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This algorithm addresses risk stratification and follow-up for monoclonal gammopathy of undetermined significance (MGUS), defined here as an M-protein below 3 g/dL with fewer than 10% clonal plasma cells and no end-organ damage. CRAB features must be excluded before the diagnosis is made. Risk is assigned using three factors: M-protein of 1.5 g/dL or higher, a non-IgG isotype, and an abnormal serum free light-chain ratio.
Low-risk MGUS is monitored by repeating the SPEP at 6 months and then every 2 to 3 years, without bone marrow examination or imaging. Intermediate-risk or high-risk MGUS warrants a bone marrow evaluation and whole-body imaging, followed by annual follow-up. IgM MGUS is handled as a separate branch because of its distinct biology: surveillance is directed toward progression to Waldenström macroglobulinemia or lymphoma rather than myeloma. The chart is a simplified board-review scaffold, and no specific trials are linked to it.
Background reading: Multiple myeloma, MGUS, and smoldering myeloma board review notes.
Monoclonal gammopathy of undetermined significance: work-up and follow-up by risk. Starting point: MGUS M-protein < 3 g/dL < 10% plasma cells. Full background: Multiple myeloma, MGUS, and smoldering myeloma notes.
Simplified board-prep scaffold; verify against current guidelines and primary literature. Risk factors: M-protein ≥ 1.5 g/dL, non-IgG isotype, abnormal serum free light-chain ratio. Always exclude end-organ damage (CRAB) before calling it MGUS.