PSA (prostate specific antigen)

 

Indications:

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.

Principle:

Prostatic specific antigen is a glycoprotein secreted by the prostate.

PSA (prostate specific antigen)Technique:

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.

Results:

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.

Cost:

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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