Prostate-specific antigen (PSA) levels and testing

This page was reviewed under our medical and editorial policy by

Sean Cavanaugh, MD, Chair, CTCA Department of Radiation Oncology.

This page was updated on June 9, 2022.

Prostate-specific antigen (PSA) is a protein produced by both normal cells and cancer cells of the prostate gland. This means even without cancer, a man will have a level of PSA. The prostate-specific antigen (PSA) test is a blood test that measures a protein that is produced by normal healthy prostate cells and cancerous prostate cells.   

The level of PSA in the blood is often high among men with prostate cancer, but there’s no clear-cut “normal” or “abnormal” PSA test result level. It can vary from person to person. PSA screening isn’t appropriate for every person. The American Cancer Society recommends consulting first with a doctor. The decision to have a PSA test should be made after considering the uncertainties surrounding PSA testing, as well as the potential risks and benefits. 

However, if a man does have prostate cancer, PSA testing may be a valuable monitoring tool. 

PSA levels and how they can vary

Experts’ views regarding PSA levels have changed over the years.  

Previously, PSA levels of 4.0 ng/mL (nanograms per milliliter) and lower were considered normal. For men with test results showing levels above 4.0 ng/mL, doctors would recommend a prostate biopsy. But in more recent years, studies have demonstrated that some men with PSA levels lower than 4.0 ng/mL can have prostate cancer, and many men with PSA levels higher than 4.0 ng/mL don’t have prostate cancer.  

Moreover, a number of factors can cause PSA levels to fluctuate. Prostatitis, urinary tract infections, prostate biopsies, and prostate surgery may also cause PSA levels to rise. On the other hand, certain drugs can cause PSA levels to lower, such as finasteride (Propecia®) and dutasteride (Avodart®).   

Generally, the higher the PSA level, the more indicative it is of prostate cancer, and an ongoing rise in PSA levels may also signal prostate cancer.  

  • Men whose PSA level is between 4.0 ng/mL and 10 ng/mL have a 1 in 4 chance of having prostate cancer. 
  • When a PSA level is over 10 ng/mL, there is a more than 50 percent chance of having prostate cancer.

Risk factors that may raise or lower PSA levels

There are many other risk factors that can raise PSA levels, including:  

  • Enlarged prostate, also called benign prostatic hyperplasia (BPH), which is common in older men 
  • Older age, which naturally results in higher PSA levels 
  • Ejaculation within 1 to 2 days of the blood draw 
  • Riding a bicycle, which may raise levels for a short time after 
  • Certain urologic procedures, like cystoscopy
  • Certain medicines, such as male hormones  

Factors that may specifically lower PSA levels—even among men with prostate cancer—include: 

  • 5-alpha reductase inhibitors, which treat BPH or other urinary symptoms 
  • Some medications, such as aspirin or statins  
  • Herbal mixtures or supplements, which could skew the results 

In certain cases, a factor that lowers PSA does lower the risk of developing prostate cancer. In others, however, lowering the PSA level has no effect and could be harmful, as prostate cancer could go undetected if the level drops too far.  

For all of these reasons, it’s important to speak with your doctor about factors that might apply to you when considering testing and interpreting test results.

PSA screening guidelines

There are no firm screening recommendations for all men, because levels can fluctuate and results need to be interpreted with caution. Most medical organizations recommend that men consult with their doctors before deciding to undergo PSA screening. 

The American Cancer Society recommends that men discuss screening with their doctor at three points in their life. These include: 

  • At age 40 for men who are at highest risk for prostate cancer (more than one first-degree relative who had prostate cancer at a young age) 
  • At age 45 for men who are at high risk for prostate cancer (first-degree relative diagnosed before 65 or African-American heritage) 
  • At age 50 for men who are at average risk

How a PSA test is used for prostate cancer

Typically, the PSA test is performed in conjunction with a digital rectal exam (DRE) for a more accurate picture of signs of cancer. During the DRE, your doctor will insert a gloved, lubricated finger into the rectum to feel for any bumps or hard areas on the prostate.  

  • If you choose to undergo prostate cancer screening and high PSA levels are found:  
  • Your doctor may recommend a second PSA test to confirm results.  
  • If the second result comes back high, it might recommend that you continue to have PSA tests and DREs to monitor any potential changes over time.
  • There are several types of PSA tests that your doctor may order. Sometimes a percent-free PSA test is performed to help guide your doctor on whether or not a prostate biopsy is needed. This is because men with lower amounts of free PSA floating in the blood are more likely to have prostate cancer. Your doctor may also order other PSA test options such as complexed PSA, a Prostate Health Index (PHI) or 4Kscore test.
  • If PSA levels continue to go up—or if a suspicious lump is found during a DRE—more tests may be recommended to determine the cause.
  • If prostate cancer is suspected, a prostate biopsy may be recommended. 

If your PSA results are considered normal or low, and prostate cancer is unlikely, future screening is often based on the level at the time of testing. According to the American Cancer Society:  

  • If your level is below 2.5 ng/mL, testing every 2 years may be recommended. 
  • If your level is higher than 2.5 ng/mL, yearly testing may be recommended. 

How a PSA test is used for cancer care

If you have prostate cancer, PSA testing, along with other results, may help your doctor determine:  

  • The stage of cancer 
  • If other scans or tests or treatments are needed 
  • How well the treatments are working, among other post-treatment monitoring needs  

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