What is the Free to Total ratio?

The PSA test measures the level of prostate-specific antigen in the blood, a protein produced by both cancerous and non-cancerous tissue in the prostate. PSA exists in two main forms in the blood:

• Free PSA: The PSA that is not bound to proteins in the blood.
• Total PSA: The sum of both free PSA and PSA bound to blood proteins.

The Free to Total PSA ratio is the percentage of free PSA compared to the total PSA. This ratio is expressed as a percentage and can provide additional information beyond the total PSA level alone.

PSA tests by GFCT always test for Free to Total when necessary. Please note that not all test providers will offer this.

The Importance of the Free to Total Ratio

The Free to Total PSA ratio is particularly valuable in distinguishing between prostate cancer and other non-cancerous conditions. Research has shown that men with prostate cancer tend to have a lower percentage of free PSA compared to those with benign conditions like BPH. Here's why this test is significant:

Diagnostic Accuracy

While elevated total PSA levels can indicate prostate cancer, they can also be caused by benign conditions. A lower Free to Total PSA ratio increases the likelihood of prostate cancer, whereas a higher ratio suggests a benign condition.

Risk Assessment

The ratio is used to assess the risk of prostate cancer. For instance, a Free to Total PSA ratio of less than 10% is associated with a higher risk of prostate cancer, while a ratio above 25% indicates a lower risk.

Next Steps

This ratio helps physicians decide whether a prostate biopsy is necessary. Men with lower ratios are more likely to be referred for a biopsy, whereas those with higher ratios might be monitored with regular PSA testing.