Norms of general and free prostate-specific antigen( PSA)

Prostate-specific antigen( PSA) is a protein structure that is synthesized in prostate tissue. From the biological point of view, this substance belongs to kallikrein proteases. Entering into the seminal fluid, this substance contributes to its dilution and increase the mobility of male sex cells( spermatozoa).

PSA enters the bloodstream.

This property is extremely important for improving the ability to fertilize. The vast majority of the prostate-specific antigen is in the seminal fluid, and only a small part of it enters the bloodstream. To measure the concentration of this substance in the blood, ng / ml is used.

Regulatory indices

Fractions

In laboratory diagnosis, it is customary to isolate the fraction of free and common prostate-specific antigen.

General fraction. The total fraction is an antigen that is in a free state, and also associated with a substance called chymotrypsin. The value of the indicators of the total fraction lies in the fact that in the process of screening diagnostics it is possible to detect malignant neoplasms of the prostate gland. Modern diagnostic capabilities make it possible to identify additional diseases, which are characterized by an increase in the total fraction of this antigen.

Free fraction. The vast majority of the synthesized prostate-specific antigen binds to other protein structures of the blood. The amount that remains unbound is called a free faction.

Standards

Reliability of laboratory results depends on the method for determining the antigen fraction. Normal values ​​of free PSA do not exceed 10%.Their decrease speaks in favor of the development of the tumor process. On the other hand, if the increase in the total amount of prostate-specific antigen occurs due to the growth of the free fraction, the process is most likely benign.

If we talk about the normal indicators of each fraction, specialists in the field of urology recorded such figures, corresponding to the norm in men under 50:

• normal values ​​of the free fraction of PSA range from 0.04 to 0.5 ng / ml;
• the amount of total antigen fraction should not exceed 4 ng / ml;
• physiological parameters of the associated prostate-specific antigen range from 3.5 to 3.96 ng / ml.

With age, these figures change first to decrease, then to increase:

• in a man aged 50 to 59 years, the norm of the total fraction of the antigen is 3.5 ng / ml;
• from 60 to 69 years, this figure increases to 4.5 ng / ml;
• over the age of 70, the total PSA increases to 6.5 ng / ml.

Study of the level of prostate-specific antigen in the blood

To evaluate the parameters of this substance in the body, blood samples are analyzed. Since the content of this antigen in the bloodstream is minimal, very sensitive technologies are used to detect it. Measurement of the total fraction of the prostate-specific antigen is performed using a standard PSA test.

To assess the level of PSA, blood is taken for analysis.

What does high PSA mean?

An increase in the concentration of prostate-specific antigen in the bloodstream is triggered by its release when the integrity of the prostate tissue is compromised. This phenomenon can be caused by various pathological conditions, including malignant tumors of the prostate. During the examination, it is important to consider that this laboratory marker is not specific for prostate cancer.

A consistently high level of PSA indicates prostate cancer.

In addition, the increase in the marker occurs against the background of development of prostatitis .Other factors leading to the increase of this biologically active substance include:

• catheterization of the bladder;
• ejaculation;
• transrectal ultrasound;
• biopsy of prostate tissue.

Before carrying out this study, it is necessary to take into account the above-described factors that affect the level of the antigen. If we talk about prostate-specific antigen, as a marker of malignant pathology of the prostate gland, then this disease is characterized by a rapid and persistent increase in antigen content in the blood. The faster the amount of antigen increases, the more rapidly the tumor process develops.

If a man has an increase in this indicator, then to confirm the formation of the tumor process, he is recommended to undergo an additional examination, including laboratory and instrumental diagnostic methods. The most accurate method in this case is prostate biopsy.

This type of laboratory diagnosis is used not only to detect a progressive disease, but also to evaluate the conducted antitumor treatment, as well as to detect a relapse of the disease. An increase in antigen values ​​after the treatment indicates a recurrence of the malignant process.

If a man underwent a radical operation involving the complete removal of the prostate gland, then the results of the PSA tests should not include even a minimal amount of antigen. The harmful effect on the protein structure of the antigen is caused by ultrasonic waves, radiation therapy and chemotherapy. If the indicators of the marker remained positive, this indicates an incomplete removal of tissues with atypical( cancerous) cells. Also, this may indicate the spread of cancer beyond the prostate( see more "PSA level after prostatectomy")

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