Spurious Biochemical Results in Plasma Cell Neoplasms: An Observational Study from a Regional Cancer Center

Introduction Plasma cell neoplasms are characterized by the production of paraproteins. These paraproteins can interfere with routine biochemical assays performed using conventional wet chemistry platforms, leading to erroneous results, misinterpretation, and delays in diagnostic evaluation. Objective The objective of this study is to investigate the extent of interference caused by monoclonal proteins (M-proteins) in calcium, magnesium, and phosphate assays, and to quantify the degree and significance of such interference. Methods This is an observational case–control study. Test samples containing M-proteins and control samples without M-proteins were analyzed using both wet chemistry and dry chemistry methods in parallel. Data were evaluated using paired t-tests in the test group and unpaired t-tests in the control group. Passing–Bablok regression and Bland–Altman difference plots were employed to assess method comparison and agreement. Results Control samples without paraproteins demonstrated no significant method-related differences in calcium and magnesium assays, whereas a minor method difference was observed for phosphate. In contrast, test samples containing paraproteins exhibited statistically significant interference in calcium, magnesium, and phosphate assays when analyzed using conventional wet chemistry methods. Discussion Paraproteins can significantly interfere with biochemical assays ( p < 0.05) performed using traditional wet chemistry analyzers. In comparison, dry chemistry platforms demonstrate greater resilience to such interference, thereby offering a more reliable alternative for minimizing paraprotein-induced assay variability in patients with plasma cell neoplasms. Conclusion These findings suggest that dry chemistry may serve as a suitable alternative to conventional wet chemistry for minimizing paraprotein-related assay interference.