Reflex Triglyceride Testing in Samples with Elevated Lipemia Index Enables Incidental Detection of IgM Monoclonal Proteins: A Large Real-World Laboratory Study

This study investigates the diagnostic potential of elevated lipemic index for detecting IgM monoclonal proteins in routine clinical laboratory samples. Based on more than 200,000 samples, the findings demonstrate that reflex triglyceride testing can help distinguish genuine lipemia from IgM M-protein interference. A triglyceride cut-off of <3.82 mmol/L in samples with a lipemic index ≥125 mg/dL achieved 97.4% sensitivity and 97.2% specificity. This approach enabled the incidental detection of 86 previously unrecognized cases of IgM monoclonal gammopathy and provides a practical strategy for improving laboratory diagnostics.