- Prostate-Specific Antigen (PSA) testing can be a useful part of prostate cancer screening.
- Many men wonder what can skew a PSA test. Many factors like age and race can influence a man’s baseline PSA levels.
- Medications, infections, digital rectal exams, and other things can temporarily skew PSA results to be higher or lower than baseline.
- An MRI scan helps create a more complete picture of prostate health.
You may know prostate cancer is the most prevalent cancer (other than skin cancer) found in men. But you may not know that if the cancer is found early, before it spreads past the prostate, the five-year survival rate is nearly 100%. This means early prostate detection is key in successfully treating prostate cancer.
Knowing these factors can help you schedule your PSA test for higher accuracy and better discuss your results with a medical professional.
What Is a PSA Test?
A PSA test is a blood test that measures the protein levels of prostate cells. This helps determine how many prostate cells are in your blood. This can show your likelihood of having prostate cancers that are considered a high risk of spreading.
While no specific PSA score determines if a man has prostate cancer, most healthcare providers recommend further testing when someone has more than four nanograms of PSA per ml of blood (ng/mL).
Normal PSA Score Variations
Many normal variations can influence a PSA test score baseline.
Age is the biggest factor that can influence a PSA score, as the prostate gland enlargement that comes naturally with age, potentially resulting in PSA level changes.
Race also plays a role in a man’s normal PSA score. Black men who don’t have prostate cancer tend to have higher PSA scores than white men who don’t have prostate cancer.
Weight can influence a PSA score as well. Studies have shown men without prostate cancer with a higher body mass index (BMI) have a lower PSA level. This means someone who has a higher BMI probably has a lower baseline PSA level than someone with a normal range or low BMI.
What Can Skew a PSA Test?
In addition to natural variation in a man’s baseline PSA level, certain factors can temporarily skew a PSA test.
Here are six of the most common reasons for a rise or fall in PSA values:
Certain medications can cause a man’s PSA level to drop, including medications used to treat common concerns for aging men.
Drugs that can skew a PSA test include:
- NSAIDs: A class of pain medications that includes ibuprofen, Motrin, and Advil
- Statins: A class of cholesterol-reducing drugs like Lipitor
- Thiazide: A medication used to lower blood pressure
- Finasteride and Dutasteride: Medications used to treat an enlarged prostate, also called benign prostatic hyperplasia (BPH), and its symptoms
It’s important to let your healthcare provider know if you take or have started taking any of these medications before you get a PSA test.
Digital rectal exams (DRE) are exams used to manually feel the prostate. These exams are a routine part of most men’s yearly medical visits, and they were long thought to temporarily increase PSA levels. This increase is quite minimal, but it is still good to be aware of.
Ejaculation can increase a PSA score by up to 0.8 ng/dL for around 48 hours.
Infections like bacterial prostatitis and inflammation of the prostate can temporarily cause elevated PSA levels.
PSA values tend to return to baseline six to eight weeks after antibiotic treatment and when symptoms have resolved. Until then, you may want to delay your PSA screening.
5. Acute Urinary Retention
Acute urinary retention is an inability to fully empty the bladder through urination. This can be caused by swelling, infection, or trauma, and it can greatly skew a PSA test. After being treated for acute urinary retention, hold off on PSA testing for at least two weeks.
6. Prostate Biopsy
Prostate biopsies are a procedure in which a tissue sample is taken from the prostate. These are usually done when more information is needed to determine if someone has prostate cancer.
This can elevate a PSA level in as few as four hours after the procedure, and levels may remain elevated for up to four weeks. Avoid PSA testing for at least six weeks after a prostate biopsy.
Should I Test My PSA Levels?
Now that you know what can skew a PSA test and what can cause normal variations, let’s explore when you should test your PSA level.
The Centers for Disease Control and Prevention (CDC) recommends men talk to their healthcare provider about the risks and benefits of PSA testing prior to making a decision.
Men who are considered high-risk for prostate cancer should talk about PSA testing with their medical team when they turn 45 years old. High-risk groups include:
- Men with a first-degree relative who had prostate cancer before turning 65 years old
- African-American men
Otherwise, men should have this conversation when they are 50 years old.
Deciding when to start checking a man’s PSA level is complicated due to the potential for false-positive test results.
When a PSA value is concerning, it may require invasive testing like a prostate biopsy to better understand the prostate’s health. But in the case of a false positive, this can cause unnecessary pain, infection, and blood in the semen.
Recommended reading: Know Your Prostate Cancer Risk: Calculator and Risk Factors
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