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Prostate Specific Antigen (PSA)

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Why is Prostate Specific Antigen done?

• This test is done to screen for prostate cancer and to assess the need of a biopsy.

• To check the effectiveness of the treatment for prostate cancer.

• To detect the recurrence of prostate cancer.

When Prostate Specific Antigen is done?

• When a person has signs and symptoms of prostate cancer such as, difficulty in urination, painful or frequent urination.

• It may also be done during the treatment and follow up of prostate cancer.+

• As a screening test for prostate cancer, in men at higher risk, such as older men, family history and others. It is advisable to consult your doctor if you want to get it tested with no symptoms.

What sample is needed and how is Prostate Specific Antigen collected?

The blood sample is taken from the veins present in the arm, preferably from the site of elbow fold.


Read MoreProstate Enlargement Diagnosis (Benign prostatic hyperplasia/BPH)


What are the preparations needed before the test?

• Avoid ejaculation: for about 1 to 2 days before giving sample. This has been associated with temporary high levels of PSA.

• Avoid riding a bicycle: this may occur due to co person of the prostate.

• Avoid certain medicines: such as 5 alpha reductase inhibitors, herbal supplements or testosterone. Five alpha reductase inhibitors (dutasteride or finasteride) are the medicines which are usually taken for BPH. If you are taking above mentioned medicines or any other medicines you should inform your doctor before giving sample for the test.

• Avoid prostate specific procedures: the blood sample should be collected before the digital rectal exam (DRE) and prostate biopsy, because both can elevate Prostate Specific Antigen (PSA) levels.

What is tested?

Prostatic specific antigen (PSA)

is a protein that is predominantly produced by the cells of prostate. The prostate is a small gland found in men, just below the bladder surrounding the urethra. The function of the prostate is to produce a fluid that constitutes semen which is required to carry sperms and provide nutrition to them. Majority of the PSA produced by the prostate is released into the semen. Only, a small amount of PSA gets released into the blood. In the blood, PSA is found in two main forms- complexed (cPSA, attached to other proteins) and free (fPSA, unattached). The commonly performed test measures the total PSA levels which is the sum of cPSA and fPSA in the blood. Sometimes, free PSA test is also done to determine the need of biopsy when total PSA is mildly elevated.

Role of Prostate Specific Antigen (PSA) test

The PSA test measures the level of PSA in blood which gets elevated significantly when prostate cancer develops. This forms the basis of doing a PSA test for screening prostate cancer. However, raised levels (usually to a lesser extent) of PSA can also be seen in other conditions of prostate such as prostatitis (swelling) and benign prostatic hyperplasia (enlargement). Thus, Prostate Specific Antigen test is not used to confirm the diagnosis of prostate cancer but to raise suspicion of prostate cancer. The diagnosis of the prostate cancer is established by means of prostate biopsy which allows examination of the prostate tissue under a microscope. PSA test when used along with digital rectal examination helps to identify people who needs further evaluation with biopsy.

Further course of action

If the biopsy shows presence of tumor cells in prostate, then the next thing is done to decide the extent of the spread of the tumor and the treatment required. Another important thing that is considered is the aggressiveness of the tumor which suggest its tendency to spread. Most cases of prostate cancer grow very slowly over a period of time. The side effects of the treatment and the age of the patient decides what approach would be suitable for the person.

know more…

What are the recommendations for PSA screening?

U.S. Preventive Services Task Force (USPSTF) recommendation

has devised some recommendations to suggest who should opt for screening.

• Men aged between 55 to 69 years of age: are advised to take decision whether to undergo screening only after discussing with their doctor about the possible benefits and harms of the screening. They should also discuss about the possible benefits and risks associated with other tests and treatment.

• Men aged 70 years or above: are recommended not to undergo Prostate Specific Antigen screening for prostate cancer.

MSKCC recommendation

recommends different set of guidelines which considered men from age 45 years to 76 years and above. The guidelines are as follows:

• Men aged 45 to 49 years: should have a PSA test to know the baseline level of PSA.

• Men aged 50 to 70 years: should get their PSA levels checked to screen for prostate cancer.

• Men aged 71 to 75 years: should discuss with their doctor to get the PSA test done or not. The doctor would consider the past PSA levels and general health condition.

• Men aged 76 years or above: are not recommended to undergo PSA test.

What does the test result mean?

The interpretation of PSA test is based on the value of the PSA and the associated risk factors. There is no definite threshold PSA value to diagnose the prostate cancer, however the chances of prostate cancer increases with increase in the PSA levels. Many different laboratories may have different parameters and thus different reference values. The commonly used reference values and their interpretation are given below:


PSA levelsInterpretation
Less than 4 ng/ml• Prostate cancer- unlikely
More than 10 ng/ml• Increased risk of prostate cancer (more than 50% risk)
4 ng/ml to 10 ng/ml
(gray zone or borderline zone)
• About 25% increased risk of prostate cancer
• Other conditions of prostate such as BPH or prostatitis

Free PSA to PSA (total PSA) ratio

Prostate tumors predominantly produces complexed Prostate Specific Antigen (cPSA). Whereas, the benign prostate cells predominately produces free PSA. So, if the men in the gray zone (4 to 10ng/ml)have low level of free Prostate Specific Antigen (PSA), then it means they have high level of cPSA and high risk of developing prostate cancer. On the contrary, if they have high level of free PSA and low level of cPSA, then the risk is low. The correlation between free and total Prostate Specific Antigen level can help the doctor to identify, whether a prostate biopsy is necessary or not.


Additional methods that may help to make PSA results more reliable:

• Age specific PSA ranges: PSA level are found to be normally higher in older men than in younger ones, even in absence of cancer. The PSA levels within the gray zone might be cause of be a cause of concern in a 50 year old men but not in a 75 year old. Due to this reason it is advisable to compare the results with men of similar age group.

• PSA velocity: this suggests the elevation of the PSA levels in a men over a period of time. In normal circumstances the PSA levels increases slowly over a period of time. When this occurs rapidly in a shorter span of time it may suggest possibility of prostate cancer.

• PSA doubling time: is another form of Prostate Specific Antigen velocity test; it checks how quickly the Prostate Specific Antigen levelsget doubled over a period of time.

• PSA density: generally, the PSA levels are higher in men with higher volume of prostate even in absence of cancer. PSA density calculates the volume adjusted levels of the PSA. This is done by measuring the volume of the prostate by trans-rectal ultrasound and dividing it with the PSA levels obtained.

Once the treatment starts, then the level of PSA should start falling. When the treatment gets completed, then the level of PSA should be very low. If the level is not falling as expected, then it may suggest the treatment has not been very effective. In the follow up period after treatment, the Prostate Specific Antigen test is done in regular intervals to monitor the development of recurrence. Since minuscule increase can be significant, therefore PSA test should be done at the same laboratory so that there are no variations in the results.

know more…


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