What is PSA and should I test it?

If you’re considering a PSA test, it’s important to understand what this test can and can’t tell you. Here’s what you need to know.

A PSA blood test is used to screen for prostate cancer.  

Like most tests, a PSA test isn’t perfect. Often the results aren’t as cut and dried as we’d like them to be. For example, around three-quarters of men with a raised PSA don’t have prostate cancer [1]. This is known as a false-positive result, and it can lead to unnecessary worry. 

The flip side is also true: sometimes a PSA result is normal in men with prostate cancer. This is rarer but may be harmful if a fast-growing cancer is missed.  

So, is it worth getting a PSA test and what do your results mean? 

In this article we cover:  

What is PSA?

PSA, or prostate-specific antigen, is a protein made by healthy cells in the prostate. As you get older, the prostate gets bigger, so it’s normal to see PSA levels gradually increase over time.  

Prostate cancer can cause PSA levels to shoot up, so in some situations, it can be useful as a screening tool. It can help to detect prostate cancer at an earlier stage when treatment may be more effective. But PSA can be raised for other reasons and give a false result.  

We have no dedicated PSA screening programme in the UK. More evidence is needed to prove that the benefits of testing everyone outweigh the risks of unnecessary investigations and treatments and any anxiety it may cause. Instead, PSA testing mostly comes down to personal choice.  

Should I take a PSA test?

In the UK, we have an informed choice programme. This means if you’re 50 or over and have weighed up the pros and cons of testing, you can ask your GP for a PSA test. If you’re under 50, it’s still possible to get prostate cancer, but your risk is much lower [2].  

In some cases, your GP may give a valid reason for not testing. For example, if your general health means you wouldn’t be suitable for treatment of prostate cancer, there is little benefit in having the test.  

If you’d rather take a test at home, you can do so with our finger-prick PSA (Prostate Specific Antigen) Blood Test.  

But before making any decision, you should consider the upsides and downsides of testing.    

Advantages of a PSA test: 

  • It can help to pick up prostate cancer before you have symptoms 
  • It may detect a fast-growing cancer at an early stage when treatment is likely to be more effective 
  • A regular PSA test may be useful for some people who are at increased risk of prostate cancer 

Disadvantages of a PSA test:  

  • A PSA result can be raised even if you don’t have cancer and lead to unnecessary anxiety and investigations like a scan or biopsy — in three out of four men who have a raised result, no prostate cancer is found [1]
  • The test might miss prostate cancer — one in seven men with a normal PSA may have prostate cancer [3]
  • It might detect a slow-growing cancer that would otherwise have been harmless — it may make you worry or even lead to treatment you don’t need 

The investigations and treatments for prostate cancer come with their own side effects. For example, a biopsy can cause pain, infection, or bleeding. Surgery can lead to complications like urinary symptoms or erection problems which might be lifelong. Therefore, it’s important to consider whether you’d explore these options if your PSA level were to be raised.  

There’s no right or wrong answer about whether you should have a test — it’s a personal decision. Another factor to consider is whether you may be at higher risk. Visit our prostate cancer blog for more information on whether you may be at increased risk. 

If you’re trans or non-binary, your risk may be slightly different. 

Trans women, non-binary people, and PSA

Both trans women and non-binary people who were assigned male at birth have a prostate, even after genital reconstructive surgery, so it’s still possible to get prostate cancer. The same is true for some intersex people. Your risk will vary according to whether you’ve had treatment that affects your testosterone levels.  

If you’re not taking gender-affirming hormones and you’ve not had gender-affirming surgery, your risk is the same as cis men (people whose gender identity and sex assigned at birth are both male) [4].  

Testosterone-lowering therapy and gender-affirming surgery 

People who take medications that lower testosterone (feminising hormones or testosterone blockers) or have had gender-affirming surgery have a slightly reduced risk of prostate cancer compared to cis men of the same age. But both these treatments can falsely lower PSA levels. This blood test should therefore be interpreted with caution, taking hormone regimen and testosterone levels into consideration, as it may be falsely reassuring [4]. 

Because there isn’t much data available on PSA levels in trans women, it makes it difficult to define a normal PSA value for this population.  

If you have questions about your risk as a trans woman or non-binary person, Prostate Cancer UK is a great place to learn more.  

What is a normal PSA level?

There is no one PSA reading that is considered normal. 

Whether or not your doctor refers you to a specialist will be down to many factors, including their own experience and judgment, local guidelines, any symptoms you may have, and examination findings.  

PSA level thresholds differ with age. You may be referred to a specialist if your PSA level is: 

Age  PSA level
40–49 > 2.5ng/ml
50–59 > 3.5ng/ml 
60–69 > 4.5ng/ml
70–79 > 6.5ng/ml

*These reference ranges are provided by NICE and apply to patients with possible symptoms of prostate cancer [5]. There are currently no widely accepted reference ranges specifically for asymptomatic screening (patients with no symptoms).  

What causes a high PSA?

If you have a raised PSA result, this doesn’t mean you have prostate cancer. In fact, there are many reasons this may happen, most of which are benign or treatable.  

Potential causes of raised PSA: 

  • Enlarged prostate — the prostate naturally gets bigger with age, and this is reflected in gradually increasing PSA levels. Some men develop benign prostatic hyperplasia (BPH). This condition is most common in men over 50 and it can cause symptoms, like affecting how you pee. 
  • Inflamed prostate — an inflamed prostate is known as prostatitis. It’s often due to a bacterial infection which may cause symptoms such as pain and difficulty peeing. 
  • Urinary tract infection (UTI) — UTIs can cause PSA levels to increase. It’s best to wait eight weeks after the infection has been treated before retesting PSA [6].  
  • Recent ejaculation — PSA levels rise in some men following ejaculation and may remain high for 24–48 hours afterwards. Therefore, avoid ejaculating before taking your test.  
  • Direct prostate stimulation — recent prostate stimulation, including a rectal examination or receptive anal sex, might raise your PSA levels for a while. It may be best to wait a week before testing.  
  • Prostate biopsy or injury — procedures and biopsies of the prostate cause a spike in PSA levels which should return to normal within six weeks [3]. 
  • Urinary catheter — If you use a urinary catheter, you may need to wait up to six weeks after its removal before testing PSA levels. 
  • Constipation — there’s some evidence that forced bowel movements might affect PSA, so it’s best to treat constipation before testing [7]. 
  • Cycling and horse-riding — saddle sports can put pressure on the prostate. To reduce any potential effect, you can abstain from the sport for 24–48 hours [8,9]. 
  • Vigorous exercise — you might be advised to avoid vigorous exercise for 48 hours before a test. 

What can reduce PSA? 

Some medications reduce PSA levels. These mainly include drugs that aim to reduce the size of the prostate.  

Medications that may reduce PSA include:  

  • Finasteride (Proscar/Propecia) 
  • Dutasteride (Avodart) 

It’s important to let your healthcare provider know if you’re taking these medications when taking a PSA test, as it can falsely lower your result.  

Recently, other medications like statins and non-steroidal anti-inflammatory drugs (NSAIDs) have been thought to lower PSA. While this may be true it’s unlikely this effect is significant enough to compromise the benefits of PSA testing [10].  

Do I need further investigations?

PSA screening is just the first step. If your result is only slightly raised, your doctor may suggest repeating the test in a few weeks.  

If your result is repeatedly raised or you have other signs and symptoms of prostate cancer, you may be referred on to a specialist for further tests, such as an MRI. This can help determine whether you may need a biopsy. Remember that not all prostate cancer is aggressive, and in some cases might not require treatment.  

Further support 

As well as your GP, Prostate Cancer UK can help support you with questions you may have about prostate cancer. There, you can chat with a specialist via their online chat or over the phone. They also list local support groups and give practical advice on a variety of topics. 


References 

  1. Prostate-Specific Antigen (PSA) Test - NCI [Internet]. 2022 [cited 2022 Nov 10]. Available from: https://www.cancer.gov/types/prostate/psa-fact-sheet
  2. Prostate cancer incidence statistics [Internet]. Cancer Research UK. 2015 [cited 2023 Jan 5]. Available from: https://www.cancerresearchuk.org/health-professional/cancer-statistics/statistics-by-cancer-type/prostate-cancer/incidence
  3. PSA test [Internet]. Prostate Cancer UK. [cited 2022 Nov 10]. Available from: https://prostatecanceruk.org/prostate-information/prostate-tests/psa-test/
  4. Prostate cancer in transgender women: what does a urologist need to know? [cited 2022 Nov 14]; Available from: https://bjui-journals.onlinelibrary.wiley.com/doi/10.1111/bju.15521
  5. Assessment | Diagnosis | Prostate cancer | CKS | NICE [Internet]. [cited 2023 Jan 12]. Available from: https://cks.nice.org.uk/topics/prostate-cancer/diagnosis/assessment/
  6. Mokete M, Palmer AR, O’Flynn KJ. High result in prostate specific antigen test. BMJ. 2003 Aug 14;327(7411):379.
  7. Bayraktar Z, Inan EH, Bayraktar V. Effect of constipation on serum total prostate-specific antigen levels in men. Int J Urol. 2012 Jan;19(1):54–9.
  8. Jiandani D, Randhawa A, Brown RE, Hamilton R, Matthew AG, Kuk JL, et al. The effect of bicycling on PSA levels: a systematic review and meta-analysis. Prostate Cancer Prostatic Dis. 2015 Sep;18(3):208–12.
  9. Mejak SL, Bayliss J, Hanks SD. Long Distance Bicycle Riding Causes Prostate-Specific Antigen to Increase in Men Aged 50 Years and Over. PLoS One. 2013 Feb 13;8(2):e56030.
  10. Vettenranta A, Murtola TJ, Raitanen J, Raittinen P, Talala K, Taari K, et al. Outcomes of Screening for Prostate Cancer Among Men Who Use Statins. JAMA Oncology. 2022 Jan 1;8(1):61–8.

 

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