What is the evaluation and treatment approach for a child with trace blood in their urine, also known as hematuria?

Evaluation and Management of Trace Blood in Pediatric Urine

For isolated microscopic hematuria (trace blood) in children without proteinuria, hypertension, or other concerning features, clinical follow-up without immediate imaging is the recommended approach, as these patients are unlikely to have clinically significant renal disease. 1

Initial Confirmation and Assessment

Confirm true hematuria by verifying ≥5 red blood cells per high-power field on microscopic examination in 2-3 consecutive urine specimens, as dipstick positivity alone is insufficient for diagnosis. 1 Rule out factitious causes such as food substances (beets, blackberries) or medications (rifampin, phenazopyridine) that color urine without actual red blood cells. 2, 1

Critical History Elements

Obtain specific information about: 2, 1

• Family history: Stone disease, hearing loss, familial renal disease (Alport syndrome), or thin basement membrane nephropathy
• Recent illnesses: Streptococcal pharyngitis (postinfectious glomerulonephritis), viral infections
• Trauma history: Including occult trauma or foreign body insertion
• Urinary symptoms: Dysuria, frequency, flank pain (suggests stones or infection)
• Systemic symptoms: Joint pains, rash, bloody diarrhea (suggests vasculitis or systemic disease)
• Medications and supplements: That could cause hematuria

Essential Physical Examination Findings

Assess for: 2, 1

• Blood pressure: Hypertension suggests glomerular disease
• Growth parameters: Height and weight to evaluate for chronic kidney disease
• Edema: Periorbital or peripheral edema suggests glomerulonephritis
• Rashes or arthritis: May indicate systemic disease (Henoch-Schönlein purpura, lupus)
• Abdominal masses: Palpable kidney or bladder masses

Laboratory Evaluation

Mandatory Testing

Complete urinalysis with microscopic examination is the only universally required test. 3 Specifically evaluate for: 2, 1

• Proteinuria: >2+ by dipstick suggests glomerular disease and requires extensive evaluation
• Red blood cell morphology: Dysmorphic RBCs or red cell casts indicate glomerular source
• White blood cells and bacteria: Suggests urinary tract infection
• Crystals: May indicate stone disease

Additional First-Line Tests

• Spot urine calcium-to-creatinine ratio: Hypercalciuria is a common cause of microscopic hematuria in children 2, 1
• Urine culture: To exclude urinary tract infection 2, 1

When to Obtain Blood Work

For isolated microscopic hematuria without proteinuria, red cell casts, or hypertension, blood tests are typically not needed initially. 1 However, if concern for chronic kidney disease exists, obtain: 2

• Serum creatinine and blood urea nitrogen
• Complete blood count with platelets

Imaging Decisions

Isolated Microscopic Hematuria (No Proteinuria, Normal BP)

Imaging is not appropriate for initial evaluation. 1 Most children with isolated microscopic hematuria have benign conditions and do not require imaging. 1 CT imaging is specifically not appropriate in this scenario. 1

When Imaging IS Indicated

Renal ultrasound is the appropriate first-line imaging modality when: 2, 4, 5

• Hematuria persists beyond 6-12 months of follow-up
• Proteinuria is present (>2+ by dipstick)
• Hypertension is documented
• Abdominal mass is palpable
• Family history suggests structural abnormalities
• Concern for anatomic abnormalities or stones

Ultrasound displays kidney anatomy, size, and position effectively without radiation exposure. 2

Common Etiologies and Their Implications

Benign Causes (Most Common)

• Thin basement membrane nephropathy: Most common cause of persistent isolated microscopic hematuria; excellent prognosis 1, 6
• Idiopathic hypercalciuria: Common and treatable cause 1
• Benign familial hematuria: Consider family screening 1

Potentially Progressive Causes

• IgA nephropathy (Berger disease): Cannot be distinguished from thin basement membrane nephropathy without renal biopsy; may be progressive 1, 6
• Alport syndrome: Suspect with family history of hearing loss or renal disease 2

Follow-Up Strategy for Isolated Microscopic Hematuria

For persistent isolated microscopic hematuria without proteinuria or hypertension: 1

• Periodic urinalysis (every 3-6 months) to monitor for development of proteinuria
• Blood pressure monitoring at each visit
• Consider renal ultrasound if hematuria persists beyond 6-12 months, though diagnostic yield is low
• Family screening may identify benign familial hematuria

Indications for Nephrology Referral

Refer to pediatric nephrology when: 1, 3

• Proteinuria is present (>2+ by dipstick or protein-to-creatinine ratio >0.2)
• Dysmorphic RBCs or red cell casts are identified (strongly suggests glomerular disease)
• Hypertension is documented
• Elevated serum creatinine or declining kidney function
• Family history of progressive renal disease or Alport syndrome
• Persistent hematuria with unclear etiology after initial evaluation

Critical Pitfalls to Avoid

Do not assume all "blood" in urine is true hematuria. Always confirm with microscopic examination showing ≥5 RBCs/HPF, as dipstick can be falsely positive from myoglobin, hemoglobin, or other substances. 1

Do not order extensive imaging for isolated microscopic hematuria. Children have much lower risk of significant urologic disease compared to adults, and most cases are benign. 1, 7

Do not miss proteinuria. Proteinuria is often more important diagnostically and prognostically than hematuria alone and mandates more aggressive evaluation. 2, 8

Do not delay evaluation if gross hematuria or concerning features are present. While isolated microscopic hematuria can be followed conservatively, macroscopic hematuria, proteinuria, hypertension, or systemic symptoms require prompt evaluation. 2