- Prostate Cancer Slideshow Pictures
- Medical Illustrations of the Prostate Image Collection
- Men's Screening Tests Slideshow
- Patient Comments: PSA Test - Patient Experience
- Prostate-specific antigen (PSA) test facts
- What is a PSA blood test?
- How is PSA test measured?
- What causes PSA elevation in the blood?
- What can lower the PSA test result?
- What is the accuracy of the PSA test?
- What are normal results for the PSA test?
- What are age-specific reference ranges for serum PSA?
- How is PSA used for early detection of prostate cancer?
- What is the cost of the PSA test?
- What is the free PSA test?
- What is free/total PSA ratio?
- What is PSA velocity and PSA doubling time?
- How is PSA testing used for pretreatment staging of prostate cancer?
- How is PSA testing used in the management of prostate cancer after treatment?
- What are the limitations of the PSA test?
- What is digital rectal examination (DRE)?
- What is the PSA screening controversy?
- How should the PSA test be used for the early detection of prostate cancer?
- What is PCA3?
- What is the 4K biomarker?
Quick GuideScreening Tests Every Man Should Have
What can lower the PSA test result?
Medications commonly taken to treat benign enlargement of the prostate (BPH) such as finasteride (Proscar), dutasteride (Avodart), and a combination of dutasteride and tamsulosin (Jalyn) can decrease the PSA by about 50% within six to 12 months of starting their use. Another medication used to treat fungal infections, ketoconazole, can also lower PSA levels. Lastly, herbal supplements such as saw palmetto and those containing phytoestrogens, which are plant-derived chemicals with estrogen-like effects, can also lower the PSA level. It is important to tell your health care provider all the medications, both prescription and nonprescription, as well as any herbal preparations or health supplements that you are taking.
What is the accuracy of the PSA test?
One of the limitations of the PSA test is that PSA is not specific to prostate cancer and that it can be affected by several common conditions such as benign enlargement of the prostate, inflammation, and infection of the prostate. Furthermore, there is some variability in PSA results when using different testing equipment. One study showed that 25% (one in four) men who had an initial PSA result between 4 ng/mL and 10 ng/mL had a normal test result when it was repeated.
Only about 25% of men who have an elevated PSA between 4 ng/mL and 10 ng/mL will have prostate cancer identified on prostate biopsy. If one uses a lower cutoff of 3.1 ng/mL, PSA had a sensitivity of 32% and specificity of 87% for identifying prostate cancer. Sensitivity refers to the likelihood of a positive test result if the individual has the disease, whereas specificity refers to the likelihood the test is negative if the individual does not have the disease.
Another concern in addition to the low specificity in detecting the presence of prostate cancer is the inability of the test to discriminate between a more aggressive prostate cancer from one that is less likely to cause harm. This is thought to lead to overtreatment in up to 50% of men with prostate cancer.