Prostate Specific Antigen (PSA), Total with Reflex to Free
Test ID: A861
Prostate specific antigen (PSA) is a serine protease glycoprotein, which is predominantly produced in the prostate. Blood levels of PSA are a useful indicator of prostatic pathology, to evaluate men at risk of prostate cancer, and for assessment after treatment.
How to order a test
- PSA Ratio
What is Included?
Measurement of total and free PSA in a blood sample by chemiluminescent microparticle immunoassays.
1 – 3 business days
The turnaround time is not guaranteed. The average turnaround time is 1 – 3 business days from the date that the sample arrives at the laboratory. Shipping time for the sample is not included. Additional time is required if the case requires confirmatory or reflex testing, or if the sample is insufficient, or if a recollection is required.
Additional Information and Resources
Preparation Before Specimen Collection
50 μL in a microtainer
Microtainer (regular blood tube)
This test requires a blood sample from a finger prick. All supplies for sample collection are provided in the kit.
- First wash and dry hands. Warm hands aid in blood collection.
- Clean the finger prick site with the alcohol swab and allow to air dry.
- Use the provided lancet to puncture the skin in one quick, continuous and deliberate stroke.
- Wipe away the first drop of blood.
- Massage hand and finger to increase blood flow to the puncture site. Angle arm and hand downwards to facilitate blood collection on the fingertip.
- Drip blood into the microtainer tube.
- Dispose of all sharps safely and return sample to the laboratory in the provided prepaid return shipping envelope.
NOTES: Avoid squeezing or ‘milking’ the finger excessively. If more blood is required and blood flow stops, perform a second skin puncture on another finger. Do not touch the fingertip.
Maintain specimen at temperatures between 2°C and 30°C during storage and transport.
Blood samples can be refrigerated or kept at room temperature for up to 7 days.
Causes for Rejection
- Incorrect or incomplete patient identification
- Incorrect specimen collection
- Inappropriate storage and transport conditions
- Incorrect specimen volume
To measure total and free PSA levels in a blood sample and calculate the PSA ratio, to aid in the diagnosis of prostate abnormalities, particularly prostate cancer.
- This report is not intended for use in medico-legal applications.
- These results should be interpreted in conjunction with other laboratory and clinical information.
- Correct specimen collection and handling is required for optimal assay performance.
- False results may occur in specimens from individuals that have received preparations of mouse monoclonal antibodies for diagnosis or therapy. Additional clinical or diagnostic information may be required for these specimens.
- Hormonal therapy may affect PSA expression.
- Digital rectal examination, prostatic massage, ultrasonography, needle biopsy, and ejaculation may cause clinically significant PSA increases. Blood for PSA analyses should be collected prior to prostatic manipulations.
- Total and free PSA values determined with assays from different manufacturers can vary due to differences in assay methods and reagent specificity. Values obtained with different assay methods cannot be used interchangeably during patient monitoring.
Chemiluminescent microparticle immunoassays (Alinity i Total PSA and Alinity i Free PSA assays)
Total PSA: ≤ 4.0 ng/mL
Free PSA: ≤ 0.5 ng/mL
The PSA ratio (% Free PSA) provides a probability of prostate cancer for men with non-suspicious DRE results and total PSA levels between 4 and 10 ng/mL:
|% Free PSA||50 – 64 years||65 – 74 years|
|0.00 – 10.00||56%||55%|
|10.01 – 15.00||24%||35%|
|15.01 – 20.00||17%||23%|
|20.01 – 25.00||10%||20%|
These probabilities were obtained from Catalona WJ, et al. Use of the percentage of free prostate-specific antigen to enhance differentiation of prostate cancer from benign prostatic disease: a prospective multicenter clinical trial. JAMA. 1998 May 20;279(19):1542-7.