Prostate-Specific Antigen (PSA)
If you have symptoms of prostate disease, such as difficulty in passing urine, straining or taking a long time while urinating, hesitancy, weak flow, terminal dribbling or passing urine more frequently than usual especially during the night.
A blood sample is taken by needle from a vein in the arm. You are likely to be advised to avoid ejaculation and vigorous physical activity affecting the prostate, such as bicycle riding, during the two days before the blood test. A blood sample should not be taken until at least a week after a digital rectal examination.
Avoid ejaculation for 48 hours before sample collection as this has been associated with elevated prostate specific antigen (PSA) levels; the sample should also be collected prior to your healthcare professional performing a digital rectal exam (DRE) and prior to, or 6 weeks after, a prostate biopsy. PSA may remain high for many months following a urinary tract infection, and for 48 hours following vigorous exercise, especially riding a bicycle).
Blood is being tested for the amount of PSA it contains. PSA is a protein produced mainly by cells in the prostate gland and can be a useful indicator of prostate cancer. This protein can be found in all people with a prostate; however raised levels may indicate an infection of the prostate gland (prostatitis), benign prostate enlargement or prostate cancer. In blood, PSA is present both as free PSA and as complexed PSA bound to other blood proteins. The free PSA test measures the percentage of the total PSA that is not bound to proteins in the patient’s blood.
How is it used?
When is it requested?
Current evidence does not indicate that screening asymptomatic men for prostate cancer would reduce mortality, the Department of Health's Prostate Cancer Programme has developed the Prostate Cancer Risk Management Programme. This is explained under Without symptoms of prostate disease aged 50 and over.
Currently there is no evidence to show that the overall benefits of a PSA- based screening programme outweighs the risks. PSA is still a poor test for prostate cancer detection (low specificity) and it has led to harm of over-diagnosis and over-treatment in up to 50 % of men. A PSA test does not distinguish a slow-growing cancer from a fast-growing cancer.
Risk factors for prostate cancer include:
•Family history of prostate cancer
•Being overweight or obese (especially in advanced prostate cancer)
Your healthcare professional will take these risk factors into account to give you the best available information and support your decision.
The Public Health England website has a guidance document on Prostate Cancer Risk Management Programme (PCRMP). It includes a summary sheet on advice for well men aged 50 and over.
What does the test result mean?
A normal PSA level ranges from 0–4 nanograms/mL. However, the upper level of normal may vary according to age and race.
The 'normal' value for total PSA varies with age and is generally considered to be less than 3.0 nanograms (ng) per mililitre (mL) in men aged 50-69 years. There are age specific PSA thresholds recommended by recent 2021 NICE guideline, for people with possible symptoms of prostate cancer Taking into account patient preferences and comorbidities should also lead to a more patient-centred approach to referral.
Most men will have a PSA level less than 3 nanograms/mL. About 3 in 4 men with a raised PSA level (3 nanograms/mL or higher) will not have cancer. Around 15% of men with a normal PSA do have cancer.
A high serum PSA result >3 ng/mL alone does not automatically lead to other investigations e.g; prostate biopsy. There are several other factors to be considered; such as prostate size, digital rectal examination (DRE) findings, age, ethnicity, family history of prostate cancer, body weight, co-morbidities, history of any previous negative biopsy or any previous PSA history. Your healthcare professional may consider these factors along with raised PSA (> 3 ng/mL) result when referring patients to specialist care.
Total PSA level greater than 10.0 ng/mL may indicate a high probability of prostate cancer. Results between 2.0 ng/mL and 10.0 ng/mL may be due to BPH, a non-cancerous swelling of the prostate that occurs most frequently in older men. Increased total PSA levels may also indicate a condition called prostatitis, which is caused by an infection.
There is some evidence that the free PSA ratio (the percentage of total PSA not bound to proteins) can help predict the probability of cancer, especially in patients with total PSA levels in the 'grey-area’ range of 2.0 to 10.0 ng/mL. A free-PSA test result above 25% is thought to suggest a lower risk of cancer, whereas a lower percentage suggests a higher probability of disease. This ratio may help reduce the number of unnecessary biopsies. In most cases, test results are reported as numbers rather than as "high" or "low", "positive" or "negative", or "normal". In order for the doctor to understand laboratory results it is necessary for them to know what the reference range (or ‘normal value’ range) is for the laboratory where the test is performed. Reference ranges can be influenced by the test method and instrument used by laboratory. To learn more about reference ranges, please read the article, Reference Ranges and What They Mean.
Is there anything else I should know?
Prostate biopsy or operations on the prostate will significantly elevate PSA levels. A blood test for PSA measurement must be performed before surgery or six weeks after.
Ejaculation and vigorous physical activity affecting the prostate, such as bicycle riding, may cause a temporary rise in PSA. A blood sample should be taken either before a digital rectal examination, as pressure on the gland during the examination will lead to an increase in the PSA value, or alternatively after at least a week after the examination. Some chemotherapeutic drugs, such as cyclophosphamide, methotrexate, and also other medications such as aspirin, statins, diuretics, finasteride, and dutasteride may affect PSA results. Before a PSA test, people should not have an active urinary infection or had one within the previous 6 weeks.
If I have prostate cancer, what are my options?
Are the recommendations for PSA testing different for different ethnic groups, such as those of Afro-Caribbean descent?
Will PSA testing detect all prostate cancers?
I have heard my doctor use the terms PSA Density, PSA Velocity, PSA Doubling Time. Please explain what these are.
PSA Density refers to the relationship of the PSA level to the size of the prostate measured by ultrasound examination. People with larger prostates tend to produce more PSA, and so those with a benign enlarged prostate (BPH) can have higher 'normal' PSA levels.
PSA Velocity refers to how quickly PSA results change over time. There is evidence to indicate that the development of prostate cancer requiring treatment is associated with a faster increase in the PSA value over time.
These are taken into consideration when offering prostate biopsy if there is a strong suspicion of prostate cancer.
PSA Doubling Time is the time it takes for the PSA value to double. This may be useful in following treatment and determining the type of treatment.
Elsewhere On The Web
Prostate Cancer UK: Prostate Cancer Tests
NICE guidelines NG131
NHS Cancer Screening Programmes: Prostate Cancer Risk Management
Macmillan cancer support
Public Health England; Prostate cancer risk management programme (PCRMP): benefits and risks of PSA testing