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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 both healthy and diseased prostate cells. It helps assess prostate health and detect potential issues like benign prostatic hyperplasia (BPH) or prostate cancer.

Quick summary

["PSA levels can guide discussions about prostate health and next steps in medical evaluation."]

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

Key facts at a glance

LOINC
59230-3
Short code
PSA CSF-mCnc
Synonyms
PSA CSF-mCnc
Category
chemistry
Sample
csf
Container
Sterile tube
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
1-2 mL
Stability
Immediate analysis required, Refrigerated: 1h
Hemolysis max
200
TAT
4–24 hours
Order
routine

Why Is This Test Done?

Doctors may order a PSA test to monitor prostate health, especially in men at higher risk of prostate cancer. It can also help evaluate symptoms like urinary changes or pain in the pelvic area. However, PSA alone is not definitive for cancer diagnosis—additional tests and clinical evaluation are needed.

What to Expect Before the Test

No special preparation is needed, but avoid ejaculation for 2–4 days before the test. If you’re taking medications that affect PSA levels (like finasteride or dutasteride), inform your healthcare provider.

What Happens During the Test?

A blood sample is drawn from a vein, usually in your arm. The process takes a few minutes, and you may feel a brief pinch. The sample is sent to a lab for analysis.

What Are Possible Results?

Results are reported in nanograms per milliliter (ng/mL). A low PSA level may suggest a healthy prostate, while elevated levels can signal potential issues, but interpretation depends on age, overall health, and other factors.

Reference range

Normal: <4.0 ng/mLN/A

Specimen: csf

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 Level

Frequently asked questions

What Does a High PSA Level Mean?
A high PSA level can indicate prostate inflammation, infection, BPH, or prostate cancer. However, many men with normal PSA levels still have prostate cancer, and some with cancer have normal levels. Your doctor will consider your symptoms, medical history, and other tests to guide further evaluation.
What Does a Low PSA Level Mean?
A low PSA level is less concerning but doesn’t rule out prostate issues entirely. It may suggest a smaller prostate, certain medications, or other factors. Your doctor will assess this in the context of your overall health.
Can PSA Levels Change Over Time?
Yes, PSA levels can fluctuate due to age, prostate size, infections, medications, or even physical activity. Regular monitoring may be needed if you have a history of prostate problems or are at higher risk.
  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