What is the diagnosis and treatment for a patient presenting with hematuria, purpuric lesions, and ankle pain, potentially indicating an autoimmune condition like Henoch-Schönlein purpura (HSP)?

Henoch-Schönlein Purpura (IgA Vasculitis)

The clinical triad of hematuria, purpuric lesions, and ankle pain is diagnostic of Henoch-Schönlein purpura (HSP), a systemic IgA-mediated vasculitis that requires immediate urinalysis with microscopy to assess for glomerulonephritis and proteinuria, followed by supportive care with close renal monitoring. 1, 2

Diagnostic Approach

Clinical Recognition

The diagnosis can be made clinically when palpable purpura is present plus at least one of the following: renal involvement (hematuria and/or proteinuria), arthralgia/arthritis, or abdominal pain 2. Your patient's presentation with all three classic features—purpuric rash, joint pain, and hematuria—makes HSP the most likely diagnosis 1.

Essential Initial Workup

• Urinalysis with microscopy: Look specifically for proteinuria (>2+ by dipstick), red blood cell casts, and dysmorphic red blood cells, which indicate glomerular involvement 1
• Basic metabolic panel: Include BUN, serum creatinine, and complete blood count with platelets to assess renal function and rule out thrombocytopenia 1
• Blood pressure measurement: Essential as hypertension may indicate more severe renal involvement 1

Critical pitfall: HSP is a nonthrombocytopenic purpura—the presence of thrombocytopenia should prompt consideration of alternative diagnoses like thrombotic microangiopathy 3.

Imaging Considerations

Renal ultrasound is the preferred initial imaging modality to assess kidney size and anatomy, particularly if renal biopsy is being considered for severe nephritis 1. However, imaging is not required for diagnosis when clinical features are classic 1.

Treatment Strategy

Renal Disease Management (Priority for Morbidity/Mortality)

For patients with persistent proteinuria:

• Start ACE inhibitors or ARBs as first-line therapy 2
• If proteinuria exceeds 1 g/day per 1.73 m² after ACE inhibitor/ARB trial and GFR >50 ml/min per 1.73 m², add a 6-month course of corticosteroid therapy 2

For severe crescentic HSP with nephrotic syndrome or deteriorating kidney function:

• Treat with steroids plus cyclophosphamide 2
• Alternative immunosuppressants include azathioprine, cyclosporine, tacrolimus, or mycophenolate mofetil when cyclophosphamide is contraindicated 2

Important caveat: Prophylactic corticosteroids do NOT prevent HSP nephritis and should not be used for this purpose 2. However, steroids are appropriate for severe joint pain or cutaneous symptoms at 1-2 mg/kg daily for two weeks 2.

Pain Management

• First-line: Acetaminophen (paracetamol) is the safest analgesic option 2
• Avoid NSAIDs: Ketorolac (Toradol) and other NSAIDs can cause acute kidney injury, especially problematic given the renal involvement in HSP 2
• For severe pain: Oral prednisone 1-2 mg/kg daily for two weeks may be used 2

Supportive Measures

A low-antigen-content (LAC) diet may improve symptoms when strictly followed for 4-8 weeks and can be considered as adjunctive treatment 2.

Monitoring Protocol

Day 7 urinalysis is critical: A normal urinalysis on day 7 has a 97% negative predictive value for normal renal outcome 4. This should guide the intensity of subsequent monitoring.

Standard monitoring period: All HSP patients require 6 months of monitoring, with intensity based on day 7 urine findings 4:

• Patients with abnormal day 7 urinalysis need more intensive follow-up
• Monitor for persistent hematuria and proteinuria, as these may indicate ongoing disease activity 1

Age consideration: Older patients are at higher risk for renal complications and may require more aggressive monitoring and earlier nephrology referral 4.

When to Refer to Nephrology

Refer for nephrology consultation if:

• Persistent proteinuria >1 g/day per 1.73 m² despite ACE inhibitor/ARB therapy 2
• Deteriorating kidney function 2
• Nephrotic syndrome develops 2
• Crescentic glomerulonephritis on biopsy 2

Adult patients: The treatment approach should mirror that used in children, though adults tend to have worse prognosis and higher rates of progressive renal disease 2, 5.

Prognosis Considerations

While HSP is typically self-limiting, renal involvement is the primary determinant of long-term morbidity 3, 6. The 9% rate of subsequent renal referral and 1% rate requiring biopsy and immunosuppression underscores the importance of systematic monitoring 4. CNS complications occur in approximately one-third of patients (usually mild headaches and behavioral changes), but severe neurologic manifestations are rare and more common in adults with severe disease 6.