Leukocytes are white blood cells that defend the body against foreign invaders like bacteria and viruses. While these cells circulate throughout the body, their presence in urine is typically unexpected in significant amounts. Urinalysis, a common diagnostic procedure, helps determine the presence of various substances in urine, including leukocytes, providing early indications of potential health concerns.
Understanding Leukocytes and Urine Tests
A urinalysis examines a urine sample to detect substances, including leukocytes. When a urinalysis report indicates a “trace” amount of leukocytes, it signifies a small, detectable quantity. This finding is often reported as “trace,” “+/-“, or “1+” on a dipstick test. An enzyme called leukocyte esterase, released by white blood cells, is detected by dipstick tests. While any leukocytes in urine can signal a bodily response, the exact meaning of a “trace” amount requires further consideration.
Interpreting Trace Leukocytes
Detecting a “trace” of leukocytes in urine does not automatically indicate a serious medical problem; it can sometimes be a normal or benign finding. For instance, contamination of the urine sample during collection, often from genital skin or discharge, can lead to a false positive result. Mild dehydration or temporary inflammation not related to a severe condition might also cause a small increase in leukocytes.
Even a trace amount, however, can be an early signal of an underlying issue. Factors influencing the interpretation include the presence of other symptoms, such as painful urination or fever, and other findings from the urinalysis. For example, if a trace of leukocytes is found alongside nitrites, which are waste products of certain bacteria, it strongly suggests a urinary tract infection. Therefore, while a trace can sometimes be benign, it often warrants further investigation to determine its clinical significance.
Conditions Associated with Leukocytes in Urine
Numerous medical conditions can lead to the presence of leukocytes in urine, even in trace amounts. Urinary tract infections (UTIs) are among the most common causes, where bacteria entering the urinary tract trigger an immune response, sending white blood cells to the infection site. Kidney infections can also cause an increase in leukocytes, often spreading from the lower urinary tract. Kidney stones, mineral and salt accumulations, can irritate the urinary tract or cause blockages, leading to inflammation and leukocytes.
Inflammation of the bladder (cystitis) or urethra (urethritis), even without a bacterial infection, can result in leukocytes in urine, including conditions like interstitial cystitis. Sexually transmitted infections (STIs) such as chlamydia, gonorrhea, and trichomoniasis can also cause leukocytes to appear in urine. Additionally, certain kidney diseases, some cancers, and particular medications can contribute to elevated leukocyte levels in urine.
Next Steps and Diagnosis
If a trace of leukocytes is detected in a urine test, consulting a healthcare provider is important for proper interpretation and further evaluation. The provider will consider accompanying symptoms, such as frequent urination, burning sensation during urination, or lower back pain, as these significantly influence the course of action. Common follow-up diagnostic steps include a repeat urinalysis, especially if contamination is suspected, often using a clean-catch method to ensure sample purity.
A urine culture may be ordered to identify specific bacteria or other microorganisms causing an infection. Blood tests can help identify systemic infections or other health issues. In some cases, imaging studies like ultrasound, CT scans, or MRI may be used to look for structural problems in the urinary tract, such as kidney stones or obstructions. A trace finding of leukocytes is often a starting point for investigation, not a definitive diagnosis, and many underlying causes are treatable.