What does prostate specific antigen mean?

It is well known that the prostate is an essential organ in the male urinary system. However, as men age, the prostate will always have one or another disease problem. For example, relatively common diseases include prostate hyperplasia and prostatitis. However, prostate cancer is a very serious malignant tumor problem of the urinary system. So what does prostate-specific antigen mean?

Prostate specific antigen (PSA) is secreted by prostate epithelial cells and belongs to the kininase family of proteins. It exists in prostate tissue and semen, and its content in normal human serum is extremely low. PSA exists in serum mainly in three forms: ① free PSA (fPSA), accounting for 10% to 30% of total PSA (tPSA); ② PSA combined with α1-antichymotrypsin to form a complex (PSA-ACT); ③ PSA combined with α2-macroglobulin to form a complex (PSA-α2M). The latter two are also called complexed PSA (cPSA). The main physiological function of PSA is to prevent semen from coagulation. It has extremely high tissue and organ specificity and is currently the preferred marker for diagnosing prostate cancer.

Clinical significance

If serum tPSA and fPSA are elevated, but tPSA/fPSA is decreased, then the diagnosis of prostate cancer should be considered to improve the specificity and accuracy of the diagnosis. Slight elevations in serum tPSA and fPSA may also be seen in prostatitis, prostatic hypertrophy, nephritis, prostatic polyps, and diseases of the urogenital system. When tPSA or fPSA is used alone to diagnose prostate cancer, the influence of benign prostate diseases cannot be ruled out.

Normal value reference range

Total prostate-specific antigen (tPSA): <4.0ng/ml; free prostate-specific antigen (fPSA): ml; fPSA/tPSA: >0.25.

Notes

1. Prostate massage, prostate biopsy, rectal examination, indwelling catheter, cystoscopy, etc. should be avoided before blood specimen collection.

2. The PSA values ​​measured by different methods are different and cannot be mixed.

3. For prostatitis, PSA should be measured 8 weeks after symptoms disappear.

4. Long-term cycling can easily lead to elevated serum PSA levels.

5. Hormone therapy can affect the expression of PSA and reduce PSA levels.

6. Blood samples should be centrifuged within 3 hours of collection and the serum should be refrigerated for no more than 24 hours.

7. Age has an impact on serum PSA levels, which tend to increase with age.

Check the population

1. Men aged 50 years and above with lower urinary tract symptoms.

2. Men with a family history of prostate cancer.

3. Men with abnormal digital rectal examination, clinical manifestations (such as fractures, bone pain, etc.) or abnormal imaging.

4. Patients who have been diagnosed with prostate cancer also need to have their serum PSA tested regularly during follow-up visits after treatment.