Results of PSA tests are reported as nanograms of PSA per milliliter of blood (ng/mL). There's no specific cutoff point between a normal and abnormal PSA level. Your doctor might recommend a prostate biopsy based on results of your PSA test.
Variations of the PSA test
Your doctor might use other ways of interpreting PSA results before deciding whether to order a biopsy to test for cancerous tissue. These other methods are intended to improve the accuracy of the PSA test as a screening tool.
Researchers continue to investigate variations of the PSA test to determine whether they provide a measurable benefit.
Variations of the PSA test include:
- PSA velocity. PSA velocity is the change in PSA levels over time. A rapid rise in PSA may indicate the presence of cancer or an aggressive form of cancer. However, recent studies have cast doubt on the value of PSA velocity in predicting a finding of prostate cancer from biopsy.
- Percentage of free PSA. PSA circulates in the blood in two forms — either attached to certain blood proteins or unattached (free). If you have a high PSA level but a low percentage of free PSA, it may be more likely that you have prostate cancer.
- PSA density. Prostate cancers can produce more PSA per volume of tissue than benign prostate conditions can. PSA density measurements adjust PSA values for prostate volume. Measuring PSA density generally requires an MRI or transrectal ultrasound.
Talk to your doctor
Before getting a PSA test, talk to your doctor about the benefits and risks. If you decide that a PSA test is right for you, ask your doctor:
- When you will discuss the results
- What kinds of recommendations he or she might make if the results are positive
- How often you should repeat the test if the results are negative
Discussing these issues beforehand may make it easier for you to learn the results of your test and make appropriate decisions afterward.