PSA and Prostate Health Index (phi): Understanding the Types of PSA Test and Their Importance
Updated: Apr 24
Prostate-specific antigen (PSA) is a protein produced by the prostate gland, and its levels in the blood can be used as a marker for prostate health. PSA testing is commonly used to screen for prostate cancer and other prostate-related conditions. In this post, we'll go over the different types of PSA tests and explain why the combination of PSA and Prostate Health Index (phi) is becoming an increasingly important tool for prostate cancer detection.
Types of PSA Test
Total PSA Test
The total level of PSA in the blood. Elevated levels of PSA can indicate prostate inflammation, infection, or cancer.
Free PSA Test
The amount of PSA that is not bound to other proteins in the blood. This test can be helpful in distinguishing between benign prostate conditions and prostate cancer.
PSA Velocity Test
How quickly the PSA level is rising over time. Rapidly rising PSA levels can indicate the possibility of prostate cancer.
PSA Density Test
The level of PSA in relation to the size of the prostate gland. This test can help to determine the likelihood of prostate cancer, especially in men with larger prostates.
PSA Doubling Time Test
The amount of time it takes for the PSA level to double. This test can help to determine the rate of growth of the prostate cancer.
Prostate Health Index (phi) Test
This is a combination of three tests - total PSA, free PSA, and p2PSA - that are used to provide a more accurate assessment of prostate cancer risk. The phi test is particularly useful in distinguishing between benign prostate conditions and prostate cancer in men with borderline PSA levels.
PSA and phi: What Do They Mean?
PSA testing can be useful in detecting prostate cancer, but it is not a perfect test. Elevated PSA levels can occur for reasons other than cancer, and some men with prostate cancer may have low levels of PSA. Therefore, it is important to interpret PSA test results in the context of other factors, such as age, family history, and overall health. For example, the PSA level below 4.0 ng/mL is generally considered as normal for men under the age of 50. However, below 4.5 ng/mL is considered to be normal in the age range of 50 to 70.
The phi test provides a more accurate assessment of prostate cancer risk by combining different PSA tests with other clinical factors. In particular, the phi test measures p2PSA, which is a form of PSA that is more closely associated with prostate cancer than other forms of PSA. According to the guildeline from National Comprehensive Cancer Network (NCCN), the men with a phi score above 35 should be considered for biopsy and normal DRE.
PSA Biopsy and phi
If PSA levels are elevated, a biopsy may be performed to confirm or rule out the presence of prostate cancer. However, PSA biopsies can sometimes be inaccurate and miss some cases of prostate cancer. The phi test can be particularly helpful in guiding decisions about whether or not to undergo a biopsy, especially in men with borderline PSA levels.
Take away message
In conclusion, PSA testing is an important tool for detecting prostate cancer and other prostate-related conditions. However, not all PSA tests are created equal, and it is important to interpret PSA test results in the context of other factors. The Prostate Health Index (phi) is becoming an increasingly important tool for prostate cancer detection, as it provides a more accurate assessment of prostate cancer risk and can help to guide decisions about further testing and treatment. If you have concerns about your prostate health, talk to your doctor about the best screening options for you.
National Cancer Institute, Prostate-Specific Antigen (PSA) Test
NCCN Clinical Practice Guidelines in Oncology - Prostate Cancer Early Detection, 2019
Rapid quantitative immunoassay analyzer