What is a free prostate specific antigen test?
Free prostate-specific antigen (PSA) tests are laboratory blood tests that help detect signs of prostate cancer. Prostate-specific antigen is a substance produced by the prostate gland. Levels may vary based on a person’s age and other factors. There are two types of PSA measurements: the free PSA and the total PSA.
What is the difference between total and free PSA?
PSA is a protein produced in the prostate gland and the urinary system. PSA circulates through the body either on its own or bound to other proteins. The total PSA test is a measurement of the total amount of PSA. The free PSA only measures the portion of PSA circulating freely in the bloodstream and not bound to other proteins. By comparing the levels, your healthcare provider will determine the risk of prostate cancer.
Is free PSA good or bad?
Free PSA is neither good nor bad, but an alteration in the free PSA reading may indicate a risk of prostate cancer and a need for further testing. Your healthcare provider will look at the ratio of free to total PSA in determining risk for prostate cancer. A higher ratio of free to total PSA indicates lower risk, while a low ratio indicates a higher risk of prostate cancer. PSA levels alone can not confirm the diagnosis, so your healthcare provider will recommend further testing.
The PSA levels may be altered by other factors. Some of these include:
- Enlarged prostate gland
- Anal sex
- Prostate stimulation during a rectal examination
- Ejaculation
- Certain medications
- Exercise
- Urinary tract or bladder infections
- Prostate infection or prostatitis
What is a normal free PSA score?
The free PSA score is reported as a percentage. A normal level is 25% or higher. Healthcare providers may recommend a prostate biopsy for men whose percent-free PSA is between 10-25% and definitely if 10% or less.
What is a bad free PSA level?
Free PSA levels between 10-25% indicate a risk of prostate cancer, and levels of 10% or less are even more concerning. If your free PSA falls into this range, your healthcare provider may recommend a prostate biopsy.
How do you calculate free PSA ratio?
To calculate the free PSA ratio, the free PSA is divided by the total PSA and multiplied by 100. This ratio helps determine if there is cancer risk vs. enlargement of the prostate. The following chart indicates the risk of cancer-based on the free PSA ratio.
|
Free PSA Ratio
|
Probability of Cancer
|
|
0-10
|
56%
|
|
10-15
|
28%
|
|
15-20
|
20%
|
|
20-25
|
16%
|
|
>25
|
8%
|
How can I check my prostate health at home?
Prostate problems are not uncommon as men age. Benign prostatic hyperplasia or BPH is an enlargement of the prostate that is not caused by cancer. However, BPH can cause symptoms that are bothersome and can be treated by your healthcare provider. At home, PSA blood tests are available, but there are no other ways to check for prostate cancer at home.
To maintain prostate health, follow a healthy diet and lifestyle and notify your healthcare provider of any symptoms that may indicate a prostate problem. These may include:
- Frequent urination
- Urination several times through the night
- Blood in urine or semen
- Pain or burning during urination
- Painful ejaculation
- Frequent pain or stiffness in the lower back, hips, pelvis, rectum, or upper thighs
- Dribbling of urine
