What are the causes of hematuria in children, and what investigations and drug treatments are recommended for management?

Hematuria in Children: Causes, Investigations, and Management

For isolated microscopic hematuria without proteinuria or dysmorphic red blood cells in children, no imaging is indicated and clinical observation is appropriate, as these patients are unlikely to have clinically significant renal disease 1.

Causes of Hematuria in Children

The differential diagnosis varies by clinical presentation:

Glomerular Causes

• Postinfectious glomerulonephritis (most common glomerulonephritis in children) 2
• IgA nephropathy (Berger disease) - requires renal biopsy for diagnosis 1
• Alport syndrome - suspect with family history of hearing loss or renal disease 1
• Thin basement membrane nephropathy - most common cause of persistent microscopic hematuria, usually benign 1, 2
• Henoch-Schönlein purpura
• Systemic lupus erythematosus

Non-Glomerular Causes

• Urinary tract infection - most common overall cause 2, 3
• Hypercalciuria - found in 33.7% of children with idiopathic hematuria 4
• Hyperuricosuria - present in 35.8% of cases 4
• Urolithiasis
• Trauma (blunt or penetrating)
• Sickle cell disease
• Coagulopathy

Metabolic Abnormalities

94% of children with idiopathic hematuria have urinary metabolic abnormalities, most commonly hypocitraturia (60.7%) and hypomagnesuria (58.2%) 4.

Algorithmic Approach to Investigation

Step 1: Clinical History - Key Red Flags

Look specifically for:

• Tea-colored urine (suggests glomerular source) 1
• Recent streptococcal infection
• Hearing loss or family history of renal disease (Alport syndrome)
• Rash, arthritis, bloody diarrhea (systemic disease)
• Trauma history
• Strenuous exercise
• Menstruation in adolescent females
• Family history of sickle cell disease, hemophilia, or nephrolithiasis 1

Step 2: Urinalysis with Microscopy

Critical findings that determine next steps:

• Proteinuria >2+ by dipstick + dysmorphic RBCs + RBC casts = glomerular disease requiring nephrology referral 1
• White cells + organisms = UTI, treat accordingly
• Isolated microscopic hematuria (≥5 RBCs/HPF in 2-3 consecutive specimens) without proteinuria = low risk 1

Step 3: Initial Laboratory Testing

For all patients with persistent hematuria:

• Spot urine calcium-to-creatinine ratio (evaluate hypercalciuria) 1
• Urine culture 1

When chronic kidney disease suspected:

• Blood urea nitrogen
• Serum creatinine
• Complete blood count with platelets 1

For glomerular disease suspected:

• Complement levels (C3, C4)
• Antistreptolysin O titer
• Anti-DNase B
• ANA, anti-dsDNA (if lupus suspected)
• Audiogram and slit lamp examination if Alport syndrome suspected 1

Step 4: 24-Hour Urine Collection for Metabolic Evaluation

Strongly recommended for isolated idiopathic hematuria 4:

• Calcium, citrate, oxalate, phosphate
• Uric acid, cystine, magnesium
• This identifies treatable metabolic causes in 94% of cases

Step 5: Imaging - Clinical Scenario-Based

Isolated microscopic hematuria WITHOUT proteinuria:

• No imaging indicated 1
• Exception: Consider renal ultrasound if hypercalciuria or hyperuricosuria documented to evaluate for stones 1

Hematuria WITH proteinuria or dysmorphic RBCs:

• Renal ultrasound to assess kidney size, position, and structural abnormalities before potential biopsy 1

Painful hematuria:

• Renal ultrasound first-line to evaluate for stones, obstruction

Post-traumatic macroscopic hematuria:

• CT urography to identify extent of renal/urinary tract injury 1

Post-traumatic microscopic hematuria:

• Clinical observation typically sufficient

Important caveat: CT is NOT appropriate for isolated nonpainful, nontraumatic hematuria 1

Drug Treatment Recommendations

For Hypercalciuria-Associated Hematuria

Potassium citrate supplementation is highly recommended to prevent future stone formation and treat hematuria 4. This addresses the most common metabolic abnormality (hypocitraturia in 60.7% of cases).

For Urinary Tract Infection

Appropriate antibiotics based on culture and sensitivity

For Glomerulonephritis

Treatment depends on specific diagnosis:

• Postinfectious glomerulonephritis: supportive care, manage hypertension and edema
• IgA nephropathy: ACE inhibitors/ARBs if proteinuria present
• Lupus nephritis: immunosuppression per nephrology
• Alport syndrome: ACE inhibitors/ARBs to slow progression

For Idiopathic Hematuria with Metabolic Abnormalities

Potassium citrate for hypocitraturia and hypercalciuria 4

Critical Clinical Pitfalls

1. Do not over-image isolated microscopic hematuria - 87% of children in one study had renal ultrasound with no clinically significant findings 1

2. Screen family members' urine for persistent unexplained microhematuria to identify benign familial hematuria 1

3. Proteinuria changes everything - presence of proteinuria with hematuria mandates nephrology evaluation for glomerular disease 1, 5

4. Most isolated microscopic hematuria is benign - 88.5% have microscopic hematuria with benign course, requiring only clinical observation 4, 2

5. Measure urinary biochemistry in all children with isolated hematuria, as 94% have treatable metabolic abnormalities 4

6. Refer to pediatric nephrology when:

   • Hematuria persists >2 weeks after glomerulonephritis onset
   • Renal biopsy needed
   • Persistent microscopic hematuria with unclear etiology 5