Prostate Specific Antigen (Free) PSA

The prostate is a small walnut-shaped gland located just below the bladder and in front of the rectum in males. It produces a protein called prostate-specific antigen (PSA) that is mainly found in semen (also produced by the prostate gland) and is present in small amounts in the bloodstream of all men. It helps liquify the semen and facilitates sperm motility during ejaculation in males.

The Prostate Specific Antigen (Free) PSA test helps determine the level of free PSA in men. Unlike total PSA, which measures the total amount of PSA in the bloodstream (both free and bound to proteins), this test specifically measures the proportion of PSA that is not bound to proteins. Your doctor may recommend the Prostate Specific Antigen (Free) PSA test if you experience symptoms such as difficulty passing urine, straining or taking a long time while urinating, terminal dribbling, passing urine more frequently than usual, especially during the night, or blood in the urine. This test is also especially recommended in men over the age of 50 or at an earlier age (>40 years) for those at higher risk due to family history or other risk factors such as a high-fat diet.

Fasting is not required for this test; you may eat and drink as per your daily routine. However, talk to your doctor if you take any prescription or over-the-counter medications, as some may interfere with your test results. It is advised to avoid sexual intercourse for at least 48 hours before the test, as semen release (ejaculation) can increase your PSA levels, leading to inaccurate results. The Prostate Specific Antigen (Free) PSA test should also not be done immediately after cystoscopy, digital rectal examination (DRE), prostatic massage, indwelling catheterization, ultrasonography, and prostate needle biopsy as they too may falsely elevate PSA levels

Free PSA levels alone do not have much role in diagnosis and management. However, the ratio of free PSA to total PSA (percent free PSA) is an important indicator in the detection of prostate cancer. In individuals with elevated total PSA levels  (4- 10 ng/ml), a high percent free PSA suggests a benign cause, while low percent free PSA values are more indicative of prostate cancer. Furthermore, while total PSA is used as a sensitive marker for prostate cancer recurrence after treatment, the Prostate Specific Antigen (Free) PSA test may not have much role in post-treatment monitoring.

Talk to your doctor about your specific test results. Regardless of levels, PSA values are not absolute evidence of the presence or absence of disease. Further diagnostic tests, such as digital rectal examination (DRE) and biopsy, may be needed to confirm or rule out the possibility of cancer. Values obtained with different assay methodologies should not be used interchangeably. It is recommended that only one assay method be used consistently to monitor the course of therapy.