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Medical Devices

VIDAS fPSA rt Assay - P080008

This is a brief overview of information related to FDA’s approval to market this product.  See the links below to the Summary of Safety and Effectiveness Data (SSED) and product labeling for more complete information on this product, its indications for use, and the basis for FDA’s approval.

Product Name: VIDAS fPSA rt Assay
PMA Applicant:  Biomerieux Inc.
Address:  595 Anglum Road Hazelwood, MO 
Approval Date:
Approval Letter: 

What is it?  The VIDAS fPSA rt Assay is a lab test, used along with digital rectal examination, to help diagnose prostate cancer in men age 50 years and older.  The tests measure how much free prostate-specific antigen (fPSA) is in a man’s blood.  A man’s prostate gland makes prostate specific antigen (PSA).  In his blood, most of the PSA is attached to other substances and is called complexed PSA.  The small portion that is not attached is called fPSA.  Complexed PSA and fPSA together are called total PSA (tPSA).  When cancer develops in a man’s prostate, the amount of tPSA usually increases and the proportion of fPSA to tPSA decreases.  A laboratory tests for both fPSA and tPSA in the same patient sample and calculates the fraction of the tPSA that exists as fPSA.  If the fPSA/tPSA fraction is less than 0.23, there is a significant chance that the man has prostate cancer.  The man then needs to have biopsy (surgical sampling of tissue) of his prostate to diagnose and confirm his prostate condition.

How does it work? 

  • A sample of blood is drawn from the patient and added to chemicals in the Free PSA test.
  • When a specific chemical is added, a light reaction is produced and is measured inside an instrument.
  • The amount of light emitted shows the level of fPSA in the blood.
  • The fPSA level is used with tPSA measured in the same sample to calculate the fraction of tPSA that is fPSA.
  • The Free PSA test can only be used with the Total PSA test from the same company and on the same instrument system.

When is it used?  A man should have this test when he

  • Is 50 years or older, and
  • Has a total PSA value between 4 ng/mL and 10 ng/mL, and His prostate gland has a normal size and texture by a digital rectal examination (DRE).

What will it accomplish?  As a man ages, his prostate has a greater chance of developing cancer and non-cancerous conditions such as benign prostatic hyperplasia.  This test helps the doctor to determine the chances of cancer in a patient and whether a prostate biopsy is needed.  Therefore, this test may help to reduce the number of unnecessary biopsies in men who have tPSA values in the range of 4 ng/mL to 10 ng/mL whose DRE is not suspicious for cancer and are unlikely to have cancer.

When should it not be used?  The test should not be used when the tPSA value is outside 4-10 ng/mL and when the DRE is suspicious or cancer. It should not be used with other company’s total PSA assay to calculate the fPSA/tPSA fraction. A doctor should not diagnose prostate cancer using only the results of the free PSA test. Diagnosis of cancer can confidently be made only by biopsy of the prostate gland.

Additional information:  Summary of Safety and Effectiveness and labeling are available at: 

Page Last Updated: 09/06/2013
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