Description of PSA Blood Test
PSA is a protein produced by the prostate. Most of the PSA that the prostate produces is released into the semen, but small amounts are also released into the bloodstream.
Patients with prostate cancer frequently have altered ratios of the two forms of PSA: low leves of free PSA and high levels of cPSA (PSA bound to a protein).
The PSA blood test and digital rectal exam (DRE) are ordered to screen for prostate cancer. If either the PSA or the DRE are found to be abnormal, then the doctor may choose to follow this testing with a prostate biopsy and perhaps imaging tests, such as an ultrasound. If the DRE is normal but the PSA is moderately elevated, the doctor may order a free PSA test to look at the ratio of free to total PSA. This can help to distinguish between prostate cancer and other non-cancer causes of elevated PSA.
The PSA blood test may be ordered during treatment of patients who have been diagnosed with prostate cancer to verify the effectiveness of treatment and at regular intervals after treatment to monitor for cancer recurrence.
Its concentration is measured by means of analysis of a blood sample drawn from the vein in the arm.
Purpose of the PSA Blood test
To meassure the Prostate Specific Antigen (PSA) level in blood in order to screen asymptomatic and symptomatic men for prostate cancer in order to help determine the necessity for a biopsy of the prostate and also in order to monitor the effectiveness of treatment for prostate cancer, or to detect recurrence of prostate cancer.
The PSA blood test was originally developed as a tumor marker to screen for and to monitor prostate cancer. It is a good tool, but not a perfect one. PSA levels are higher in those of African American heritage, and levels tend to increase in all men as they age.
PSA Blood test Reference range values
<= 4.0 mcg/L or could be interpreted as <= 4.0 ng/ml
Abnormal findings
Patients with PSA level greater than 10mcg/L are at an increased risk for prostate cancer.
Levels between 4 and 10 may indicate prostate cancer BPH, or prostatitis. These conditions are more common in the elderly, as is a general increase in PSA levels.