ABSTRACT Background IgM paraproteins frequently cause spurious results in biochemical assays; however, standardized strategies to eliminate such interference remain limited. This study systematically compares four dilution matrices to identify effective methods for correcting IgM‐mediated interference in prealbumin (PA) and uric acid (UA) measurements. Methods Two cases of IgM‐type monoclonal gammopathy (IgM‐κ: 5.37 g/L; IgM‐λ: 25.8 g/L) presenting with spurious PA and UA results were investigated. Four interference‐mitigation strategies were evaluated: dilution with deionized water, 0.9% saline, 18% hypertonic saline, and prealbumin reagent 1 containing polyethylene glycol (PEG). Analytical performance was assessed using recovery rates, result stability across dilution factors, and reaction curve analysis. Results For PA measurement, dilution with prealbumin reagent 1 (2‐fold) or deionized water (3‐fold) effectively eliminated IgM interference, restoring results to clinically plausible concentrations with recovery rates of 101.4% and 99.5% in control samples. For UA measurement, optimal correction was achieved using 18% hypertonic saline (2‐fold) or deionized water (3‐fold), yielding recovery rates of 101.6% and 102.8%, respectively. Higher dilution factors resulted in reduced analytical reliability in IgM‐positive samples but not in controls. Conclusions Effective elimination of IgM paraprotein interference requires assay‐specific pretreatment strategies. PEG‐based dilution is optimal for PA immunoturbidimetric assays, while osmotic modulation with hypertonic saline is most effective for UA measurement. Deionized water dilution provides a practical, broadly applicable alternative. These simple protocols are suitable for routine clinical laboratory implementation.
Chi et al. (2026) studied this question.