Prostate-Specific Antigen (PSA) with Free PSA Ratio and Total PSA Probe Measurement
This test measures prostate-specific antigen (PSA) levels in your blood, including the ratio of free PSA to total PSA, which helps assess prostate health and potential concerns like benign prostatic hyperplasia (BPH) or early prostate cancer.
["PSA testing helps guide discussions about prostate health, but results alone don’t diagnose conditions—results are interpreted by your healthcare provider."]
Key facts at a glance
- LOINC
- 88247-2
- Short code
- NDMG
- Synonyms
- blaNDM Bld Pos Ql Probe
- Category
- chemistry
- Sample
- whole-blood
- Container
- Positive blood culture bottle (aerobic or anaerobic) submitted in its original container
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- probe
- CPT
- 87641
- SNOMED
- 122448007
- Specimen volume
- Not applicable; testing is performed directly from signal-positive blood culture broth
- Stability
- Blood culture bottles should be tested as soon as flagged positive by the continuous monitoring blood culture system. If testing is delayed, specimens should be processed within 24-48 hours of positivity while stored at room temperature (15-25°C) or refrigerated (2-8°C). Refer to specific assay manufacturer guidelines.
- Hemolysis max
- 0
- Lipemia max
- 0
- Icterus max
- 0
- TAT
- 1–4 hours
- Order
- routine
Why This Test Is Done
Your doctor may order this test to monitor symptoms of an enlarged prostate, screen for prostate cancer, or evaluate changes in PSA levels over time. Free PSA is a key part of the test because it can help distinguish between benign conditions and early cancer.
What to Expect Before the Test
No special preparation is needed, but avoid ejaculation for 2–3 days before testing if possible. Blood is drawn from a vein, usually in your arm, and the process takes about 15 minutes.
What the Test Measures
Total PSA measures all PSA in your blood, while free PSA measures only the unbound (active) form. The ratio of free PSA to total PSA can help assess prostate health, as cancerous tissues tend to produce less free PSA.
How Results Are Interpreted
Results are not interpreted alone—they’re reviewed alongside your symptoms, medical history, and other tests. A higher total PSA may raise concerns, but a normal PSA doesn’t rule out prostate issues. Free PSA ratio can help clarify whether further testing is needed.
Reference range
Negative for blaNDM gene (carbapenem resistance not detected)N/A
No special patient preparation required. Testing is performed on an existing positive blood culture specimen; no additional venipuncture is necessary for this assay.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Clinical Significance
Short name
PSA Profile (with Free PSA Ratio)
Frequently asked questions
What does a high PSA level mean?
Why is free PSA important?
How often should PSA testing be repeated?
Sources
- 1
- 2Lab Tests OnlineSource
- 3
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.
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