Scientific editor: M. Merkusheva, PSPbGMU them. Acad. Pavlov, general medicine.
March, 2019.
Synonyms: Total PSA, prostate specific antigen common, Prostate-specific antigen total, PSA total.
Prostate-specific antigen (PSA) is secreted by the epithelial tissues of the prostate. Its purpose - to natural semen liquefaction. Therefore, normal in healthy men the PSA blood is always present, but the concentration should not exceed the established normal values. Otherwise, you can talk about the development of pathological changes in the structure and functioning of the prostate.
Research on total PSA in plasma is the most reliable and indicative for the diagnosis of benign and malignant prostate disease and other pathological changes (inflammation, infection, reproduction pathogens, and so on. d.). The main objective of the study is the diagnosis of cancer.
Overview
Prostate specific antigen is a glycated protein, a small part, which after production prostate released into the bloodstream where circulates in two states - free and bound. The totality of these two fractions and a total PSA. Their ratio is about 9: 1. In prostate carcinoma (cancer) in the blood level rises bound form, which leads to a reduction ratio between free and total PSA.
Increasing the level of antigen in the plasma is observed in the presence of benign or malignant diseases and inflammatory infectious processes, mechanical and thermal injuries, and after some treatment and diagnostic procedures. Timed release component causes ejaculation, after which it was again stabilized level after 2 days.
With age, total PSA concentration increases, and the percentage of free fraction, on the contrary, reduced. PSA test is recommended annually conducts men older than 50 years (risk group by age). Early screening (to 40) is indicated in patients with a history burdened (malignant processes from their native in the first line).
Interpretation of test results is always carried out in conjunction with other diagnostic studies: analysis of biological fluids, rectal palpation of the prostate MRI, biopsy, ultrasound, X-rays and so on. d.
PSA is able to inhibit the migration, proliferation and invasion of endothelial cells in tumors and therefore its slow growth. This function can be partially explained by naturally slow the progression of prostate cancer1.
testimony
The main purpose of the determination of total PSA in plasma - screening for prostate cancer (PCa), including in the form of an additional marker on the results of rectal examination.
Also a study conducted to determine the stage of the cancer process, the probability of recurrence or remission metastasis, the overall forecast, which is important in the first 6-18 months of therapy, the decision to hold Prostate biopsy. The test allows to verify the effectiveness of the selected treatment regimen (chemotherapy, drug or radiotherapy, hormone therapy, physical therapy, surgery, and so on. D.).
In some cases, the assigned analysis:
- Suspected benign or malignant processes prostate inflammation and structural changes in its tissue;
- Age older than 50 years (mandatory screening);
- Age from 40 years (in the presence of close relatives with cancer of the pelvic organs);
- Prostatic hyperplasia;
- The patient's complaints of shortness, painful and frequent urination;
- Increasing the size, structure and consistency of the prostate according rectal examination or ultrasound.
Interpretation of the results of the analysis holds oncologist, surgeon, urologist, the therapist.
Normal values of total PSA
Important! Rates can vary depending on the reagents and equipment used in a particular laboratory. That is why the interpretation of results it is necessary to use standards adopted in that laboratory, where medical tests. It is also necessary to pay attention to the units.
For a long time it was believed that the total PSA should be in the range of from 0 to 4 ng / ml. But according to recent decades medical statistics, malignant process can begin and progress at lower PSA performance (up to 2.5 ng / ml).
The normal value for total PSA test to date are shown in Table2:
| Age, years |
Norm total PSA, ng / ml |
| 40-49 | 0-2.5 |
| 50-59 | 0-3.5 |
| 60-69 | 0-4.5 |
| 70-79 | 0-6.5 |
Analysis of the total PSA is always combined with the definition of free-form it. The latter is characterized by the fact that does not bind to other proteins and circulates in its original form (as epithelial cells of the prostate was performed).
Typically, one sample analysis being identified all forms of circulating PSA, then set their mathematical ratio in percentage. This information is especially necessary in situations when total PSA is 10 ng / ml, which can be due to increased risk of severity of inflammation in the prostate, the appearance of malignant neoplasms. If the value ratio free and total PSA over 25% oncologist not diagnose malignant disease, while the ratio is below 15% is an additional marker to the definition of cancer.
To evaluate pathological risks, namely, when the threshold is exceeded PSA 4 ng / ml, calculated relation (index) necessary indicators according to the formula:
free PSA / Total PSA * 100%
Result in more than 25% indicates benign process or favorable prognosis of various inflammatory diseases, prostate structural changes, and so on. D. Values of up to 10% indicate a high risk of developing cancer.
Important! Interpretation of the results is always carried out comprehensively. An accurate diagnosis on the basis of only one analysis impossible.
Elevated total PSA
The probability of detecting cancer, depending on the excess of the norm3:
- to 10 ng / ml - suspicion of prostate cancer;
- 10-20 ng / ml - high risk for prostate cancer;
- 20-50 ng / ml - the risk of disseminated prostate cancer;
- 50-100 ng / ml - a high risk of metastasis to lymph nodes and distant organs;
- more than 100 ng / ml - always metastatic prostate cancer.
Other conditions in which increased levels of total PSA:
- Myocardial ischemia or prostate;
- Prostate hyperplasia tissue, Change in structure or volume;
- Diseases of the genito-urinary organs;
- Prostatitis in acute or chronic form;
- Benign neoplasms (cyst adenomas, polyps, etc...);
- Cancerous processes (80%).
Why is the wrong result
False positive test results may provoke the following factors:
- recent manipulation of the prostate (massing, rectal examination and palpation, transrectal ultrasound, biopsy etc.);
- cystoscopy, Bladder catheterization;
- urinary tract infection;
- intense physical stress (cycling, horseback riding);
- sexual intercourse and ejaculation;
- taking certain medications (allopurinol, finasteride, cyclophosphamide, methotrexate, androgen antagonists).
Analysis of PSA administered not earlier than one week after the removal of said factors.
decrease in value
Reduced level of specific antigen is not talking about rejection and about the minimum level of malignancy risk. The examination in dynamics reduction of total PSA is less than 2 ng / ml indicates the effectiveness of therapeutic measures and favorable prognosis.
In men, obese total PSA level may be lowered due to the increase in the ratio of estradiol to testosterone and hemodilution (decrease in the number of red blood cells in plasma associated with an increase in the total volume plasma)4.
Preparation for the donation of blood for PSA
The biomaterial for the analysis: the venous blood.
Method biomaterial sampling: the antecubital vein venipuncture.
Special conditions: the procedure is carried out strictly on an empty stomach, but is not tied to a specific time of day.
Additional requirements
On the eve of venipuncture is not recommended:
- use sharp and / or fatty foods;
- drinking alcohol and / or energy;
- exposed to emotional stress;
- overstrain physically; ride a bike
- have sex (abstinence should ideally be at least three days);
2-3 hours before the procedure is prohibited to:
- smoking or chewing tobacco;
- taking medication.
At the concentration of PSA in the blood affects the prostate stimulation, so the test was administered 7-9 days after the following studies:
- DRE / prostate massage;
- colonoscopy;
- Ultrasound (transrectal);
- cystoscopy;
- bladder catheterization;
- biopsies of pathological tissues (6 weeks) and t. d.
Important! Analysis of total PSA is not carried out in the presence of acute diseases of the genitourinary system.
According to the results of the test to assess the dynamics of the disease, so PSA is determined repeatedly and always combined with other invasive and non-invasive methods of examination.
sources:
- 1. Fortier AH; Nelson BJ. Antiangiogenic activity of prostate-specific antigen. - Journal of the National Cancer Institute, 1999.
- 2. Stanley A Brosman, MD. Prostate-Specific Antigen Testing. - Medscape, 2015.
- 3. A.A.Kishkun, prof. Manual for the laboratory diagnosis methods - GEOTAR-Media, 2007.
- 4. Adel T Aref, Andrew D Vincent. The Inverse Relationship Between Prostate Specific Antigen (PSA) and Obesity. - Endocrine-related cancer, in 2018.
