What is free prostate-specific antigen?

Free prostate-specific antigen is a substance secreted by prostate epithelial cells. It is a protein belonging to the kininase family. It is mainly found in prostate fluid and semen, and its content in human serum is very low. The main function of prostate-specific antigen is to prevent semen from coagulating. Therefore, the analysis of this substance is the first choice marker for the diagnosis of prostate cancer. It has positive clinical significance. Through the diagnosis of prostate-specific antigen, it can be judged whether the patient has prostate cancer. This can play a very important role in the prevention and treatment of diseases. When collecting blood samples, you should also understand some precautions, which will help the accuracy of diagnosis.

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.

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.