A prostate specific antigen, PSA for short, is a protein that is produced by the prostate. It is mainly contained in semen, however, a small amount of antigen can be detected in the blood of quite healthy men. By changing its level, one can judge the presence of oncology of the prostate. Consider a blood test for PSA with decoding.
Why do you test blood for PSA?
There are at least two reasons why blood tests for PSA in men are performed. First of all, it is necessary for the early detection of a cancer in the prostate gland:
- the test is conducted if there is a suspicion of oncology;
- The test results are used to detect the asymptomatic course of prostate cancer.
Also, a PSA blood test is performed to monitor the effectiveness of cancer therapy or when recurrences and progression of the disease occur. PSA acts as a tumor marker, that is, a substance that is in the body if there is cancer. When this indicator decreases or returns to normal, it means that the cancer responded well to treatment.
The lowest level serves as a reference value for the following analysis:
- PSA should fall to almost imperceptible level or less than 0.1 ng / ml in men who received treatment with surgery.
- In men who have undergone radiation therapy, it also decreases after treatment. Despite the fact that the prostate was removed, the benign parts of the gland continue to produce a small amount of antigen - up to 2.0 ng / ml.
An increase in PSA levels may mean that the cancer does not respond to treatment and the tumor develops. This may be an early sign of relapse. However, in the case of a single PSA increase, it is not necessary to imply that the disease has recurred, especially if preceded by radiation therapy. A temporary increase in the antigen, the so-called rebound, occurs in about half of the patients, usually within 4 years after treatment. In such cases, the indicator goes down again without any additional impact.
This should take into account the fact that high PSA does not necessarily indicate cancer. Only every fourth patient will actually develop a cancerous tumor of the prostate gland. The rest have benign conditions, for example, inflammation of the prostate gland or an increase in its size.
Norm PSA: interpretation of analysis results
As already mentioned, a small concentration of PSA in plasma in the absence of disease is normal. The change in its level can occur for various reasons. It depends on age. PSA is prone to a tendency to gradually increase by the age of sixty men, since the size of the prostate gland by this time become larger.
The table shows the PSA rate in the analysis, taking into account the patient's age. And although many doctors consider the norm to be less than 4 ng / ml, the standard value is mainly determined by the age of the man. If for a forty-year-old PSA is up to 4 ng / ml, then for a seventy-year-old man - more than 4 ng / ml. Consequently, an increase in PSA levels in the blood significantly increases the risk of a cancer. There is no maximum limit.
In medical practice, there are cases of normal PSA values in a person suffering from prostate carcinoma. In general, many diseases of the prostate correspond to a high PSA level. It can also rise in such cases as:-
- benign enlargement of the prostate with hyperplasia;
- inflammation or infection of the prostate;
- recent rectal exam, biopsy or transrectal ultrasound;
- sexual activity, recent ejaculations.
There are two main forms of PSA in plasma - free and bound. The first form is unconnected and circulates freely in the blood. Free PSA levels are higher in benign prostate conditions.
The linked form is the combination of antigen molecules with other proteins. In carcinoma of the prostate, iron produces more PSA of the associated type. With a decrease in free PSA and an increase in the bound form, the presence of a cancer is more likely.
What is a generic PSA that is listed in the table? This is the sum of the amount of free molecular form of the prostate specific antigen and its associated. The rates of free and total PSA are interrelated by the following relationships:
- In the presence of prostate cancer, the ratio of free PSA values to the total amount of antigen is low.
- The value of the total PSA level, taking into account the age category, equal to 4-10 ng / ml, is the reason for conducting a blood test for its free form. Also with this value, additional studies are being conducted - transrectal ultrasound and prostate biopsy.
What you need to know when preparing for the analysis?
In principle, no special preparation for PSA analysis is required. However, it should be borne in mind that the value of the indicator in some cases may temporarily exceed the norm. That is why the following points should be taken into account:
- refrain from ejaculation for at least 2 days prior to sampling;
- not later than three days before the tests, all procedures for intensive massage of the prostate gland should be completed;
- in the case of TRUS, blood sampling should be done only 7 days after ultrasound;
- biopsy of the prostate suggests that PSA testing will be done no earlier than 42 days later;
- It is necessary to inform the doctor about taking medications that provide treatment for benign prostate gland changes, because these drugs can reduce PSA.
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The distinctive advantage of a PSA blood test is the early detection of a cancer in the prostate. This means the timely start of therapeutic effects on the tumor, that is, before it begins to grow and metastasize to neighboring tissues and organs. So, cancer treatment will be more effective.