A 32-year-old woman with SLE presents with worsening proteinuria (4.5 g/day), hypertension, and serum creatinine rising to 2.1 mg/dL over 3 months. Renal biopsy shows diffuse proliferative lupus nephritis (ISN/RPS Class IV). What is the current recommended induction immunosuppression per ACR 2021 guidelines?
- A High-dose oral prednisolone alone for 6 months
- B Rituximab monotherapy as first-line induction
- C Cyclophosphamide (NIH protocol) or mycophenolate mofetil plus glucocorticoids ✓
- D Hydroxychloroquine plus azathioprine as induction
Correct answer: C. Cyclophosphamide (NIH protocol) or mycophenolate mofetil plus glucocorticoids
Explanation
For Class III/IV lupus nephritis, ACR 2021 guidelines recommend induction with either mycophenolate mofetil (MMF; 2–3 g/day) or low-dose IV cyclophosphamide (Euro-Lupus protocol) combined with glucocorticoids (pulse methylprednisolone then oral prednisone). The Euro-Lupus regimen uses 6 fortnightly pulses of 500 mg IV cyclophosphamide and has equivalent efficacy with less toxicity than the high-dose NIH protocol. Hydroxychloroquine is an adjunct, not induction therapy. Rituximab is for refractory disease.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
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