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

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 mainly by the prostate gland, which can help detect or monitor prostate health.

Quick summary

["PSA levels may indicate prostate issues, including benign enlargement or cancer."]

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

Key facts at a glance

LOINC
105803-1
Short code
S pyo DNA Ct Bld Pos Qn NAA+probe
Synonyms
S pyo DNA Ct Bld Pos Qn NAA+probe
Category
coagulation
Sample
whole-blood
Container
Lavender-top (EDTA)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
probe-amp-tar
Specimen volume
3 mL
Stability
Room temperature: 4h, Refrigerated: 24h
Hemolysis max
0
Lipemia max
0
Icterus max
0
TAT
4–24 hours
Order
routine

Why This Test Is Done

Your doctor may order a PSA test to check for prostate problems, such as an enlarged prostate (benign prostatic hyperplasia), prostate infection, or prostate cancer. It can also be used to monitor treatment progress or screen for early signs of prostate issues in certain cases.

What to Expect Before the Test

No special preparation is needed for this blood test. You may have a small needle inserted into your arm to draw blood. If you’re concerned about discomfort, let your healthcare provider know.

What the Results Mean

PSA levels alone don’t diagnose prostate cancer—they’re often used alongside other tests and clinical findings. Higher-than-normal levels may signal potential issues, but they can also be influenced by factors like age, recent ejaculation, or prostate inflammation.

Common Causes of Abnormal Results

Elevated PSA levels can result from conditions like prostate infection, inflammation, or benign enlargement. Lower-than-normal levels may suggest an underactive prostate or certain medications. Always discuss results with your doctor.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

PSA Blood Test

Frequently asked questions

How often will I need this test?
Your doctor will determine how often you need retests based on your symptoms, medical history, and test results. Some patients may have PSA tests every few months or years, while others may need more frequent checks.
What if my PSA level is in the normal range but I still have symptoms?
A normal PSA level doesn’t rule out prostate issues. Symptoms like urinary changes or pain may prompt further testing, such as a digital rectal exam or additional imaging.
Can diet or medications affect PSA results?
Certain foods (e.g., cruciferous vegetables) or medications (e.g., finasteride) may influence PSA levels. Always inform your doctor about all medications or supplements you take before the test.
  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