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Prostate-Specific Antigen (PSA) in Serum

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

This test measures the level of prostate-specific antigen, a protein produced by the prostate gland, often used to screen for or monitor prostate health.

Quick summary

["PSA levels help assess prostate health and detect potential issues like benign prostatic hyperplasia or prostate cancer."]

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

Key facts at a glance

LOINC
33310-4
Short code
PS Ab Ser Ql
Synonyms
PS Ab Ser Ql
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Ref low
0
Ref high
4
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
CPT
84153
SNOMED
39392002
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 Is This Test Done?

Doctors may order a PSA test to check for prostate problems, such as an enlarged prostate, infections, or cancer. It can also be used during follow-up for patients already diagnosed with prostate issues.

What Does a High PSA Level Indicate?

Elevated PSA levels may suggest conditions like an enlarged prostate, prostate infection, or inflammation. However, other factors, such as age, race, or recent ejaculation, can also affect PSA levels.

What Does a Low PSA Level Indicate?

Low PSA levels are less commonly concerning but may occur in younger men or those with certain medical conditions. They can also be influenced by medications or other health factors.

How Is This Test Performed?

A blood sample is drawn from a vein in your arm. The blood is then sent to a lab for analysis. You may experience a slight pinch or discomfort during the draw, but it usually takes a few minutes to complete.

Reference range

Normal: <4.0 ng/mLN/A

Specimen: serum

No special preparation required. For PSA, avoid sexual activity for 24-48 hours before the test.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance: PSA Levels and Prostate Health

Short name

PSA Serum

Frequently asked questions

What Are Common Causes of Fluctuating PSA Levels?
PSA levels can vary due to factors like recent ejaculation, exercise, prostate massage, or certain medications. It’s important to discuss these with your healthcare provider if they affect your test results.
How Often Should I Get This Test?
Your doctor will determine the frequency of PSA testing based on your health history, age, and symptoms. Regular screenings may be recommended for men at higher risk or those with a family history of prostate cancer.
What If My PSA Level Is Abnormal?
If your PSA level is elevated, further tests may be needed to investigate the cause, such as additional imaging or a biopsy. Your doctor will guide you on the next steps based on your individual situation.
  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