Prostate-Specific Antigen (PSA) with Free PSA Ratio and Differential Analysis (Screening)
This test measures prostate-specific antigen (PSA), a protein produced by the prostate gland, to help assess potential prostate health concerns.
["PSA screening may help detect early signs of prostate issues, including benign enlargement or cancer."]
Key facts at a glance
- LOINC
- 50781-4
- Short code
- CA19-9-PF
- Synonyms
- Cancer Ag19-9 Prt-aCnc
- Category
- chemistry
- Sample
- serum
- Container
- Sterile, leak-proof container; red-top tube or transfer to plain tube without anticoagulant preferred for immunoassay analysis
- Units
- N/A
- Ref low
- 19
- Ref high
- 9
- Critical range
- 0.5 N/A – —
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- ≥ 18 years
- Method
- Immunoassay (Chemiluminescent or Electrochemiluminescent)
- CPT
- 86316
- SNOMED
- 39579006
- Specimen volume
- 5-10 mL of peritoneal fluid
- Stability
- Refrigerated at 2-8°C for up to 7 days; frozen at -20°C or below for longer storage. Avoid repeated freeze-thaw cycles.
- Hemolysis max
- 500
- Lipemia max
- 1000
- Icterus max
- 500
- TAT
- 24–72 hours
- Order
- routine
What PSA Does in the Body
PSA is normally found in small amounts in the blood. When the prostate is healthy, it circulates freely. If the prostate is inflamed, irritated, or cancerous, PSA may be released into the blood at higher levels. This test evaluates both total PSA and free PSA to help determine the proportion of PSA that is unbound, which can provide additional insight into prostate health.
Why This Test Might Be Ordered
Your healthcare provider may recommend PSA screening if you have symptoms like frequent urination, difficulty urinating, pain in the pelvic area, or if you’re at higher risk due to age, family history, or other medical conditions. It’s also used as part of routine check-ups for men over a certain age.
What to Expect Before the Test
No special preparation is needed, but you may be asked to avoid ejaculation for 2–3 days before the test. Drink plenty of water the day of the test to help your urine flow smoothly. Avoid heavy exercise or strenuous activity for a day before testing.
What Happens During the Test
A small blood sample is drawn from a vein in your arm. This is a quick and painless procedure, similar to getting an injection. The sample is then sent to a lab for analysis.
Reference range
No established reference range for CA 19-9 in peritoneal fluid. Results should be interpreted in conjunction with serum CA 19-9 levels and clinical findings. Elevated levels may suggest peritoneal involvement by malignancy, particularly pancreatic, gastric, or colorectal cancer.N/A
No special preparation required. Specimen obtained via paracentesis (peritoneal fluid collection) as part of clinical workup.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
◆Associated findings1
Short name
PSA Screening
Frequently asked questions
What does a high PSA level mean?
How often should I get a PSA test?
Can lifestyle changes affect PSA levels?
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 17, 2026. · Read our editorial policy