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HelpTest Code PSAFT Prostate-Specific Antigen (PSA), Total and Free, Serum
Reporting Name
PSA Total and Free, SUseful For
As an aid in distinguishing prostate cancer from benign prostatic conditions in men aged 50 years and older with total PSA between 4.0 and 10.0 ng/mL with digital rectal examination findings that are not suspicious for cancer
Performing Laboratory
Mayo Clinic Laboratories in Rochester
Specimen Type
SerumOrdering Guidance
This test may be ordered for patients undergoing evaluation of suspicion of prostate cancer, or for assessing the risk of prostate cancer in patients with borderline or moderately increased total prostate-specific antigen (4.0-10.0 ng/mL).
Necessary Information
Include patient's age.
Specimen Required
Supplies: Sarstedt Aliquot Tube 5 mL (T914)
Collection Container/Tube:
Preferred: Serum gel
Acceptable: Red top
Submission Container/Tube: Plastic vial
Specimen Volume: 1 mL
Collection Instructions: Centrifuge and aliquot serum into a plastic vial within 3 hours of collection.
Specimen Minimum Volume
0.75 mL
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Serum | Frozen (preferred) | 90 days | |
| Refrigerated | 72 hours |
Day(s) Performed
Monday through Saturday
Test Classification
This test has been cleared, approved, or is exempt by the US Food and Drug Administration and is used per manufacturer's instructions. Performance characteristics were verified by Mayo Clinic in a manner consistent with CLIA requirements.CPT Code Information
84153
84154
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| PSAFT | PSA Total and Free, S | 53764-7 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| TPSA | Total PSA | 83112-3 |
| FPSA | Free PSA | 83113-1 |
| PSA_R | Free PSA/PSA Ratio | 12841-3 |
Interpretation
When total prostate-specific antigen (PSA) concentration is below 2.0 ng/mL, the probability of prostate cancer in asymptomatic men is low, further testing and free PSA may provide little additional information. When total PSA concentration is above 10.0 ng/mL, the probability of cancer is high and prostate biopsy is generally recommended.
The total PSA range of 4.0 to 10.0 ng/mL has been described as a diagnostic "gray zone," in which the free PSA:total PSA ratio helps to determine the relative risk of prostate cancer (see table). Therefore, some urologists recommend using the free PSA:total ratio to help select which men should undergo biopsy. However, even a negative result of prostate biopsy does not rule-out prostate cancer. Up to 20% of men with negative biopsy results have subsequently been found to have cancer.
Based on free PSA:total PSA ratio: the percent probability of finding prostate cancer on a needle biopsy by age in years:
|
Free PSA:total PSA ratio |
50-59 years |
60-69 years |
70 years and older |
|
≤0.10 |
49% |
58% |
65% |
|
0.11-0.18 |
27% |
34% |
41% |
|
0.19-0.25 |
18% |
24% |
30% |
|
>0.25 |
9% |
12% |
16% |
Clinical Reference
1. Saint Paul LP, Debruyne D, Bernard D, Mock DM, Defer GL. Pharmacokinetics and pharmacodynamics of MD1003 (high-dose biotin) in the treatment of progressive multiple sclerosis. Expert Opin Drug Metab Toxicol. 2016;12(3):327-344. doi:10.1517/17425255.2016.1136288
2. Grimsey P, Frey N, Bendig G, et al. Population pharmacokinetics of exogenous biotin and the relationship between biotin serum levels and in vitro immunoassay interference. Int J Pharmacokinet. 2017 Sept;2(4):247-256. doi:10.4155/ipk-2017-00131.
3. Catalona WJ, Smith DS, Wolfert RL, et al. Evaluation of percentage of free serum prostate-specific antigen to improve specificity of prostate cancer screening. JAMA. Oct:274(15);214-1220
4. Oesterling JE, Jacobsen SJ, Klee GG, et al. Free, complexed and total serum prostate specific antigen: the establishment of appropriate reference ranges for their concentrations and ratios. J Urol. 1995 Sep;154(3):1090-1095. doi:10.1016/s0022-5347(01)66984-2
5. Duffy MJ. Biomarkers for prostate cancer: prostate-specific antigen and beyond. Clin Chem Lab Med. 2020 Feb 25;58(3):326-339. doi: 10.1515/cclm-2019-0693
6. Catalona WJ: Prostate cancer screening. Med Clin North Am. 2018 Mar;102(2):199-214. doi:10.1016/j.mcna.2017.11.001
7. Catalona WJ, Smith DS, Wolfert RL, et al. Evaluation of percentage of free serum prostate-specific antigen to improve specificity of prostate cancer screening. JAMA. 1995:274(15);214-1220
8. Ilic D, Djulbegovic M, Jung JH, et al. Prostate cancer screening with prostate-specific antigen (PSA) test: a systematic review and meta-analysis. BMJ. 2018;362:k3519. doi:10.1136/bmj.k3519
Report Available
1 to 3 daysMethod Name
Electrochemiluminescent Immunoassay (ECLIA)
Forms
If not ordering electronically, complete, print, and send 1 of the following forms with the specimen:
-General Request (T239)
-Oncology Test Request (T729)
Testing Algorithm
Total prostate-specific antigen (PSA) and free PSA are performed and reported on every specimen.
If the initial total PSA concentration is between 4.0 and 10.0 ng/mL, then the percent free PSA result will be calculated and reported.