PSA Test: What It Is and What It Shows

PSA (prostate-specific antigen) is a protein produced by the prostate gland. A PSA blood test measures its concentration and is used as a prostate tumor marker. Below are definitions, indications, preparation, and the limits of the method.

1. What PSA is and where it is produced

Prostate-specific antigen is an organ-specific protein of the prostate gland: it is produced by both normal and tumor cells of the ducts of the prostate glands. The gland is located beneath the bladder and produces a thick fluid that mixes with sperm and forms seminal fluid.

Normally, a small amount of PSA enters the seminal secretion and ejaculate, and only a negligible amount enters the blood. A low PSA concentration in the blood is normal. The marker is organ-specific: it points to prostate tissue, but not to a specific disease.

2. Why a PSA blood test is ordered

The test is used to screen for prostate cancer — to look for signs of the disease before symptoms appear — to evaluate men with prostate-related complaints, and to monitor treatment of a known prostate disease, including cancer. Reasons include frequent or painful urination, blood in the urine or seminal fluid, pain in the pelvis and back, and erection problems.

The risk of prostate cancer increases after age 50, is higher with a family history, in Black men — in whom the disease occurs more often, at a younger age, and in a more severe form — and with a defective version of the BRCA2 gene. The age at which to start screening is debated: different organizations cite ages from 45 to 55–69 years; in documents from the Russian Ministry of Health, the PSA test is included in the health check-up at ages 45, 50, 55, 60, and 64.

3. Total and free PSA: what the difference is

In blood serum, PSA is present in free form and in bound forms — with α-1-antichymotrypsin and with α-2-macroglobulin. Routinely, free PSA and PSA bound to α-1-antichymotrypsin are measured: their sum makes up total PSA.

4. What can raise PSA levels

A high PSA is possible with prostate cancer, benign prostatic hyperplasia, prostatitis — inflammation of the gland — other common prostate problems, urinary tract infections, and the use of certain medications. The level can also be temporarily raised by certain activities within 48 hours before the test (see preparation below). The test itself does not show the cause of the abnormality: the same result is possible with a tumor and with a non-tumor process.

5. How to prepare for the test and how to read the result

Blood is drawn from a vein, and the procedure takes a few minutes. Within 48 hours before the test, the result can be raised by:

• anal sex and ejaculation
• exertion that causes shortness of breath
• cycling

You can eat and drink as usual. After a urinary tract infection, you should wait 4–6 weeks from the time it resolves. Tell the doctor about medications you are taking, but do not stop them on your own.

The result is usually ready in 1–2 weeks.

There is no single normal PSA level. As a guide: up to 4 ng/mL is considered normal, which corresponds to a low incidence of prostate cancer at such a value; according to other data, the upper limit of normal is no higher than 2.5 ng/mL. A value above 50 ng/mL is associated with a high risk of distant metastasis; above 100 ng/mL reliably indicates distant metastases. Reference limits differ by country and laboratory. If the result is elevated, a repeat test is offered; if the elevation persists, referral to a specialist for biopsy and MRI is discussed.

6. Limitations of the test and when a urologist consultation is needed

The test does not distinguish between a tumor and a non-tumor cause of the elevation. The only way to determine the cause is a prostate biopsy, which carries risks: bleeding at the sampling site, blood in the seminal fluid or urine, infection, and difficulty urinating. Screening leads to overdiagnosis: some tumors grow slowly and do not affect health, whereas treatment is associated with erectile dysfunction and urinary and fecal incontinence. In 30% of patients with elevated PSA, prostate cancer is confirmed by biopsy.

A urologist consultation is needed for elevated PSA, urinary symptoms, blood in the urine or seminal fluid, pain in the pelvis and back, urinary incontinence, and also before deciding on screening.

An elevated PSA by itself is not a reason to call an ambulance. 103 or 112 are needed for a life-threatening condition; discuss other complaints with a urologist.

This material is for reference: it describes the method and its limits, but does not replace a doctor's consultation.

This content is for reference and does not replace a doctor's consultation. Medical disclaimer