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Rituximab Hypogammaglobulinaemia — RACP Adult Medicine MCQ

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ModerateRheumatologyRituximab HypogammaglobulinaemiaRACP Adult Medicine

A 60-year-old woman with severe rheumatoid arthritis on rituximab develops progressive hypogammaglobulinaemia (IgG 2.5 g/L) with recurrent sinopulmonary infections. What is the recommended management?

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Correct answer: E — Increase rituximab dose to improve B-cell depletion

Rituximab-induced secondary hypogammaglobulinaemia is increasingly recognised, particularly with cumulative dosing over years. When IgG falls below ~4 g/L with recurrent infections, immunoglobulin replacement therapy (IVIg 0.4 g/kg monthly or equivalent SCIg) should be commenced. The decision to continue or cease rituximab depends on disease control and availability of alternative effective biologics. IgG levels should be monitored before each rituximab cycle. Some patients recover IgG production months after rituximab cessation; others have persistent hypogammaglobulinaemia requiring ongoing replacement.

Reference: eTG – 2025 – Rheumatology; ASCIA – 2024 – Secondary Immunodeficiency