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Prostate-Specific Antigen (PSA) in Serum by Immunoassay

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

This test measures the level of prostate-specific antigen (PSA), a protein produced mainly by the prostate gland. It helps evaluate prostate health and may assist in detecting prostate cancer or other prostate-related conditions.

Quick summary

["PSA levels can help guide discussions about prostate health, especially for men at higher risk."]

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

Key facts at a glance

LOINC
103627-6
Short code
S pyo DNA Spec Ql NAA+probe
Synonyms
S pyo DNA Spec Ql NAA+probe
Category
coagulation
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 Is This Test Done?

Your doctor may order this test to monitor symptoms of prostate issues, such as urinary problems, pain, or changes in bowel habits. It can also be used during screenings for prostate cancer, especially in men with a family history or those at higher risk. Sometimes, PSA levels are checked after treatment to see if the prostate is healing or if cancer has returned.

What to Expect Before the Test

No special preparation is needed for this blood test. You may be asked to fast for 8–12 hours before the draw, but your doctor will let you know if that applies. Avoid ejaculation for 2–3 days before the test if you’re being monitored for prostate health.

What Happens During the Test?

A healthcare provider will draw blood from a vein in your arm. The process is quick and usually causes only mild discomfort. The blood sample is then sent to a lab for analysis using an immunoassay method to detect PSA levels.

What Are Common Results and What Do They Mean?

PSA levels vary widely among individuals and can change with age, health conditions, or medications. A single test result doesn’t diagnose prostate cancer on its own—it’s often used alongside other tests and clinical findings. Your doctor will interpret results in the context of your overall health and symptoms.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance: PSA Levels and Prostate Health

Short name

PSA Blood Test

Frequently asked questions

What factors might affect PSA levels?
Several factors can influence PSA levels, including age (PSA levels naturally rise with age), prostate inflammation (prostatitis), benign prostatic hyperplasia (BPH), recent ejaculation, prostate surgery, or radiation therapy. High PSA levels can also be linked to prostate cancer, but they’re not definitive proof. Regular monitoring and follow-up with your doctor are key.
How often should PSA testing be done?
The frequency of PSA testing depends on your age, risk factors, and overall health. The U.S. Preventive Services Task Force recommends against routine PSA screening for men under 55, but discussions about testing should be personalized with your doctor. Men at higher risk (e.g., family history of prostate cancer) may be advised to start earlier or more frequently.
Can PSA levels be affected by medications?
Yes, certain medications—such as finasteride (Propecia) or dutasteride (Avodart)—can lower PSA levels. If you’re taking these or other prostate-related medications, let your doctor know, as this may impact test results.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

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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