Blood test for PSA and its interpretation

What is a blood test for PSA

? One of the most important exocrine male genital organs is the prostate gland, which secretes the secretion of the prostate( part of the sperm) and functions as a valve that blocks the exit from the bladder. Among cancer diseases affecting men, the leading position is prostate cancer, diagnosed, mainly, in people older than 55 years. A feature of this oncopathology is a slow asymptomatic development.

Prognosis of prostate cancer treatment depends on the timely detection of the disease - the earlier a malignant tumor is detected, the greater the chance that the therapy will yield positive results. With the purpose of early detection of oncological pathologies, a highly informative diagnostic method is used - a blood test for PSA( prostatic specific antigen).

The essence of the diagnosis is to determine the level of a specific oncomarker( the products of vital activity of tumors or substances produced by healthy tissues in response to the penetration of cancer cells into the body) in the blood serum. Prostate-specific antigen( or PSA) refers to substances whose molecules consist of several amino acid residues( polypeptides) and are biochemical classification proteases( an enzyme that cleaves peptide bonds between amino acids in proteins).

PSA is produced by the cells of the excretory canals of the prostate gland, while it is capable of producing both normal and tumor structural-functional units. Under normal conditions, the antigen enters the ejaculate and opalescent fluid secreted by the prostate. Very few antigens enter the bloodstream. In the formation of organ-specific tumors in the prostate gland( cancer or adenoma), the PSA level in the serum increases significantly, which is the reason for the biopsy to confirm the presence of oncopathologies.

The blood test for PSA has begun to be used to detect early forms of prostate cancer since the late 1980s. The statistical data collected during the time of application of PSA-screening testify to the high efficiency of this diagnostic method( the reduction in cancer mortality due to timely treatment was 25%).The prostate-specific antigen has several molecular forms:

1. Free.
2. Associated with alpha-1-antichymotrypsin( an inhibitor of proteinases, the increase in concentration is associated with the development of tumor processes).
3. Associated with alpha-2-macroglobulin( endopeptidase inhibitor, not detectable during immunochemical laboratory tests, level increase is caused by acute or chronic diseases).

Diagnostic values ​​are the free PSA and alpha-1-anti-chymotrypsin levels, the sum of which is total PSA.When screening for prostate cancer, the level of the total antigen is initially determined, and if its increased content is detected, a transcript is made in the section of molecular forms.

When the

is appointed In the world practice there is no generally accepted position regarding the advisability of prescribing PSA screening without clear grounds. Supporters of the regular survey justify their opinion with the possibility of timely detection of the pathology of the gland, and opponents - insecurity of interference into the structure of the prostate and the danger of overdiagnosis( erroneous conclusion about the presence of the disease).

Based on theoretical data and statistical information, annual determination of the level of the prostate-antigen is advisable to be performed by men starting at the age of 45 years. For persons of younger age, indications for the appointment of a blood test for PSA are the appearance of signs of prostatitis or symptoms characteristic of other diseases of the prostate:

• nocturia( frequent urination at night);
• hereditary predisposition to oncological diseases;
• difficulty urinating, a lasting feeling of a full bladder;
• chronic pelvic pain;
• batch discharge of urine and other disorders of the urinary system.

In addition to diagnosis for the prevention of development of tumor formations, the analysis is assigned to monitor the health status of patients who have previously been diagnosed with prostate pathologies. Determination of the amount of prostate-specific antigen is indicated in the following cases:

• after radical therapy of a malignant tumor( the analysis is carried out 1 time in 3 months);
• during treatment of prostate cancer( to monitor ongoing treatment);
• if there are signs of structural changes in the organ during rectal examination;
• if vascular disorders in the gland( ischemia, myocardial infarction) were previously identified.

Due to the specificity of the different molecular forms of the prostate-specific antigen, the indications for delivery of general and free PSA are different:

Indications for the determination of the total PSA	Indications for the determination of free PSA
Prostate adenoma( benign hyperplasia)	Prophylactic diagnosis for men over 45 years of age
Monitoringongoing treatment of adenoma or cancers	Differential diagnosis of cancer, prostatitis, adenomas
Control of treatment of previously identifiedMalignant processes

Preparation for putting on the level of prostate-specific antigen in the blood is influenced by many factors, not all of them are associated with cancer. PSA screening for prostate cancer, in addition to being useful for early detection of tumors in the early stages of the disease, has a number of potential risks, including:

• misinterpretation of diagnostic results;
• complications caused by a biopsy, based on erroneous test results;
• false biopsy data( positive), which serve as an excuse for prescribing treatment if there is no need for it;
• side effects of the prescribed treatment( erectile dysfunction, urinary incontinence, cardiovascular pathology, etc.).

To avoid misinterpretation of the results of laboratory tests, the preparation for the analysis of PSA in men should be carried out in strict accordance with established rules, which include:

• abstinence from sexual activity at least 48 hours before the test( ejaculation leads to an increase in serum PSAblood);
• for 3-4 days before the diagnosis adhere to a special diet( refuse fried, spicy, fatty foods, exclude alcoholic beverages and liquids containing nutrients);
• not less than 3 days to refrain from a massage of the prostate( contributes to a pronounced increase in the level of PSA);
• does not undergo transrectal ultrasound at least a week before the blood is given for analysis( cystoscopy does not have a significant effect on the PSA level, so there is no restriction on its conduct);
• to abandon any physical exertion for a few days before the diagnosis( riding a bicycle, a horse, strength training);
• pass PSA screening no earlier than 6 months.after surgery on the prostate( transurethral resection).

How to take the

test If the preliminary preparation for blood testing for PSA analysis was carried out in accordance with all the recommendations, the results of the study will be more likely to reflect the real level of the antigen. To increase the effectiveness of the diagnosis, follow the rules for taking a blood test for PSA on the day of sampling of biological material, which includes the following provisions:

• diagnosis is carried out on an empty stomach( PSA level does not fluctuate much during the day, but it is recommended to donate blood in the morning after a 10-hour fasting);
• immediately before the procedure must be completely relaxed;
• a complete cessation of smoking should occur no later than one hour before blood sampling;
• before giving blood should avoid physical or emotional stress;
• should refrain from taking medication;
• before the procedure you can drink only clean water.

Blood on the PSA in a volume of 5-10 ml is taken from the vein on the elbow. Laboratory studies using enzyme immunoassay are performed for 1 day, after which the results are transmitted to the doctor for interpretation. If the data obtained as a result of the primary analysis cause doubts about their reliability, a re-delivery of blood is prescribed. To ensure the accuracy of the reanalysis of the PSA, the biomaterial sampling should occur at the same time interval as the first time.

Decoding of PSA analysis in men by age

The PSA rate in men is determined based on the data of long-term observations, and is based on the incidence of oncology in men with different serum markers for the concentration of oncomarker. The opinions of specialists regarding the normal level of PSA are divided - an average norm is the concentration of 4 ng / ml, according to other data this figure should not exceed 2.5 ng / ml.

In view of the fact that the next step after the detection of a high antigen content is a histological examination of the prostate tissue( and this is a serious interference in the structure of the gland), the doctor should be sure of the expediency of carrying out a biopsy. Recent research in the field of diagnostics indicates the necessity of ranking the limits of PSA in men depending on the age and individual characteristics of the organism. The age criteria for distinguishing normal antigen values ​​are presented in the table:

Age of the male, years	The upper limit of the PSA norm, ng / ml	Indications for the appointment of a biopsy, ng / ml
40-44	2.0-2.3	Above 10ratio of free PSA to total less than 15%)
45-49	2.4-2.7
50-54	2.8-3.2
55-59	3.3-3.7
60-64	3.8-4.4
65-69	4.5-5.1
70-74	5.3-6.0
75-79	6.2-7.0
Over 80	7.2

PSA index

If during the interpretation of the results of a blood diagnosis, Eno high content of prostate-specific antigen in it - the doctor should make a decision about the expediency of sampling prostate tissue for the study. The medical conclusion is influenced by factors such as the difference between normal values ​​and the data obtained during the survey, as well as the PSA index.

With a significant difference between the established values ​​of the antigen norm and the results of the analysis, the probability of a positive biopsy increases. If the PSA level exceeds the limit, but is within 10 ng / ml, the indication for the purpose of the histological examination depends on the index of the prostate-specific antigen( Ipsa), which is calculated by the formula: Ipsa =( free PSA / bound PSA) x100%.

The normal value of the index is 15%.The smaller the ratio of free and bound molecular forms of prostate-antigen - the higher the probability of having malignant neoplasms( at Ipsa less than 10% the probability is 56%, with Ipsa greater than 25%, the probability of cancer does not exceed 8%).The need for biopsy is not available at a high Ipsa. The greatest predictive value of the PSA index is observed when the PSA level reaches 68 ng / ml.

Causes of increased PSA

The basis for the use of PSA tests as measures to prevent the development of prostate cancer is the high sensitivity of the oncomarker to changes that occur in the body during the development of tumor processes. The specificity of the prostate antigen lies in the same reaction( increased concentration in the blood) to irritating factors, not all of which are pathogenic. Thus, an increase in the PSA content in the blood can occur for the following non-pathological reasons related to physiology:

• genetic features( enlarged prostate gland size);
• age-related changes( increase in serum prostate antigen level correlates with age due to an increase in prostate volume due to its benign growth);
• classes in extreme sports related to riding a motorcycle, bicycle, etc.;
• conducted on the eve of the analysis, instrumental, visceral manipulation or surgical intervention in the prostate;
• ejaculation.

Despite the fact that the level of PSA concentration is often monitored for the purpose of detecting a cancer of the prostate, this marker is organ-specific( ie it does not indicate a specific disease, but indicates the presence of abnormalities in a particular organ).In addition to the suspected development of oncology, an increase in the PSA concentration may indicate pathologies such as:

• infectious prostatitis;
• diseases of pelvic organs of infectious nature;
• inflammatory processes developing in the prostate gland( prostatitis);
• adenoma of the prostate;
• ischemia( decreased blood flow parameters) or infarction( atrophy of the gland vessels, in which the blood ceases to circulate normally and oxygenates the tissues) of the prostate.

Is there a decrease in the

index? Under the influence of exogenous and endogenous factors, the level of the prostate-specific antigen can decrease. Reducing the concentration of PSA in the blood is not considered when deciphering the tests, as a sign of abnormalities, and the conclusion about a decrease in the indicator is correlated only with the results of the previous study. The most common causes of PSA decline are:

• decrease in the activity of pathological processes occurring in the prostate gland;
• reception of special medications, which are part of the therapy of urological diseases;
• is a pronounced discrepancy between the body weight of a man and his height( body mass index exceeds 30).

Methods for normalizing the value of

If a diagnosis is found during the diagnosis of abnormalities in the prostate-antigen level from the norm, it is necessary to find out the exact cause of this phenomenon and take steps to eliminate it. Reduce the value of the PSA content in the blood can be natural or with the help of medicines. If the presence of prostate pathologies is confirmed, the doctor develops a treatment technique based on the detected disease.

The antigen concentration can be adjusted by observing a special diet that provides for the failure or restriction in the diet of products that increase the risk of tumor formation. To normalize the value of PSA, you should exclude the consumption of saturated fats( dairy products, butter, fatty meat) and introduce more fruits( garnets), vegetables( tomatoes), berries( grapes) into the diet.

The medical way to reduce the level of a tumor marker is to take medications that are prescribed by a doctor. Drugs that, when used for a long time, are able to lower the concentration of antigen in the blood, belong to the following groups:

• inhibitors of 5-alpha-reductase( Dutasteride and Finasteride) - are used to treat prostatic adenoma, slowing its growth;
• Thiazide diuretics( Arindup, Inspra, Hypothiazide) - drugs for the treatment of hypertension, prolonged use of diuretics affect the level of PSA, lowering it;
• lipid-lowering drugs( Fenofibrate, Cholestyramine, Niacin) - reduce cholesterol and promote normalization of body weight, with prolonged admission can reduce the concentration of prostate-antigen.

National treatment can complement a set of measures aimed at normalizing the content of the oncomarker in the blood. With oncological pathologies, it is effective to include phytopreparations based on medicinal herbs( bitter wormwood, plantain, mint, nettle leaves) or poisonous plants( chaga, aconite, amanita, hemlock) in the treatment process. To improve the effectiveness of adenoma therapy, beekeeping products, flax seeds and nuts are used. With the prostatitis it is useful to eat pumpkin seeds.

Price

In the presence of indications for determining the level of PSA in the blood, the doctor prescribes the appointment for the delivery of the analysis. Biomaterial sampling is carried out in the diagnostic center, its research takes place in the laboratory. Services for the definition of oncomarkers are provided by medical institutions that have a documented right to carry out activities in the field of health care. The average prices for the procedure( excluding the cost of sampling biomaterial) in Moscow are given in the table:

Analysis	Diagnostic Center	Cost of procedure, rub.
prostate specific antigen common	Center for Molecular Diagnostics	610
Invitro	610
Female Medical Center	650
Mobilmed	415
On Clinic	590
prostate specific antigen free	Invitro	610
Mobilmed	515
On Clinic	550
PSA index calculation	Molecular Diagnostics Center	950
Female Medical Center	950
Mobilmed	800

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