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What Are the Causes of WBC & RBC in Urine?

author image Shelly Morgan
Shelly Morgan has been writing and editing for over 25 years for various medical and scientific publications. Although she began her professional career in pharmacological research, Morgan turned to patent law where she specialized in prosecuting patents for medical devices. She also writes about renal disease and hypertension for several nonprofits aimed at educating and supporting kidney patients.
What Are the Causes of WBC & RBC in Urine?
RBCs and WBCs in the urine are symptoms of several different conditions. Photo Credit senior doctor 10 image by Paul Moore from <a href='http://www.fotolia.com'>Fotolia.com</a>

Hematuria refers to the presence of red blood cells (RBCs) in the urine. This is called frank hematuria if the blood is very obvious, and microhematuria if the red blood cells can only be seen under a microscope. The presence of red blood cells in the urine is found either through a dipstick test, or by examining the urine under a microscope.

A special type of white blood cell called a leukocyte is occasionally found in the urine. According to the University of Utah, dipstick urinalysis does not test for white blood cells (WBCs) per se, but for an enzyme called leukocyte esterase. When leukocyte esterase is found, it is a safe presumption that white blood cells are in the urine.

Traumatic Abrasion

Red blood cells in the urine can be caused by some kind of traumatic abrasion of the urinary tract, such as when a urinary catheter is removed or a kidney stone is passed. Such injuries tend to heal quickly. Doctors may not even order a follow-up urinalysis.

Kidney Disease

According to the National Institute of Diabetes, Digestive and Kidney Disease, the persistent presence of red blood cells and white blood cells in the urine can be indicative of kidney disease. Doctors will evaluate information from urine tests in conjunction with information from blood tests to determine if further testing is necessary. If your serum creatinine is normal and your urine protein is not very high, doctors may opt for a strategy of watchful waiting. If these values are extremely out of range, the doctor may order a kidney ultrasound, a kidney biopsy or further blood work to determine the specific nature of the kidney disease.

Urinary Tract Infection

The combined presence of white blood cells and red blood cells in the urine can also suggest a urinary tract infection. The Mayo Clinic reports that if such an infection is present, the patient often experiences other symptoms such as frequent and painful urination, fever, nausea, vomiting and back pain.

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