PSA level: what is normal and when is PSA too high?

A normal PSA level is below 3 ng/ml. Below that limit the chance of prostate cancer is small and no further testing is needed. GPs in the Netherlands use that limit for men of every age, as set out in the NHG guideline on prostate cancer from the Dutch College of General Practitioners. A level of 3 or higher is a reason to see your GP. It is not yet a diagnosis: inflammation of the prostate, a bladder infection or a benign enlarged prostate can also give a result like that. Your report shows PSA in µg/l, and 1 µg/l is exactly the same as 1 ng/ml.

What is PSA?

PSA stands for prostate-specific antigen. PSA is a protein made by the prostate. The prostate is a gland below the bladder, around the start of the urethra, and it makes part of the seminal fluid. The protein keeps that fluid liquid, and a small amount of it always ends up in your blood. A PSA test measures how much of this protein is in your blood.

How much PSA is in your blood depends on what is happening in the prostate. The level rises as you get older, when the prostate grows larger in a benign way, with inflammation of the prostate and with prostate cancer. A high PSA therefore tells you that something is going on in your prostate. The number itself cannot tell you what that is, and further testing is needed to find out.

Normal PSA levels by age and the 3 ng/ml limit

Your GP reads a PSA result in three steps, and those steps apply at every age:

Online you will also find tables of PSA levels by age. The best known comes from an American study from 1993 of 471 healthy men. That table shows that PSA rises with age in healthy men, because the prostate grows larger over the years:

According to the NHG, limits by age have no proven added value, and international guidelines do not use them. A Dutch GP therefore uses 3 ng/ml, whether you are 50 or 70. A 65-year-old man with a PSA of 4 is below the limit in the table by age, while his GP refers him to a urologist if there is no infection. Laboratories also do not all use the same reference value, so check the limit printed on your own report as well.

What a raised PSA level does and does not tell you

No PSA level proves that you have prostate cancer, and no level rules it out either. A PSA test on its own cannot show prostate cancer. With a raised level, further testing by a urologist is needed to find out whether cancer is present. A low PSA level makes prostate cancer unlikely, but cannot rule it out completely.

That is why your GP also looks at symptoms, at prostate cancer in your family and at a physical examination. In that examination the GP feels the prostate through the anus, which is called a digital rectal examination. A prostate with an uneven shape or a firm lump is a reason for referral in itself, even with a normal PSA. The examination does not change your PSA, so it can take place before the blood draw.

A raised PSA level without cancer

A raised PSA level can also have a cause that has nothing to do with cancer. These causes can push your PSA up:

• A benign enlarged prostate. In many men the prostate grows with age, and a larger prostate makes more PSA.
• Inflammation of the prostate or bladder. After prostatitis or a bladder infection, your PSA can stay raised for up to 12 weeks.
• Ejaculation shortly before the test. In a study of 64 men, PSA rose after ejaculation in 87 percent of them. After 48 hours it was back to its earlier level in 97 percent.
• A long bike ride. In 129 men aged 50 to 71, PSA was on average 9.5 percent higher right after a ride of 55 to 160 kilometres.

Prostate cancer can raise your PSA as well. Your GP works out which cause applies to you, and a urologist does so afterwards if needed.

What the urologist does after a raised PSA level

If your PSA is 3 or higher and there is no infection, your GP refers you to a urologist. The urologist first estimates your risk, for example with the Prostaatwijzer. That is a risk calculator that combines your PSA with the outcome of the physical examination, among other things. If the risk is raised, further tests follow, starting with an MRI scan of the prostate. Only with an abnormal MRI does a biopsy follow: a small piece of tissue taken from the prostate with a needle. Thanks to the MRI, fewer men need a biopsy and fewer tumours are found that would never have caused symptoms.

You may hear about free PSA or about how fast your PSA rises. The ratio of free to total PSA can help to tell a benign enlarged prostate apart from cancer, but the measurement has many limitations. According to the NHG, the speed of the rise has no proven added value in making the diagnosis.

Lowering your PSA level

When an infection clears, your PSA falls again by itself. That is why your GP repeats the test 12 weeks after a prostate or bladder infection. You can avoid ejaculation or a long bike ride shortly before the test, so that a temporary rise does not distort your result.

Two medicines do lower your PSA strongly: finasteride and dutasteride. Doctors prescribe them for a benign enlarged prostate, and finasteride also for hair loss. After a year of use your PSA is on average about half as high, even when prostate cancer is present. If you use one of these medicines, tell the doctor who assesses your result, because they need to adjust your level for it.

Should you have your PSA tested?

That choice is yours to make once you know the pros and cons, and the NHG guideline says the same. A PSA test can find a prostate cancer that benefits from early treatment. Some forms of prostate cancer grow so slowly that they never cause symptoms. If the test finds such a tumour, you go through tests and sometimes a treatment you did not need. Across the whole population, early testing does not lower the chance of dying from prostate cancer.

A few things weigh in that choice:

• If your father had prostate cancer, your own risk is about twice as high. If your brother had it, it is about three times as high.
• Men of African or African-Caribbean descent have a higher risk of prostate cancer.
• If you carry the inherited BRCA2 variant, the NHG advises a PSA test and a physical examination every two years from the age of 45.
• With a life expectancy of less than 10 years, usually over the age of 75, a PSA test is not recommended.
• Urinary symptoms, such as passing urine more often or at night, rarely point to prostate cancer. The risk of prostate cancer is the same for men with and without urinary symptoms.

If you are unsure, talk it through with your GP, who can explain the pros and cons and look at your own situation.

Having your PSA measured without a GP

You can also have your PSA measured yourself, without a referral from your GP. You order the PSA test on its own or together with other blood values. Your blood is drawn at a partner location in a network of independent, certified laboratories. The result follows within about 48 hours, and a BIG-registered doctor assesses every result. How that works step by step is explained in ordering a blood test without a referral.

Plan the blood draw so that a temporary rise does not distort your result:

• Avoid ejaculation in the 48 hours before the draw.
• Do not go on a long bike ride in the 48 hours before it.
• Do you have a bladder or prostate infection now, or did you have one in the past 12 weeks? Then wait until those 12 weeks have passed before testing.
• If you use finasteride or dutasteride, tell the doctor who discusses your result with you.

If your PSA is 3 ng/ml or higher, take your result to your GP. Together you decide whether a repeat test or a referral is the next step.

Sources

• NHG-Standaard Prostaatkanker, Dutch College of General Practitioners (in Dutch).
• Oesterling JE et al. Serum prostate-specific antigen in a community-based population of healthy men. JAMA 1993;270:860-4 (PubMed).
• Tchetgen MB et al. Ejaculation increases the serum prostate-specific antigen concentration. Urology 1996;47:511-6 (PubMed).
• Mejak SL et al. Long distance bicycle riding causes prostate-specific antigen to increase in men aged 50 years and over. PLoS One 2013;8:e56030 (PubMed).