White blood cells are not found in the urine of healthy people. This symptom can be secondary to a number of diseases ranging from easily treated urinary tract infections to chronic kidney disease that ends in renal failure. Since this symptom occurs with so many different diseases, it is essential to consider other symptoms and lab results before jumping to conclusions.
Testing
The presence of white blood cells in the urine can be detected in two ways. According to the University of Utah Mercer School of Medicine, white blood cells are found by examining a urine specimen under a microscope or by dipping an indicator strip into the urine.
Indicator strips react to the presence of an enzyme called leukocyte esterase. Leukocytes are a special type of white blood cell. If leukocyte esterase is present, leukocytes are not far behind.
Urinary Tract Infection
Leukocytes can be found in urine when a urinary tract infection (UTI) is present. The UTI can be in the bladder, the kidneys or the urethra.
Generally, if a UTI is present, the dipstick test will indicate that nitrites are also present in the urine. The patient usually suffers from other symptoms as well. For example, the Merck Manual indicates that these include nausea, vomiting, frequent and painful urination, and fever. Patients with UTIs usually feel pretty miserable.
Kidney Disease
White blood cells in the urine also suggest possible kidney disease. Protein and red blood cells are usually also present in the urine as well. If the kidney disease is very advanced, serum creatinine levels may be elevated. Although the urinalysis of kidney patients and UTI patients are similar, kidney patients don't have the frequent and painful urination that so frequently accompany UTIs. Other than abnormal labs, the kidney patient may feel just fine, unless the disease is very advanced. Even then, the symptoms may be little more than a vague malaise.
Because many different kidney diseases cause elevated white cells, urine protein and red blood cells in urine, it is important not to self-diagnose, but to get to a doctor who can order imaging tests or a biopsy, as needed. Most frequently, these are glomerular diseases such as diabetic nephropathy, IgA nephropathy, hypertensive nephropathy and related disorders.
Obstructions
Obstructions such as tumors and kidney stones can also produce white blood cells in the urine. In these cases, white blood cells are not the first symptom, nor are they necessary to confirm the diagnosis of cancer or stones. Patients with kidney stones experience overwhelming pain, whereas kidney tumors are more subtle. Patients with tumors may be symptomless until the disease is very advanced.
The New York Times Health Guide notes that in addition to white blood cells, urine from patients with stones may also contain crystals or abnormal levels of "chemicals that inhibit or promote stone formation." Likewise, the National Cancer Institute lists many other symptoms of kidney cancer in addition to white blood cells in urine.
False Alarms
The University of Utah warns that white cells in the urine are not necessarily the result of urinary obstructions, tumors or kidney disease. In some instances, the urine specimen becomes contaminated with white blood cells from other parts of the body, such as the vagina or external urethral meatus of either men or women. This contamination is most common in urine specimens from women with vaginal infections.
