Order
routine

Why This Test Might Be Ordered

Your doctor may recommend a PSA test to monitor your prostate health, especially if you have symptoms like frequent urination, difficulty urinating, or pain in the pelvic area. It can also be used to screen for prostate cancer, especially in men at higher risk. PSA levels alone don’t diagnose cancer, but they help guide further evaluation.

What to Expect Before the Test

No special preparation is needed, but you may be asked to avoid ejaculation for 48 hours before the test. Drink plenty of water the day of your appointment to help your blood flow smoothly. Avoid heavy meals before testing.

What the Test Involves

A blood sample is taken from a vein in your arm. You may feel a slight pinch, but it usually takes only a few seconds. The sample is then sent to a lab for analysis.

What the Results Mean

Results are reported in nanograms per milliliter (ng/mL). A PSA level alone doesn’t indicate whether you have cancer, but it can help your doctor determine if additional tests are needed. Discuss your results with your healthcare provider.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

PSA

Frequently asked questions

What Are Common PSA Levels?
PSA levels vary widely among individuals. A low level may suggest normal prostate function, while higher levels can indicate prostate issues, including inflammation, infection, or cancer. Your doctor will consider your overall health, age, and other factors when interpreting results.
How Often Should I Get a PSA Test?
The frequency depends on your age, symptoms, and risk factors. The U.S. Preventive Services Task Force recommends against routine PSA screening for men under 55. Men aged 55–69 should discuss the benefits and risks with their doctor. Men over 70 may not benefit as much from screening.
Can Lifestyle Changes Affect PSA Levels?
Yes, certain lifestyle factors may influence PSA levels. Avoiding ejaculation for 48 hours before testing can give more accurate results. Regular exercise, a balanced diet, and avoiding smoking may support overall prostate health, but they don’t directly lower PSA levels.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy