Laboratory and Other Diagnostic Tests
PSA Testing
The purpose of the prostate-specific antigen (PSA) test, along with the digital rectal examination, is to rule out prostate cancer as the cause of your symptoms – or to raise warning signs that you need to be evaluated further.
The PSA test measures PSA levels in a man’s blood. Most men have low levels of PSA in the blood. Higher than normal levels may indicate that prostate cancer is present. However, about 25 percent to 30 percent of men with elevated PSA levels have other reasons for this result. Higher levels of PSA may be caused by BPH, prostate inflammation, prostate infection, or even age and hereditary factors.
As a result, your doctor should discuss the PSA test with you. If it is negative and you have a digital rectal examination negative for prostate cancer, this is a reassuring result and good evidence that you do not have prostate cancer. You and your doctor can move on to the best strategy for treating your BPH or other diagnosed condition.
However, if the PSA test is positive, it may or may not be due to the presence of prostate cancer. You and your doctor will need to follow through to be sure. Your doctor may recommend repeating the PSA test to see if levels climb higher, take a biopsy of your prostate tissue, or perform other tests, including imaging tests of your prostate.
Because the PSA test registers a false positive in a relatively high percentage of men, it’s best that you and your doctor are prepared for the possibility of a positive test. Because the PSA test can lead to more invasive testing (biopsy), you and your doctor should discuss this possibility. Some variations of the PSA test that have been developed to make PSA results more specific include the measurement of PSA velocity (PSAV), free-total PSA ratio, complexed PSA (cPSA), and PSA density (PSAD).
Urine and Blood Testing
Other laboratory tests that may be useful for the doctor to order include a urinalysis (diagnostic analysis of your urine) to rule out the presence of an infection and blood tests for signs of diabetes (which can also cause nighttime urination), heart disease, or other problems.
Other Laboratory Tests
If the results of the above tests suggest you may have BPH, your health care provider will probably want to perform additional laboratory tests to confirm the diagnosis and determine how severe your condition is. These include:
Urine flow test - measures the amount and strength of urine flow. A rate of 15 milliliters per second or greater is normal. A rate of 10 to 15 milliliters per second is associated with mild to moderate symptoms. A rate of less than 10 milliliters per second may suggest moderate to severe BPH.
Postvoid residue volume test - ultrasound imaging to detect if you can empty your bladder when you urinate.
Ultrasound - an imaging test of your prostate performed by inserting a probe in your rectum to determine the size of the prostate and to detect any blockages or obstructions, such as ones caused by a kidney stone, prostate stone, or tumor.
Cytoscopy - a cytoscope (a lighted probe) is placed into your urethra to look for visible tissue changes in your urethra and urinary bladder.
Urodynamic studies - this involves a series of tests in which a small catheter is threaded through the urethra and into the bladder so that bladder pressure and function can be measured. Your doctor may want to perform this test if he or she suspects your symptoms could be related to a bladder or a neurologic problem.
More extensive imaging of your bladder, urinary tract, and kidneys may be appropriate if your doctor suspects you have urinary tract or kidney damage, or other disorders in addition to BPH. This is not generally necessary if you have no other problems besides BPH causing problems that have not advanced beyond urinary symptoms.