When you receive urine test results, you might see the abbreviation “LEU.” This stands for leukocytes, which are more commonly known as white blood cells. Their presence in urine can serve as an important indicator of what is happening within the body. While a healthy urinary system typically has very few to no leukocytes, finding them in a urine sample often suggests that the body is actively responding to something.
The Role of Leukocytes
Leukocytes are a component of the body’s immune system. They circulate throughout the body, defending against foreign invaders. Produced in bone marrow, they identify and neutralize pathogens.
Normally, kidneys filter waste from blood, and the urinary tract prevents large numbers of these immune cells from entering. Thus, significant leukocytes are not expected in a healthy individual. Their appearance signals activated defense mechanisms, often in response to an irritant or microorganism.
Causes of Leukocytes in Urine
The presence of leukocytes in urine often indicates infection or inflammation within the urinary tract. Urinary Tract Infections (UTIs) are a frequent cause, occurring when bacteria enter the urethra and ascend into the bladder, triggering an immune response. White blood cells are sent to combat bacteria, leading to their excretion in the urine.
Beyond common UTIs, leukocytes can indicate other conditions affecting the urinary system. Kidney infections (pyelonephritis) involve bacteria traveling from the bladder to the kidneys, causing a more severe inflammatory reaction. Bladder (cystitis) or kidney inflammation can also lead to elevated leukocyte levels without bacterial infection. Kidney diseases or stones, causing irritation or obstruction, may also prompt an immune response resulting in leukocytes in the urine.
Contamination during sample collection, such as from skin cells or vaginal discharge, can introduce leukocytes and lead to a false positive. Less common causes include sexually transmitted infections (STIs), interstitial cystitis, or certain medications.
Interpreting Leukocyte Levels
Leukocyte levels are reported in categories like negative, trace, small, moderate, or large, or as a specific count per high-powered field (HPF). A normal result indicates zero to five white blood cells per HPF. A “trace” amount might not always be clinically significant, especially if no other symptoms are present.
Higher levels, however, suggest an underlying issue. More than five leukocytes per HPF (pyuria) indicates a notable presence. Interpret leukocyte results with other urinalysis parameters, such as nitrites, red blood cells, or protein. Nitrites, a byproduct of bacteria, suggest a bacterial infection when found alongside leukocytes. The overall picture from these combined results helps determine the likely cause of the elevated leukocyte count.
Next Steps After a Positive Result
If your urine test reveals the presence of leukocytes, consult a healthcare professional. Self-diagnosis or self-treatment is not recommended, as the underlying cause must be accurately identified. Your doctor will consider your symptoms, medical history, and urinalysis results to determine the best course of action.
Further evaluation may include a urine culture. This test identifies specific bacteria causing an infection, if present, and helps determine effective antibiotics. For bacterial infections, antibiotics are a common treatment approach. If an infection is ruled out, your doctor may investigate other causes, potentially ordering imaging studies or specialized tests to pinpoint the source of inflammation.