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

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

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

Quick summary

["PSA screening helps detect early signs of prostate issues, including potential cancer."]

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

Key facts at a glance

LOINC
17298-1
Short code
Deprecated M TB rRNA XXX Ql Prb
Synonyms
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Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
probe
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 healthcare provider may recommend a PSA screening test if you’re at higher risk for prostate cancer—such as men over 50, those with a family history, or those with certain health conditions. It can also be used to monitor existing prostate health or guide treatment decisions.

What to Expect Before the Test

No special preparation is needed, but you may be asked to avoid ejaculation for 2–3 days before testing. Drink plenty of water the day of your visit to help your blood flow smoothly.

What Happens During the Test

A healthcare professional will draw blood from a vein in your arm. The sample is sent to a lab for PSA measurement using an immunoassay method, which detects the protein in your blood.

What the Results Mean

PSA levels alone don’t diagnose prostate cancer—they’re part of a broader evaluation. Results may be used alongside other tests (like a digital rectal exam or biopsy) to assess risk.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

PSA Screen

Frequently asked questions

What causes PSA levels to change?
PSA levels can rise due to prostate inflammation, infections, or benign growths. They may also fluctuate with age, exercise, ejaculation, or certain medications.
How often should I get a PSA test?
The frequency depends on your age, health history, and risk factors. Your doctor will recommend a schedule based on your individual needs, not just a standard guideline.
Can PSA levels be affected by diet or supplements?
Some foods (like cruciferous vegetables) or supplements (like saw palmetto) may influence PSA levels, but the effect is usually small. Always check with your provider before making changes.
  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