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Double-Positive Disease Prognosis — ESENeph MCQ

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ModerateRenal VasculitisDouble-Positive Disease PrognosisESENeph

A 48-year-old man develops rapidly progressive glomerulonephritis with linear IgG staining on IF. He is also ANCA-positive (MPO). What percentage of anti-GBM patients are also ANCA-positive, and what does it mean for prognosis?

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Correct answer: C — Approximately 20-30% of anti-GBM patients are ANCA-positive (double-positive disease); they may have a better renal prognosis than pure anti-GBM disease and are at risk of ANCA vasculitis relapse after anti-GBM remission

Double-positive disease (anti-GBM + ANCA) occurs in approximately 20-30% of anti-GBM patients and 5-10% of ANCA patients. These patients may have a slightly better renal prognosis than pure anti-GBM disease (possibly because the ANCA-associated component is more treatment-responsive). However, they carry the additional risk of ANCA vasculitis relapse after anti-GBM remission (anti-GBM rarely recurs once antibodies clear). Treatment follows the anti-GBM protocol (plasma exchange + Cyclophosphamide + Glucocorticoids). Long-term ANCA monitoring is essential.

Reference: McAdoo et al 2017 – Double-Positive Disease; KDIGO 2024 – AAV; KDIGO 2021 – GN