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HelpTest ID: PHI11 Prostate Health Index Reflex, Serum
Specimen Required
Patient Preparation:
1. Specimens for testing should be collected prior to prostate manipulations such as digital rectal examination, prostatic massage, transrectal ultrasound, and prostatic biopsy.
2. A 6-week waiting period between needle biopsy and specimen collection is recommended.
3. Specimens should not be collected from patients receiving therapy with high biotin (vitamin B7) doses (ie, >5 mg/day) until at least 8 hours following the last biotin administration.
Supplies: Sarstedt Aliquot Tube 5 mL (T914)
Collection Container/Tube: Red top (serum gel/SST are not acceptable)
Submission Container/Tube: Plastic vial
Specimen Volume: 1 mL
Collection Instructions: Within 3 hours of collection, centrifuge, aliquot serum into a plastic vial, and refrigerate. Freeze sample within 24 hours of collection and send frozen.
Useful 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 and digital rectal examination findings that are not suspicious for cancer
Reflex Tests
| Test ID | Reporting Name | Available Separately | Always Performed |
|---|---|---|---|
| PHI13 | Prostate Health Index (phi) Reflex | No | No |
Testing Algorithm
This test begins with the analysis of prostate-specific antigen (PSA). If the PSA concentration is between 2.0 and 10.0 ng/mL, then the reflex test will be performed at an additional charge.
If the initial PSA concentration is between 2.0 and 10.0 ng/mL, then free PSA and [-2]pro-PSA isoform results will be reported.
If the initial PSA concentration is between 4.0 and 10.0 ng/mL, then the percent free PSA result and prostate health index (phi) will be calculated and reported.
If the initial PSA concentration is between 2.0 and 4.0 ng/mL, then the percent free PSA result and prostate health index (phi) will not be calculated or reported.
Method Name
Immunoenzymatic Assay
Reporting Name
Prostate Health Index Reflex, SSpecimen Type
Serum RedSpecimen Minimum Volume
0.75 mL
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Serum Red | Frozen (preferred) | 150 days | |
| Ambient | 24 hours | ||
| Refrigerated | 24 hours |
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. In conditions of increased glandular size and tissue damage, PSA is released into circulation. Measurement of serum PSA is useful for determining the extent of prostate cancer and assessing the response to prostate cancer treatment. PSA is also used as a screening tool for prostate cancer detection, although its use in screening has become controversial in recent years. While an elevated serum PSA is associated with prostate cancer, a number of benign conditions, such as benign prostatic hyperplasia and prostatitis might lead to elevated serum PSA concentrations. As a consequence, PSA lacks specificity for prostate cancer detection.
Several PSA isoforms have been identified that can further increase the specificity of PSA for prostate cancer. In particular, the [-2] form of proPSA (p2PSA) shows improved performance over either total or free PSA for prostate cancer detection on biopsy. The prostate health index (phi) is a formula that combines all 3 PSA forms (total PSA, free PSA, and p2PSA) into a single score. phi is calculated using the following formula: (p2PSA/free PSA) x square root of PSA.
In a multicenter study that compared the performance of total PSA, free PSA, p2PSA, and phi in men undergoing prostate biopsy due to a serum PSA concentration between 4.0 and 10.0 ng/mL, phi was the best predictor of any prostate cancer, high-grade cancer, and clinically significant cancer. At 95% clinical sensitivity, the clinical specificity of phi was 16.0%, compared to 8.4% for free PSA and 6.5% for total PSA.
Reference Values
Females: Not applicable
PROSTATE-SPECIFIC ANTIGEN (PSA) MALES:
|
Age |
Reference range |
|
<40 years |
≤2.0 ng/mL |
|
40-49 years |
≤2.5 ng/mL |
|
50-59 years |
≤3.5 ng/mL |
|
60-69 years |
≤4.5 ng/mL |
|
70-79 years |
≤6.5 ng/mL |
|
≥80 years |
≤7.2 ng/mL |
PERCENT FREE PSA MALES:
When PSA is in the range of 4.0-10.0 ng/mL
|
% Free PSA |
Probability of cancer |
|
≤10% |
56% |
|
11-15% |
28% |
|
16-20% |
20% |
|
21-25% |
16% |
|
>25% |
8% |
PROSTATE HEALTH INDEX (phi) MALES:
When PSA is in the range of 4.0-10.0 ng/mL
|
phi range |
Probability of cancer |
95% Confidence interval |
|
0-26.9 |
9.8% |
5.2-15.4% |
|
27.0-35.9 |
16.8% |
11.3-22.2% |
|
36.0-54.9 |
33.3% |
26.8-39.9% |
|
≥55.0 |
50.1% |
39.8-61.0% |
Interpretation
The prostate health index (phi) may be used to determine the probability of prostate cancer on biopsy in men aged 50 years and older with total prostate-specific antigen (PSA) in the 4.0 to 10.0 ng/mL range. Low phi scores are associated with a lower probability of finding prostate cancer on biopsy, and higher phi scores are associated with an increased probability of finding prostate cancer on biopsy. The choice of an appropriate phi score to be used in guiding clinical decision-making may vary for each patient and may depend on other clinical factors or family history. The table below indicates the probability of finding prostate cancer on biopsy when total PSA is in the range of 4.0 to 10.0 ng/mL and may be used as guidance for interpreting the phi score.
|
phi range |
Probability of cancer |
95% Confidence interval |
|
0-26.9 |
9.8% |
5.2%-15.4% |
|
27.0-35.9 |
16.8% |
11.3%-22.2% |
|
36.0-54.9 |
33.3% |
26.8%-39.9% |
|
55.0+ |
50.1% |
39.8%-61.0% |
Clinical Reference
1. Catalona WJ, Partin AW, Sanda MG, et al. A multicenter study of [-2]pro-prostate-specific antigen combined with prostate-specific antigen and free prostate-specific antigen for prostate cancer detection in the 2.0 to 10.0 ng/mL prostate-specific antigen range. J Urol. 2011;185(5):1650-1655
2. Pecoraro V, Roli L, Plebani M, Trenti T. Clinical utility of the (-2)proPSA and evaluation of the evidence: a systematic review. Clin Chem Lab Med. 2016;54(7):1123-1132. doi:10.1515/cclm-2015-0876
3. Loeb S, Catalona WJ: The Prostate Health Index: a new test for the detection of prostate cancer. Ther Adv Urol. 2014 Apr;6(2):74-77. doi: 10.1177/1756287213513488
Day(s) Performed
Monday through Saturday
Report Available
1 to 3 daysTest 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 - Total PSA
84154 - Free PSA (if appropriate)
86316 - [-2]ProPSA (if appropriate)
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| PHI11 | Prostate Health Index Reflex, S | 53764-7 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| PHI12 | Prostate Specific Antigen, S | 83112-3 |
Forms
If not ordering electronically, complete, print, and send an Oncology Test Request (T729) with the specimen.
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