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Prostate-specific antigen in the blood
Medical expert of the article
Last reviewed: 05.07.2025
Reference values of prostate-specific antigen in blood serum: men under 40 years old - up to 2.5 ng/ml, after 40 years old - up to 4 ng/ml. Half-life is 2-3 days.
Prostate-specific antigen (PSA) is a glycoprotein secreted by the epithelial cells of the prostate gland tubules. Since PSA is formed in the paraurethral glands, only very small amounts of it can be detected in women. A significant increase in the level of prostate-specific antigen in the serum is sometimes detected in hypertrophy of the prostate gland, as well as in its inflammatory diseases. At the cutoff point of 10 ng / ml, the specificity in relation to benign diseases of the prostate gland is 90%. Digital rectal examination, cystoscopy, colonoscopy, transurethral biopsy, laser therapy, urinary retention can also cause a more or less pronounced and long-term increase in the level of prostate-specific antigen. The effect of these procedures on the level of prostate-specific antigen is most pronounced the next day after their implementation, and most significantly - in patients with prostate hypertrophy. In such cases, it is recommended to conduct a prostate-specific antigen test no earlier than 7 days after the above procedures.
The concentration of prostate-specific antigen tends to increase with age, so the concept of the “acceptable upper limit of normal” is different for different age groups.
Acceptable "normal" values of prostate-specific antigen depending on 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 prostate-specific antigen is used for diagnostics and monitoring of prostate cancer treatment, in which its concentration increases, as well as for monitoring the condition of patients with prostate hypertrophy in order to detect cancer of this organ as early as possible. The concentration of prostate-specific antigen in the blood above 4 ng/ml is found in approximately 80-90% of patients with cancer and in 20% of patients with prostate adenoma. Therefore, an increase in the level of prostate-specific antigen in the blood does not always indicate the presence of a malignant process.
The increase in the concentration of prostate-specific antigen in the blood of patients with prostate cancer occurs faster than in patients with benign hyperplasia. Total prostate-specific antigen over 50 ng/ml indicates extracapsular invasion in 80% of cases and involvement of regional lymph nodes in 66% of patients with prostate cancer. There is a correlation between the concentration of prostate-specific antigen in the blood and the degree of tumor malignancy. Currently, it is believed that an increase in prostate-specific antigen to 15 ng/ml and higher together with a low-differentiated tumor type in 50% of cases indicates extracapsular invasion and should be taken into account when determining the extent of surgical intervention. With prostate-specific antigen values from 4 to 15 ng/ml, the frequency of cancer detection is 27-33%. Prostate-specific antigen values above 4 ng/ml are detected in 63% of patients with stage T1 prostate cancer and in 71% of patients with stage T2. When assessing the level of prostate-specific antigen in the blood, it is necessary to focus on the following indicators:
- 0-4 ng/ml - normal;
- 4-10 ng/ml - suspected prostate cancer;
- 10-20 ng/ml - high risk of prostate cancer;
- 20-50 ng/ml - risk of disseminated prostate cancer;
- 50-100 ng/ml - high risk of metastases to the lymph nodes and distant organs;
- more than 100 ng/ml - always metastatic prostate cancer.
Monitoring the concentration of prostate-specific antigen ensures earlier detection of relapse and metastasis than other methods. Moreover, changes even within the normal range 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 is in the range from 0.05 to 0.1 ng/ml; any excess of this level indicates a relapse.
Prostate-specific antigen is determined no earlier than 60-90 days after surgery due to possible false-positive results due to incomplete clearance of prostate-specific antigen present in the blood before prostatectomy.
With effective radiation therapy, the concentration of prostate-specific antigen in the blood should decrease by an average of 50% during the first month. Its concentration in the blood also decreases with effective hormonal therapy.
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