What urine tests can rule out cancer in a child?

Urine Tests for Cancer Detection in Children

No single urine test can reliably rule out cancer in children, and routine urinalysis is not recommended as a cancer screening tool in asymptomatic pediatric patients. However, specific urine tests may be indicated based on clinical presentation, symptoms, or known cancer predisposition syndromes.

Context-Specific Urine Testing Recommendations

For Children with Suspected Urinary Tract Malignancies

Urinalysis for hematuria is the primary urine-based screening test when bladder cancer is suspected, though it has significant limitations:

• Microscopic hematuria (≥5 red blood cells per high power field) warrants further evaluation with imaging (renal and bladder ultrasound) rather than relying on urine tests alone to exclude malignancy 1
• Annual urinalysis for hematuria is recommended beginning at age 10 years specifically for children with Costello syndrome due to elevated bladder cancer risk 1
• Urine cytology has poor sensitivity, particularly for low-grade tumors, making it unreliable for ruling out bladder cancer 2

For Children with Known Cancer or Cancer Predisposition

Urinalysis and urine culture serve different purposes in pediatric oncology patients:

• In children with fever and neutropenia during cancer treatment, obtain urinalysis and urine culture before starting antibiotics when a clean-catch specimen can be collected without delaying treatment 1
• Pyuria is present in only 4% of urinary tract infections during neutropenia (compared to 68% in non-neutropenic patients), so absence of pyuria does not rule out infection 1
• For cancer survivors previously treated with ifosfamide or total body irradiation, annual urinalysis screening (checking for proteinuria ≥1+, glucosuria, or ≥5 RBCs/HPF) detects late genitourinary complications, with abnormal findings in 5.3% of screenings 3

Specific Biomarker Testing Limitations

Avoid urinary VMA/HVA testing for neuroblastoma screening in children with Costello syndrome due to high false-positive rates 1

Critical Pitfalls to Avoid

• Do not rely on nitrite testing alone to exclude urinary tract pathology in children, as it has only 53% sensitivity despite 98% specificity 4, 5
• Do not use urinalysis as a standalone cancer screening tool in asymptomatic children without specific risk factors, as there is inadequate evidence supporting this approach 1
• Do not delay imaging (ultrasound or advanced imaging) when clinical suspicion for malignancy exists, as urine tests cannot definitively exclude cancer 6

Evidence-Based Algorithm

For a child with concerning symptoms (hematuria, abdominal mass, unexplained weight loss):

1. Obtain urinalysis to document hematuria and assess for infection 1, 5
2. Proceed immediately to imaging (renal and bladder ultrasound) rather than waiting for additional urine test results 6
3. Add urine culture if infection is suspected, recognizing that 10-50% of culture-proven UTIs have false-negative urinalysis 5
4. Consider specialized testing only in specific genetic syndromes (annual urinalysis for hematuria in Costello syndrome patients ≥10 years) 1

The strength of evidence for using urine tests to rule out cancer in children is weak, with most guidelines emphasizing that clinical evaluation and imaging are superior to urine-based screening for cancer detection 1, 2.