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

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

This test measures a protein produced mainly by prostate cells, often used to screen for or monitor prostate health, including potential cancer.

Quick summary

["PSA helps assess prostate health but isn’t definitive for cancer alone—results should be discussed with your doctor."]

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

Key facts at a glance

LOINC
76089-2
Short code
RSV RNA Nph Ql NAA+probe
Synonyms
RSV RNA Nph Ql NAA+probe
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-amp-tar
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 Is Done

Your doctor may order a PSA test to check for prostate issues, such as an enlarged prostate (benign prostatic hyperplasia), infection, or prostate cancer. It can also help monitor treatment progress if you’ve been diagnosed with prostate cancer or another prostate condition.

What to Expect Before the Test

No special preparation is needed, but avoid ejaculation 2–3 days before testing. If you have recent prostate exams (like a biopsy), your doctor may advise waiting a few weeks to avoid false results.

How the Test Works

A small blood sample is taken from your arm. The lab uses an immunoassay (a sensitive detection method) to measure PSA levels in your serum or plasma.

What the Results Mean

PSA levels vary by age, health, and other factors. A low PSA might suggest normal prostate function, while higher levels can signal potential concerns. Your doctor will interpret results in the context of your medical history and symptoms.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

PSA Probe

Frequently asked questions

What does a high PSA level mean?
A high PSA level can indicate prostate issues, but it doesn’t confirm cancer alone. Other conditions (like infection, inflammation, or an enlarged prostate) can also raise PSA. Your doctor will consider additional tests or factors to guide next steps.
How often should I get this test?
The frequency depends on your health. Routine PSA screening isn’t recommended for everyone; it’s typically advised for men at higher risk (e.g., age 55+ with family history) or those with symptoms. Always follow your doctor’s guidance.
Can diet or exercise affect PSA levels?
Yes, certain foods (like cruciferous vegetables) or medications (e.g., finasteride) may influence PSA levels. Exercise generally supports prostate health, but avoid sudden changes to your routine before testing to avoid misleading results.
  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