What can cause the presence of white blood cells (WBCs) in urine?

The presence of white blood cells (WBCs) in urine is primarily indicative of an underlying pathology, most commonly a urinary tract infection (UTI) or inflammation within the urinary system. When there is a UTI, the body mobilizes WBCs to the site of infection as part of the immune response. This influx of white blood cells is a natural defense mechanism aimed at combating pathogens in the urinary tract. Consequently, a significant number of WBCs in urine can be attributed to conditions such as cystitis (bladder infection) or pyelonephritis (kidney infection), both of which are characterized by inflammation in response to infection.

While other options may present conditions that affect urine composition or kidney health, they do not directly correlate with the presence of WBCs in urine in the same straightforward manner as a urinary tract infection does. Excessive hydration typically leads to diluted urine, which may reduce the concentration of WBCs but does not introduce them. Kidney stones may cause irritation or trauma to urinary tissues, potentially leading to some inflammatory response, but they are not the primary cause of WBCs in urine compared to infections. A high protein diet impacts urine protein levels and can result in metabolic changes but does not directly lead