How should I evaluate and manage a patient with suspected Henoch‑Schönlein purpura presenting with palpable purpura on the lower extremities, arthralgia, abdominal pain, and possible hematuria?

Evaluation and Management of Henoch-Schönlein Purpura (HSP)

Begin immediate urinalysis with microscopy at presentation and every follow-up visit to detect hematuria, proteinuria, red blood cell casts, and dysmorphic red blood cells—this is the single most critical step to prevent missing renal involvement that determines long-term prognosis. 1

Initial Diagnostic Evaluation

The diagnosis is clinical when palpable purpura is present plus at least one of: renal involvement (hematuria/proteinuria), arthralgia/arthritis, or abdominal pain 1, 2. Your patient meets criteria with purpura, arthralgia, abdominal pain, and possible hematuria.

Essential Laboratory Testing

• Urinalysis with microscopy: Look specifically for proteinuria, red blood cell casts, and dysmorphic red blood cells indicating glomerular involvement 1
• Urine protein-to-creatinine ratio or 24-hour urine protein: Quantify proteinuria to guide treatment decisions 1
• Basic metabolic panel: Assess BUN and serum creatinine for renal function 1
• Complete blood count with platelets: Rule out thrombocytopenia (platelets should be normal in HSP) 1
• Blood pressure measurement: Hypertension indicates more severe renal involvement 1

Additional Workup for Adults

In adult patients specifically, screen for secondary causes and malignancy with age- and sex-appropriate screening tests 3. Adults have worse prognosis than children and higher risk of progression to end-stage renal disease 1.

Management Strategy

Supportive Care for Mild Disease

Most HSP cases are self-limited with average duration of 4 weeks 2. For patients without severe manifestations:

• Acetaminophen (paracetamol) is the first-line analgesic for joint and skin pain 1
• Avoid NSAIDs like ketorolac (Toradol): These can cause acute kidney injury, especially with pre-existing renal impairment 1
• Dietary sodium restriction to <2.0 g/day 3

Treatment of Severe Abdominal Pain

Oral prednisone 1-2 mg/kg daily for two weeks may be used for severe gastrointestinal pain and hemorrhage 1, 4. This reduces mean time to resolution of abdominal pain 4.

Renal Disease Management Algorithm

This is where treatment decisions critically impact long-term morbidity and mortality:

Step 1: Persistent Proteinuria Without Severe Features

• Start ACE inhibitor or ARB for persistent proteinuria, even without hypertension 1, 2
• Target proteinuria to <1 g/day/1.73 m² rather than complete normalization 1
• Continue for at least 3 months before escalating therapy 1

Step 2: Persistent Proteinuria >1 g/day/1.73 m² After 3 Months

If proteinuria remains >1 g/day/1.73 m² despite ACE inhibitor/ARB therapy AND eGFR >50 ml/min/1.73 m²:

• Consider 6-month course of oral corticosteroids 1, 2
• This is suggested but not definitively proven to prevent progression 1

Step 3: Severe Renal Involvement

For crescentic HSP with nephrotic syndrome (proteinuria >3.5 g/day) and/or deteriorating kidney function:

• High-dose IV methylprednisolone PLUS cyclophosphamide following the same protocol as crescentic IgA nephropathy 1, 2
• Alternative immunosuppressants include azathioprine, cyclosporine, tacrolimus, or mycophenolate mofetil 1

Critical Management Pitfalls to Avoid

Do NOT use prophylactic corticosteroids at HSP onset to prevent nephritis—moderate quality evidence (Grade 1B) shows no benefit in preventing nephritis or reducing risk of severe persistent nephritis 3, 1. This is a common error that exposes patients to steroid toxicity without benefit.

Do NOT start corticosteroids too early for mild proteinuria without adequate trial (at least 3 months) of ACE inhibitor/ARB therapy 1. Early steroid treatment does not reduce incidence or severity of nephropathy 2.

Do NOT attempt to normalize proteinuria to <0.5 g/day/1.73 m²—this increases medication side effects without proven benefit 1.

Monitoring Protocol

• Urinalysis at every clinical visit to detect renal relapse early 1
• Monitor blood pressure at each visit 1
• Follow proteinuria and renal function for at least 6 months, as most nephritis develops within 3 months of presentation 3
• Adults require longer monitoring due to worse prognosis 1

Imaging Considerations

Renal ultrasound is the preferred initial imaging to assess kidney size and anatomy, particularly if renal biopsy is being considered for severe nephritis 1. Biopsy is not routinely needed for diagnosis but may be indicated for severe or atypical renal involvement.

Prognosis

Long-term prognosis depends entirely on severity of renal involvement 2, 4. End-stage renal disease occurs in 1-5% of patients 4. Adults have significantly worse outcomes than children 1, 5.