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MGUS Progression to Myeloma — RACP Adult Medicine MCQ

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ModerateHaematologyMGUS Progression to MyelomaRACP Adult Medicine

A 68-year-old man with known MGUS (IgG kappa 15 g/L, diagnosed 5 years ago) presents with a rising paraprotein (now 25 g/L), new anaemia (Hb 95 g/L), and bone pain. His calcium is 2.85 mmol/L and creatinine is 170 µmol/L. Bone marrow shows 25% plasma cells. What has occurred?

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Correct answer: B — Progression to multiple myeloma

This patient has progressed from MGUS to symptomatic multiple myeloma, meeting CRAB criteria: Calcium elevation, Renal impairment, Anaemia, and Bone lesions (pain). Additionally, bone marrow plasma cells ≥10% with end-organ damage confirms the diagnosis. MGUS progresses to myeloma at ~1% per year. Risk factors for progression include paraprotein >15 g/L, non-IgG isotype, and abnormal free light chain ratio. This patient requires treatment initiation.

Reference: eTG – 2025 – Haematology; IMWG – 2014 – Diagnostic Criteria for Multiple Myeloma