Suspected lupus nephritis — SCE Rheumatology MCQ

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ModerateConnective tissue diseasesSuspected lupus nephritisSCE Rheumatology

A 22-year-old woman with systemic lupus erythematosus develops frothy urine and ankle oedema. Her blood pressure is 156/96 mmHg. Urine protein:creatinine ratio is 310 mg/mmol, eGFR is 62 mL/min/1.73 m², and serum C3 is low. Which investigation is most appropriate to establish the diagnosis and guide immunosuppressive treatment?

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Correct answer: C — Percutaneous kidney biopsy

The correct answer is C: percutaneous kidney biopsy. She has probable active lupus nephritis, with substantial proteinuria, oedema, hypertension, impaired renal function and hypocomplementaemia. Kidney biopsy is needed promptly to confirm renal involvement, identify the histological class, and define activity and chronicity indices; these findings determine the appropriate immunosuppressive regimen and inform prognosis. Urine microscopy and anti-double-stranded DNA titre may support an assessment of disease activity but cannot determine renal histology. A 24-hour protein collection adds little when proteinuria has already been quantified by protein:creatinine ratio. Ultrasound may assess renal anatomy or exclude obstruction but does not establish or classify lupus nephritis.

Reference: Fanouriakis A, et al. EULAR recommendations for the management of systemic lupus erythematosus with kidney involvement: 2025 update. Ann Rheum Dis. 2026;85:75-90. https://pubmed.ncbi.nlm.nih.gov/41107121/