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RBC - urine

Definition

The RBC urine test measures the number of red blood cells in a urine sample.

Alternative Names

Red blood cells in urine; Hematuria test; Urine - red blood cells

How the test is performed

A clean-catch urine sample is needed.

To obtain a sample, boys and men should wipe the head of the penis clean. Girls and women need to wipe between the vaginal "lips" (labia) with soapy water and rinse well. Your doctor may give you a special clean-catch kit that contains a cleansing solution and sterile wipes.

Urinate a small amount into the toilet bowl to clear the urethra of any contaminants. Then, collect a sample of urine in a clean or sterile container. About 1 - 2 ounces of urine is needed for a test. Remove the container from the urine stream without stopping the flow. You may finish urinating into the toilet bowl. Take the sample to the lab.

For infants, the genital area is cleaned and dried, and then a collection device is attached to collect the urine. If you are asked to collect the urine, be sure the collection device is attached securely to prevent leakage. After your baby has urinated, the urine (at least 20 cc) is placed in a sterile container.

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.

Why the test is performed

Normal Values

Normal values are 4 red blood cells per high power field (RBC/HPF) or fewer. Normal value ranges may vary slightly among different laboratories. Talk to your doctor about the meaning of your specific test results.

What abnormal results mean

Greater than normal numbers of red blood cells in the urine may indicate:

• Acute tubular necrosis
• Cystitis (bladder infection)
• Glomerulonephritis
• Interstitial nephritis
• Pyelonephritis (kidney infection)
• Kidney trauma
• Kidney tumor
• Kidney stones
• Menstrual bleeding
• Prostatitis

Additional conditions under which the test may be performed:

• Alport syndrome
• Complicated UTI (pyelonephritis)
• Membranoproliferative GN II
• Kidney vein thrombosis

What the risks are

There are no risks.

Special considerations

References

Bazari H. Approach to the patient with renal disease. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 115.