A 35-year-old woman with a 3-week history of fever, arthralgia, and palpable purpura on the lower extremities and buttocks is found to have elevated creatinine and hematuria. Skin biopsy shows IgA-dominant immune complex deposition. What is the first-line treatment?

Explanation

## IgA Vasculitis (Henoch–Schönlein Purpura) — First-Line Treatment with Renal Involvement ### Clinical Diagnosis This patient has IgA vasculitis (IgAV, formerly HSP) with: - Palpable purpura (lower extremities and buttocks — classic distribution) - Systemic symptoms (fever, arthralgia) - **Significant renal involvement** (elevated creatinine + hematuria) - IgA-dominant immune complex deposition on skin biopsy ### First-Line Treatment: Prednisolone **Key Point:** While mild IgA vasculitis without renal involvement may be managed conservatively, this patient has **elevated creatinine and hematuria**, indicating moderate-to-severe renal involvement. Per Harrison's Principles of Internal Medicine (21e, Ch. 319) and EULAR/PRES guidelines, systemic corticosteroids (prednisolone 0.5–1 mg/kg/day) are the first-line treatment for IgAV with significant renal involvement to reduce inflammation and prevent progression to chronic kidney disease. ### Management Algorithm | Disease Severity | First-Line Treatment | |-----------------|---------------------| | Mild (purpura, arthralgia only, no renal) | Supportive care + NSAIDs | | **Moderate-severe renal involvement (↑Cr, hematuria, proteinuria >1 g/day)** | **Prednisolone 0.5–1 mg/kg/day** | | RPGN with crescents / progressive renal failure | Cyclophosphamide + corticosteroids | ### Why Prednisolone is Correct Here **High-Yield:** The critical distinguishing feature in this stem is **elevated creatinine** — this is not mild or uncomplicated IgAV. Elevated creatinine signals impaired glomerular filtration, placing this patient in the moderate-to-severe renal involvement category. Corticosteroids are indicated to: 1. Suppress IgA immune complex–mediated glomerular inflammation 2. Reduce proteinuria and hematuria 3. Prevent progression to chronic renal failure ### Why Not Other Options? - **Supportive care and NSAIDs (D):** Appropriate only for mild IgAV without significant renal involvement. NSAIDs may actually worsen renal function in a patient with elevated creatinine and are contraindicated in this setting. - **Cyclophosphamide (C):** Reserved for rapidly progressive glomerulonephritis (RPGN) with crescentic changes or corticosteroid-refractory disease; not first-line. - **Plasmapheresis (A):** No proven benefit in IgA vasculitis; not standard therapy per current guidelines. **Clinical Pearl:** NSAIDs are relatively contraindicated when creatinine is already elevated, as they reduce renal prostaglandin synthesis and can precipitate acute kidney injury — making option D not only suboptimal but potentially harmful in this clinical scenario. [cite: Harrison 21e Ch. 319; Robbins & Cotran Pathologic Basis of Disease 10e Ch. 11; EULAR/PRES guidelines for IgA vasculitis]