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HelpTest Code PSAS Prostate-Specific Antigen (PSA) Screen, Serum
Additional Codes
| Mayo Test ID |
|---|
| SPSA |
Reporting Name
Prostate-Specific Ag Screen, SUseful For
As a screening aid in the detection of prostate cancer when used in conjunction with a digital rectal exam in men 50 years or older
Screening to aid in the prognosis and management of individuals diagnosed with prostate cancer
Method Name
Electrochemiluminescent Immunoassay
Performing Laboratory
Mayo Clinic Laboratories in Rochester
Specimen Type
SerumOrdering Guidance
Free prostate-specific antigen (PSA) can be added to previously-submitted PSA screen specimen within 72 hours of performing the total PSA. Specimen must have been shipped frozen.
If both free and total PSA results are desired, order PSAFT / Prostate-Specific Antigen (PSA), Total and Free, Serum.
Necessary Information
Include patient's age.
Specimen Required
Supplies: Starstedt Aliquot Tube 5mL (T914)
Collection Container/Tube:
Preferred: Serum gel
Acceptable: Red top
Submission Container/Tube: Plastic vial
Specimen Volume: 1 mL
Collection Instructions:
1. Red-top tube must be centrifuged, and the serum aliquoted into a plastic vial within 2 hours of collection.
2. Serum gel tube must be centrifuged within 2 hours of collection.
Specimen Minimum Volume
0.75 mL
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Serum | Frozen (preferred) | 180 days | |
| Refrigerated | 5 days |
Reject Due To
| Gross hemolysis | Reject |
| Gross lipemia | OK |
| Gross icterus | OK |
Reference Values
Males:
|
Age (years) |
PSA upper limit (ng/mL) |
|
<40 |
≤2.0 |
|
40-49 |
≤2.5 |
|
50-59 |
≤3.5 |
|
60-69 |
≤4.5 |
|
70-79 |
≤6.5 |
|
≥80 |
≤7.2 |
Females: Not applicable
Day(s) Performed
Monday through Saturday
CPT Code Information
84153
G0103 (if appropriate)
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| SPSA | Prostate-Specific Ag Screen, S | 83112-3 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| SPSA | Prostate-Specific Ag Screen, S | 83112-3 |
Clinical Information
Prostate-specific antigen (PSA) is a glycoprotein produced by the prostate gland, the lining of the urethra, and the bulbourethral gland. Normally, very little PSA is secreted in the blood. Increases in glandular size and tissue damage caused by benign prostatic hypertrophy, prostatitis, or prostate cancer may increase circulating PSA levels.
In patients with previously diagnosed prostate cancer, PSA testing is advocated as an early indicator of tumor recurrence and as an indicator of response to therapy. The role of PSA in early detection of prostate cancer is controversial. The American Cancer Society recommends annual examination with digital rectal examination and serum PSA beginning at age 50 and for men with a life expectancy of at least 10 years after detection of prostate cancer. For men in high-risk groups, such as African Americans or men with a first-degree relative diagnosed at a younger age, testing should begin at a younger age. It is generally recommended that information be provided to patients about the benefits and limitations of testing and treatment so they can make informed decisions.
Interpretation
Prostate-specific antigen (PSA) values are reported with the 95th percentile limits by decade of age. These reference limits include men with benign prostatic hyperplasia. They exclude all cases with proven cancer.
PSA values exceeding the age-specific limits are suspicious for prostate disease, but additional testing, such as prostate biopsy, is needed to diagnose prostate pathology.
The minimal reporting value is 0.1 ng/mL. Values above 0.2 ng/mL are considered evidence of biochemical recurrence of cancer in men after prostatectomy.
Cautions
Serum markers are not specific for malignancy, and values may vary by method.
When age is not supplied, the results cannot be flagged as high or low.
Digital rectal examination generally does not increase normal prostate-specific antigen (PSA) values. However, cystoscopy, urethral instrumentation, and prostate biopsy may increase PSA levels.
In rare cases, some individuals can develop antibodies to mouse or other animal antibodies (often referred to as human anti-mouse antibodies [HAMA] or heterophile antibodies), which may cause interference in some immunoassays. The presence of antibodies to streptavidin or ruthenium can also rarely occur and may interfere in this assay. Caution should be used in interpretation of results, and the laboratory should be alerted if the result does not correlate with the clinical presentation.
Serum biotin concentrations up to 1200 ng/mL do not interfere with this assay. Concentrations up to 1200 ng/mL may be present in specimens collected from patients taking extremely high doses of biotin up to 300 mg per day.(1) In a study among 54 healthy volunteers, supplementation with 20 mg/day biotin resulted in a maximum serum biotin concentration of 355 ng/mL 1 hour post-dose.(2)
Method Description
The Elecsys cobas Total PSA (prostate-specific antigen) assay is a sandwich electrochemiluminescence immunoassay that employs a biotinylated monoclonal PSA-specific antibody and a monoclonal PSA-specific antibody labeled with ruthenium complex. PSA in the specimen reacts with both the biotinylated monoclonal PSA-specific antibody (mouse) and the monoclonal PSA-specific antibody (mouse) labeled with a ruthenium, forming a sandwich complex. Streptavidin-coated microparticles are added, and the mixture aspirated into the measuring cell where the microparticles are magnetically captured onto the surface of the electrode. Unbound substances are then removed with ProCell. Application of voltage to the electrode induces the chemiluminescent emission, which is then measured against a calibration curve to determine the amount of PSA in the patient specimen. This method has been standardized against the Reference Standard/WHO 96/670.(Package insert: Elecsys total PSA reagent. Roche Diagnostics; V 2.0, 06/2023)