Prostatic specific antigen in the blood
Last reviewed: 23.04.2024
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Reference values of prostatic specific antigen in blood serum: men under 40 years - up to 2.5 ng / ml, after 40 years - up to 4 ng / ml. The half-life is 2-3 days.
Prostatic specific antigen (PSA) is a glycoprotein secreted by the cells of the epithelium of the tubules of the prostate. Due to the fact that PSA is formed in the paraurethral glands, only very small amounts of it can be found in women. A significant increase in the level of the prostatic specific antigen in the serum is sometimes found in prostatic hypertrophy, as well as in inflammatory diseases of the prostate gland. At a separation point of 10 ng / ml, the specificity for benign prostatic diseases is 90%. Finger rectal examination, cystoscopy, colonoscopy, transurethral biopsy, laser therapy, urinary retention can also cause a more or less pronounced and prolonged rise in the level of the prostatic specific antigen. The effect of these procedures on the level of the prostatic specific antigen is most pronounced on the day after their administration, and most significantly - in patients with prostatic hypertrophy. The investigation of the prostatic specific antigen in such cases is recommended not earlier than 7 days after the above procedures.
The concentration of the prostatic specific antigen tends to increase with age, so the concept of "permissible upper limit of the norm" for different age groups is different.
Admissible "normal" values of the prostatic specific antigen depending on the age
|
Age, years | ||||
|
40-49 |
50-59 |
60-69 |
70-79 | |
|
PSA, ng / ml |
2.5 |
3.5 |
4,5 |
6.5 |
The study of prostatic specific antigen is used to diagnose and monitor the treatment of prostate cancer, in which its concentration increases, as well as to monitor the condition of patients with prostatic hypertrophy for the purpose of detecting cancer of this organ as early as possible. The concentration of the prostatic specific antigen in the blood above 4 ng / ml is found in about 80-90% of cancer patients and in 20% of patients with prostatic adenoma. Therefore, an increase in the level of the prostatic specific antigen in the blood does not always indicate the presence of a malignant process.
An increase in the concentration of prostatic specific antigen in the blood in patients with prostate cancer is faster than in patients with benign hyperplasia. The total prostatic specific antigen more than 50 ng / ml indicates extracapsular invasion in 80% of cases and lesion of regional lymph nodes in 66% of patients with prostate cancer. There is a correlation between the concentration of the prostatic specific antigen in the blood and the degree of malignancy of the tumor. Currently, it is believed that an increase in the prostatic specific antigen to 15 ng / ml and above, together with a low-grade type of tumor, in 50% of cases indicates extracapsular invasion and should be taken into account when determining the amount of surgery. At values of a prostatic specific antigen from 4 to 15 ng / ml, the incidence of cancer is 27-33%. The values of prostatic specific antigen above 4 ng / ml are revealed in 63% of patients with prostate cancer of stage T1 and in 71% of patients at stage T2. When assessing the level of the prostatic specific antigen in the blood, you need to focus on the following indicators:
- 0-4 ng / ml is the norm;
- 4-10 ng / ml - suspected of prostate cancer;
- 10-20 ng / ml - a high risk of prostate cancer;
- 20-50 ng / ml - the risk of disseminated prostate cancer;
- 50-100 ng / ml - a high risk of metastases to the lymph nodes and distant organs;
- more than 100 ng / ml - always metastatic prostate cancer.
Monitoring the concentration of the prostatic specific antigen provides an earlier detection of relapse and metastasis than other methods. At the same time, changes even within the limits of the norm are informative. After total prostatectomy PSA should not be detected, its detection indicates residual tumor tissue, regional or distant metastases. The level of residual concentration lies in the range from 0.05 to 0.1 ng / ml, any excess of this level indicates a relapse.
Prostatic specific antigen is determined not earlier than 60-90 days after surgery due to possible false positive results due to the incomplete clearance of the prostatic specific antigen present in the blood prior to prostatectomy.
With effective radiation therapy, the concentration of the prostatic specific antigen in the blood should decrease by an average of 50% during the first month. Its concentration in the blood decreases and with the performance of effective hormonal therapy.
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