From the Guidelines
The presence of leukocytes in a child's urinalysis is a significant indicator of urinary tract infection (UTI) and warrants further evaluation with a urine culture to confirm infection, as supported by the most recent study 1. When interpreting the results of a urinalysis, it is essential to consider the sensitivity and specificity of the tests used. The leukocyte esterase test, which detects the presence of white blood cells in the urine, has a higher sensitivity (84%) compared to the nitrite test (34.2% to 44.6%) 1.
Key Points to Consider
- The presence of leukocytes in the urine can be detected indirectly using the leukocyte esterase test, which has a higher sensitivity but lower specificity compared to the nitrite test 1.
- A meta-analysis of diagnostic tests for UTI in children found that the combination of leukocyte esterase and nitrite tests had a sensitivity of 88% and a specificity of 79% 1.
- The presence of leukocytes in the urine can indicate inflammation in the urinary tract, which may be caused by a UTI, and further evaluation with a urine culture is recommended to confirm infection.
- Empiric antibiotic therapy may be initiated while awaiting culture results, especially if the child is symptomatic, with common first-line antibiotics including trimethoprim-sulfamethoxazole or cephalexin 1.
Recommendations
- If a child's UA shows leukocytes, further evaluation with a urine culture is recommended to confirm infection.
- While awaiting culture results, empiric antibiotic therapy may be initiated, especially if the child is symptomatic.
- Additional testing, such as renal ultrasound, may be indicated, particularly for boys, children under 3 years, or those with recurrent infections to identify anatomical abnormalities.
- It is essential to note that sterile pyuria (leukocytes without bacteria) can occur with partial antibiotic treatment, viral infections, or inflammatory conditions, and therefore, a positive urinalysis result should prompt a urine culture obtained by catheterization or suprapubic aspiration 1.
From the Research
Significance of Leukocytes in Urinalysis
The presence of leukocytes (white blood cells) in a child's urinalysis is a significant indicator of a potential urinary tract infection (UTI) 2, 3, 4, 5, 6.
- Leukocytes are a type of white blood cell that helps fight infection and inflammation in the body.
- The presence of leukocytes in the urine, also known as pyuria, can indicate that the body is responding to a UTI 3.
- A urinalysis that shows pyuria, along with other symptoms such as fever, dysuria, and abdominal pain, can help diagnose a UTI in children 2, 4, 6.
Diagnostic Value of Leukocytes
The diagnostic value of leukocytes in urinalysis is significant, as it can help identify children who are at risk of UTI 4, 5.
- A study found that the presence of leukocytes, along with other symptoms and signs, can help guide antibiotic treatment in children with UTI 4.
- Another study found that unspun urine leukocyte count and gram stain of cytocentrifuged urine used in parallel was the best approach to predict UTI in young children 5.
- The presence of leukocytes in the urine can also help distinguish between a UTI and other conditions that may cause similar symptoms 3, 6.
Clinical Implications
The presence of leukocytes in a child's urinalysis has significant clinical implications 2, 3, 4, 5, 6.
- It can help guide antibiotic treatment and ensure prompt treatment of UTIs, which can reduce the risk of renal scarring and other complications 2, 3.
- It can also help identify children who are at risk of recurrent UTIs and may benefit from further evaluation and treatment 3, 6.
- The presence of leukocytes in the urine can also help monitor the effectiveness of treatment and ensure that the infection is fully cleared 2, 4.