Interpreting Abnormal SPEP – Is It Just MGUS?

Monoclonal gammopathy of undetermined significance (MGUS) is a common but often confusing finding on serum protein electrophoresis (SPEP) reports. In this HemeTalks episode, Drs. Rahma Warsame and Jason Chen discuss how to interpret abnormal SPEP results, evaluate patients with suspected MGUS, and differentiate between benign and concerning findings. Using real-world cases, they highlight key clinical decision points, follow-up strategies, and how to communicate results with patients effectively. Tune in for expert guidance on navigating this diagnostic gray zone in hematology.

Learning Objectives:  

1. Recognize the clinical significance of MGUS and how it is detected 
2. Understand how to interpret MGUS lab testing results in the context of monoclonal gammopathies 
3. Identify when to refer, monitor, or investigate further in patients with MGUS

Clinical Pearls:

1. MGUS is a premalignant condition that is a diagnosis of exclusion. It is defined by the presence of a serum monoclonal protein (M-protein) less than 3 g/dL, bone marrow plasma cellsl <10%, and no end organ damage (CRAB) 
2. MGUS can progress to multiple myeloma, AL amyloidosis, Waldenstrom’s macroglobulinemia 
3. Confirmatory tests for MGUS include: SPEP, FLC assay, and bone marrow (only if high risk features are present.