Serum Creatinine
In men with symptoms, blood tests can measure a substance called serum creatinine, which is a marker for kidney trouble. Kidney problems exist in an average of 13.6% of BPH patients. Studies have reported rates as high as 30% and as low as 0.3%.
PSA Test for BPH and Prostate Cancer
A PSA test measures the level of prostate-specific antigen (PSA) in the patient's blood. It is the standard screening test for prostate cancer. A PSA is recommended annually for all men over 50 years old and for men over 40 who are at high risk for prostate cancer.
BPH itself can also raise PSA levels, but the test has generally been optional for men with suspected BPH. One 2000 study indicated that PSA levels may be good predictors of future prostate growth in men with BPH. In the study, men with the lowest PSA level groups (0.2 to 1.3 ng/mL) had prostate growth rates of only 0.7 mL per year while those in the high PSA groups (3.3 to 9.9) had growth rates of 3.3. mL per year. Other research has detected a specific molecular form of PSA, called BPSA because it may be a specific marker for BPH. Such findings could eventually lead to a shift from focusing on symptoms and flow rates for diagnosis to a more specific and possibly preventive approach.
Certain treatments for BPH, including the drug finasteride (Proscar) and the surgical procedure transurethral resection of the prostate (TURP), can reduce PSA levels and possibly mask the existence of prostate cancer.
A more recent test identifies so-called free PSA, which is found in lower levels when prostate cancer is present and in higher levels with benign prostate hyperplasia. This may be more accurate than total PSA, regardless of whether a man is taking finasteride or not.
Postvoid Residual Urine
One of the important tests for urinary incontinence is the postvoid residual urine volume (PVR), the amount of urine left after urination. Normally, about 50 mL or less of urine is left; more than 200 mL is a definite sign of abnormalities. Measurements in between require further tests. The most common method for measuring PVR is with a catheter, a soft tube that is inserted into the urethra within a few minutes of urination. PVR can also be measured using transabdominal ultrasonography.
Ultrasound
Ultrasound of the prostate does not require a catheter and gives an accurate picture of the size and shape of the prostate gland. Ultrasound is very beneficial when planning surgery and determining treatment options and gauging their effectiveness. Ultrasound may also be used for detecting kidney damage, tumors, and bladder stones. Ultrasound tests of the prostate generally use one of two methods:
- Transrectal ultrasonography (TRUS) uses a rectal probe for assessing the prostate. TRUS is significantly more accurate for determining prostate volume. It can sometimes detect cancer.
- Transabdominal ultrasonography uses a device placed over the abdomen. It can give an accurate measure of postvoid residual urine and is less invasive and expensive than TRUS.
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