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PSA Standardization

Utilization of Free/Total PSA Ratio11

Slide 13

October 2009

Free PSA can also be measured in serum and increased levels of free PSA were first noted to be associated with benign disease and decreased probability of cancer.  Reporting of the free PSA as a free to total PSA ratio was first approved by the FDA in 1998.  If the ratio is high (>25%) the probability of cancer is greatly decreased, and similarly if the ratio is low (<10%) it indicates a greater probability of cancer. A limitation of this ratio is that most patients will be somewhere in the middle (the gray zone), and this would still lead to biopsies.  Nevertheless, free PSA is used to aid biopsy decisions.

Free/Total Ratio


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