PSA (prostate specific antigen)



Health Care

The dosage of the circulating antigen secreted by prostate glandular cells can detect a cancer, to assess the stage to follow the change.

Found in any other tissue, its rate is in any prostatic disease: whether adenoma, cancer, or prostate.


Prostatic specific antigen is a glycoprotein secreted by the prostate.

PSA (prostate specific antigen)

Sampling 5 mL of blood in a dry tube.

The assay method is radioimmunoassay or enzyme immunoassay.

The examination should be performed in the morning, in a strictly fasting patient.


The results are variable depending on the assay techniques and the patient’s age.

This rate also increases in the presence of a prostate adenoma.

Normal values:

– Less than 50 years: 2.5 ng / mL;

– 50 to 59 years: 3.5 ng / mL;

– 60 to 69 years: 4.5 ng / mL;

– 70 to 79 years: 6.5 ng / mL.

To bring the rate to prostate volume, it was proposed to compare this volume, appreciated by ultrasound, found the rate, then with a threshold value to 0.15.

In order to diagnose a cancer, three successive assays are performed in the same laboratory, three months apart.

An increase greater than or equal to 20% of an assay to another is so significant.

Part of PSA exists in free form (about 10%), the report PSA / free PSA is increased in case of adenoma and decreased in cancer.

A free PSA / total PSA is less than 0.15 and for a cancer.

Reported clinical and radiological data, the PSA allows to decide what to do, for example, decide an ultrasound-guided biopsy.

When cancer is diagnosed, a PSA greater than 50 mcg / mL fears lymph node involvement, and greater than 100 mcg / mL metastasis.

Postoperatively, in case of radical prostatectomy, the rate should be undetectable.

The examination may be useful to detect drug treatment failure, when the PSA increases chemotherapy, for example.


B70, 105 or 140.

Practical advice:

To avoid a possible source of error, a PSA assay should be performed at least 10 days after a rectal examination or intrarectal radiological exploration.

For people from the Caribbean, the high incidence of this cancer is that PSA levels should be regularly carried out as screening.

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