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HelpTest Code FPSA PSA Free
EHR Test Codes
| Test Code | Test Name | |
| Atlas | ||
| Cerner | PSA Free |
Specimen Requirements
Preparation of Patient:
None
Container Type:
Gold Top SST Gel & Clot Activator Tube
Specimen Type:
Serum
Specimen Volume:
1.0 mL of Serum minimum .5 mL of Serum
Specimen Handling/Transport:
Separate serum from cells within 2 hours of collection.
Transport refrigerated 2-8°C
Specimen Stability/Storage:
1 day refrigerated 2-8°C
>1 day frozen -20°C
Performing Laboratory
Munson Medical Center Laboratories
Chemistry Department
Priority, Frequency, & Turnaround
Priority:
Non-Emergent
Frequency:
24 hours 7 days a week
Turnaround:
0 - 1 days
Methodology
Chemiluminescent Immunoassay
Reporting
Reference Range:
None available for PSA Free
Testing performed by chemiluminescence on a Beckman Coulter DXI/Access platform. Results may not be comparable with tests performed on other manufacturer's methods or platforms.
Interpretation:
Free PSA is reported as a percentage of Total PSA, the following reference ranges apply to this ratio:
About 25% of asymptomatic men older than 50 years and PSA values of 4 - 10 ng/mL have prostate cancer, compared with about 12% for those with PSA values of 2.0 to 3.0 ng/mL. Free PSA can help classify these men into subgroups with higher or lower cancer rates:
| Free/Total Ratio | Cancer Rate | |
| PSA 4 - 10 ng/mL | <0.10 | >40% |
| >0.25 | <10% | |
| PSA 2.0 - 3.9 ng/mL | <0.10 | >30% |
| >0.18 | <10% | |
| PSA < 2.0 ng/mL not calculated, comment RNCC (ratio not calculated becuase clinical usefulness is not defined except in the range of total PSA 2 - 10 ng/mL is resulted. | ||
Critical Decision:
None
Clinical Significance
Prostate cancer is the most common type of cancer found in men in the United States, with an incidence of approximately one case for every ten men. It is also the second leading cause of cancer deaths among American men.
Prostate-specific antigen was identified and purified by Wang and co-workers in 1979. PSA, a serine protease, is produced by the epithelial cells of the prostate, and is produced by both benign and malignant cells. Abnormalities in the prostate gland architecture resulting from trauma or disease can lead to "leakage" of PSA into the bloodstream.
PSA exists primarily as three forms in serum. One form of PSA is believed to be enveloped by the protease inhibitor, alpha-2 macroglobulin and has been shown to lack immunoreactivity. A second form is complexed to another protease inhibitor, alpha-1 antichymotrypsin (ACT). The third form of PSA is not complexed to a protease inhibitor, and is termed free PSA. The latter two forms are immunologically detectable in commercially available PSA assays and are referred to collectively as total PSA.
Previous reports have shown that measurement of PSA forms is useful in the differentiation of prostate cancer from benign prostatic conditions. In patients with elevated PSA concentrations, men with prostate cancer tend to have lower percent free PSA (free PSA/total PSA) values than men with benign disease. This difference in the distribution of percent free PSA values in men with and without cancer may be used to select cutoffs for biopsy decisions, maintaining 90% to 95% sensitivity, while sparing 20% to 30% of men with benign disease from biopsy. Percent free PSA may also be used for risk assessment, to determine the probability of cancer for an individual patient. Lower percent free PSA values are associated with higher risk of cancer.
Percent free PSA values should not be interpreted as definitive evidence for the presence or absence of prostate cancer. Prostatic biopsy is required for diagnosis of cancer.
CPT Code
84154