What is the recommended treatment for a child or young adult with Henoch-Schönlein Purpura (HSP), presenting with purpura, joint pain, and gastrointestinal issues, and a history of recent upper respiratory tract infections, with potential kidney involvement and impaired renal function?

Management of Henoch-Schönlein Purpura with Renal Involvement

For a child or young adult with HSP presenting with purpura, joint pain, GI symptoms, and impaired renal function, initiate supportive care with acetaminophen for pain control, start ACE inhibitor or ARB therapy for persistent proteinuria, and escalate to corticosteroids with or without cyclophosphamide based on the severity of renal involvement. 1, 2

Initial Assessment and Monitoring

Perform immediate urinalysis with microscopy to assess for red blood cell casts and dysmorphic RBCs, which indicate glomerular involvement. 1, 2 Quantify proteinuria using spot urine protein-to-creatinine ratio or 24-hour urine collection. 1, 2

• Obtain basic metabolic panel including BUN and serum creatinine to assess renal function 1, 2
• Measure blood pressure, as hypertension indicates more severe renal involvement 1, 2
• Complete blood count to rule out thrombocytopenia 1
• Consider renal ultrasound if renal biopsy is being considered for severe nephritis 1

Perform renal biopsy if: decreased renal function at presentation, severe nephrotic syndrome (proteinuria >3.5 g/day), nephritic syndrome, or deteriorating kidney function. 2

Pain Management

Use acetaminophen (paracetamol) as first-line analgesic for joint pain and cutaneous symptoms. 1

• Avoid NSAIDs (ketorolac/Toradol) in patients with renal involvement, as they can cause acute kidney injury, especially with pre-existing renal impairment 1, 2
• Oral prednisone at 1-2 mg/kg daily for two weeks may be used for acute pain control if acetaminophen is insufficient 1, 3

Treatment Algorithm Based on Renal Severity

Mild Renal Involvement (Proteinuria 0.5-1 g/day per 1.73 m²)

Start ACE inhibitor or ARB therapy targeting proteinuria reduction to <1 g/day per 1.73 m². 1, 2 Do not attempt complete normalization to <0.5 g/day, as this increases side effects without proven benefit. 1

• Maintain blood pressure below the 90th percentile for age and gender 4
• Continue ACE-I/ARB for 3-6 months before considering escalation 4

Moderate Renal Involvement (Proteinuria >1 g/day per 1.73 m²)

If proteinuria persists >1 g/day per 1.73 m² after 3-6 months of optimized ACE-I/ARB therapy and GFR remains >50 ml/min per 1.73 m², add a 6-month course of corticosteroid therapy. 1, 2

• Use either IV methylprednisolone (1 gram daily for 3 consecutive days at months 1,3, and 5) or oral prednisone/prednisolone (starting 0.8-1 mg/kg/day for 2 months, then taper by 0.2 mg/kg/day monthly for 4 months) 4
• This approach is supported by moderate quality evidence showing corticosteroids reduce persistent renal disease when used for established proteinuria 3

Severe Renal Involvement (Crescentic HSP)

For crescentic HSP with nephrotic syndrome and/or deteriorating kidney function (defined as >50% of glomeruli with crescents on biopsy), treat with high-dose intravenous methylprednisolone plus cyclophosphamide. 1, 2

• This represents the most aggressive intervention reserved for rapidly progressive glomerulonephritis 5, 6
• Alternative immunosuppressants (azathioprine, cyclosporine, tacrolimus, mycophenolate mofetil) may be considered, though cyclophosphamide is preferred for crescentic disease 1

Critical Pitfalls to Avoid

Do NOT use corticosteroids prophylactically at HSP onset to prevent nephritis. Moderate quality evidence (Level 1B) demonstrates no benefit in preventing nephritis or reducing risk of severe persistent nephritis. 1, 2, 7

Do NOT start corticosteroids too early for mild proteinuria without an adequate 3-6 month trial of ACE inhibitor/ARB therapy, as this increases side effects without proven benefit. 1

Do NOT delay renal biopsy if there is deteriorating kidney function, as this may represent crescentic disease requiring aggressive immunosuppression. 2, 6

Special Considerations for Adults

Treat adults with HSP nephritis using the same approach as children, though adults have worse prognosis and higher risk of progression to end-stage renal disease (1-5% of patients). 1, 3

Follow-Up Protocol

Monitor all HSP patients for at least 6 months with regular urinalysis for proteinuria and hematuria, plus blood pressure measurements. 8, 9

• A normal urinalysis on day 7 has a 97% negative predictive value for normal renal outcome 9
• Older patients are at higher risk of requiring renal referral 9
• Women with childhood HSP history require close monitoring during pregnancy for proteinuria and hypertension 8

Gastrointestinal Management

For severe abdominal pain, oral prednisone at 1-2 mg/kg daily for two weeks reduces mean time to resolution. 3 Consider low-antigen-content (LAC) diet for 4-8 weeks as supportive treatment when strictly followed. 1