RBC - urine
Key points
- The RBC urine test measures the number of red cells in a given volume of urine.
- To obtain a clean-catch sample, men or boys should clean the head of the penis.
- Open a urine collection bag (a plastic bag with an adhesive paper on one end), and place it on the infant.
- No special preparation is necessary for this test, but if the collection is being taken from an infant, a couple of extra collection bags may be necessary.
Alternative names
Red blood cells in urine; Hematuria test
Definition
The RBC urine test measures the number of red cells in a given volume of urine.
How the test is performed
Child or adult:
Collect a "clean-catch" (midstream) urine sample. To obtain a clean-catch sample, men or boys should clean the head of the penis. Women or girls need to wash the area between the lips of the vagina with soapy water and rinse well. As you start to urinate, allow a small amount to fall into the toilet bowl to clear the urethra of contaminants. Then, put a clean container under your urine stream and catch 1 to 2 ounces of urine. Remove the container from the urine stream. Cap and mark the container and give it to the health care provider or assistant.
Infant:
Thoroughly wash the area around the urethra. Open a urine collection bag (a plastic bag with an adhesive paper on one end), and place it on the infant. For males, the entire penis can be placed in the bag and the adhesive attached to the skin. For females, the bag is placed over the labia. Diaper as usual over the secured bag.
This procedure may take a couple of attempts - lively infants can displace the bag, causing the specimen to be absorbed by the diaper. The infant should be checked frequently and the bag changed after the infant has urinated into the bag. The urine is drained into the container for transport to the laboratory.
How to prepare for the test
No special preparation is necessary for this test, but if the collection is being taken from an infant, a couple of extra collection bags may be necessary.
How the test will feel
The test involves only normal urination, and there is no discomfort.
Normal Values
Normal Values are less than, or equal to 4 RBC/HPF. Normal value ranges may vary slightly among different laboratories.
Note: RBC/HPF = red blood cells per high power field (a microscopic exam).
What abnormal results mean
Abnormal results indicating greater-than-normal numbers of red blood cells in the urine may indicate:
- Glomerulonephritis
- Interstitial nephritis
- Acute tubular necrosis
- Pyelonephritis
Written and revised by
David Cohen, M.D.
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