Assessing the risk of prostate cancer in patients with borderline or moderately increased total PSA (4.0-10.0 ng/mL)
Determining which patients should have follow-up prostate biopsy
In individuals with a total prostate-specific antigen (PSA) concentration between 4.0 and 10.0 ng/mL, free PSA:total PSA ratio could help determine the relative risk of prostate cancer. The lower the free PSA:total PSA ratio, the higher the risk of prostate cancer.
Electrochemiluminescent Immunoassay (ECLIA)
Free PSA
PSA (Prostate-Specific Antigen)
PSA Free/Total Ratio
PSA Total and Free
PSA Ratio
Serum
This test should be ordered only in patients with a total prostate-specific antigen concentration between 4 and 10 ng/mL.
Include patient's age.
Supplies: Sarstedt 5 mL Aliquot Tube (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.
If not ordering electronically, complete, print, and send 1 of the following forms with the specimen:
-General Request (T239)
-Oncology Test Request (T729)
0.75 mL
Gross hemolysis | Reject |
Gross lipemia | OK |
Gross icterus | Reject |
Specimen Type | Temperature | Time | Special Container |
---|---|---|---|
Serum | Frozen (preferred) | 90 days | |
Refrigerated | 72 hours |
Assessing the risk of prostate cancer in patients with borderline or moderately increased total PSA (4.0-10.0 ng/mL)
Determining which patients should have follow-up prostate biopsy
Prostate-specific antigen (PSA) is a glycoprotein that is produced by the prostate gland, the
PSA exists in serum in multiple forms: complexed to alpha-1-anti-
Higher total PSA levels and lower percentages of free PSA are
Most prostate cancers are slow growing, so the utility of prostate cancer screening is marginal in most men with a life expectancy of less than 10 years.
TOTAL PROSTATE-SPECIFIC ANTIGEN (PSA)
Males:
Age (years) | PSA upper limit (ng/mL) |
<40 | < or =2.0 |
40-49 | < or =2.5 |
50-59 | < or =3.5 |
60-69 | < or =4.5 |
70-79 | < or =6.5 |
> or =80 | < or =7.2 |
Females: Not applicable
FREE PSA:TOTAL PSA
Males:
When Total PSA concentration is in the range of 4.0-10.0 ng/mL:
Probability of cancer | |||
Free PSA/total PSA ratio | 50-59 years | 60-69 years | > or =70 years |
< or =0.10 | 49% | 58% | 65% |
0.11-0.18 | 27% | 34% | 41% |
0.19-0.25 | 18% | 24% | 30% |
>0.25 | 9% | 12% | 16% |
Females: Not applicable
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 |
< or =0.10 | 49% | 58% | 65% |
0.11-0.18 | 27% | 34% | 41% |
0.19-0.25 | 18% | 24% | 30% |
>0.25 | 9% | 12% | 16% |
Normal results do not eliminate the possibility of prostate cancer.
Values obtained with different assay methods or kits may be different and cannot be used interchangeably.
Tumor markers are not specific for malignancy. Test results cannot be interpreted as absolute evidence for the presence or absence of malignant disease.
Specimens collected from patients undergoing prostate manipulation, especially needle biopsy and transurethral resection, may show erroneously high prostate-specific antigen (PSA) results. Care should be taken that specimens are obtained before these procedures are performed.
Prostate cancer patients receiving treatment with antiandrogens and luteinizing hormone-releasing factor agonists may exhibit markedly decreased levels of PSA. Also, men treated for benign prostatic hyperplasia with inhibitors of 5-alpha-reductase (finasteride) may demonstrate a significant reduction in PSA levels compared to values before treatment. Care should be taken in interpreting values for these individuals.
In rare cases, interference due to extremely high titers of antibodies to ruthenium or streptavidin can occur.
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)
1. Peyro Saint Paul, 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. Catalona WJ, Smith DS, Wolfert RL, Wang TJ, Rittenhouse HG, Ratliff TL, Nadler RB: Evaluation of percentage of free serum prostate-specific antigen to improve specificity of prostate cancer screening. JAMA. 1995 Oct:274(15);214-1220
3. 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
4. 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
5. Catalona WJ: Prostate cancer screening. Med Clin North Am. 2018 Mar;102(2):199-214. doi: 10.1016/j.mcna.2017.11.001
Total prostate-specific antigen:
The Roche Elecsys total prostate-specific antigen (PSA) assay is a sandwich electrochemiluminescent 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 is 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., Roche Diagnostics; V 1.0, 07/2018)
Free PSA:
The Roche Elecsys free PSA assay is a sandwich electrochemiluminescent immunoassay that employs a biotinylated monoclonal PSA-specific antibody and a monoclonal PSA-specific antibody labeled with ruthenium complex. Free 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 is 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 free PSA in the patient specimen. This method has been standardized against the Reference Standard/WHO 96/668.(Package insert: Elecsys Free PSA reagent, Roche Diagnostics; V 2.0, 10/2018)
The free PSA concentration is divided by the total PSA to derive the free:total ratio. The PSA, total and free test provides a free PSA measurement on every specimen, however, because very high or low total PSA measurements are predictive in themselves, a ratio is provided only when the total PSA is in the range of 4.0 to 10.0 ng/mL.
Monday through Friday
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.
84153
84154
Test Id | Test Order Name | Order LOINC Value |
---|---|---|
PSAFT | PSA Total and Free, S | 53764-7 |
Result Id | Test Result Name |
Result LOINC Value
Applies only to results expressed in units of measure originally reported by the performing laboratory. These values do not apply to results that are converted to other units of measure.
|
---|---|---|
TPSA | Total PSA | 83112-3 |
FPSA | Free PSA | 83113-1 |
PSA_R | Free PSA/PSA Ratio | 12841-3 |
Change Type | Effective Date |
---|---|
Test Changes - Specimen Information | 2021-09-22 |