Introduction: Fully automated biochemical analyzers may fail to detect veiled preanalytical anomalies when relying solely on barcode-based systems.This report describes an instance of pseudohyponatremia caused by marked hyperproteinemia in a patient with multiple myeloma, emphasizing the preanalytical, analytical, and communication lessons learned.Case description: A 65-year-old male with known multiple myeloma and hypertension presented with fever and dyspnea.During admission, repeated analyzer processing failures were encountered.The NT-pro brain natriuretic peptide (BNP) assay failed on both the QUIDEL Triage MeterPro and the VITROS 3600 analyzer, with persistent aspiration failure errors.Initial laboratory investigations revealed pancytopenia and elevated inflammatory markers.Serum sodium measured by an indirection-selective electrode (ISE) on the Beckman Coulter AU700 analyzer was 120 mmol/L.However, arterial blood gas (ABG) analysis using direct ISE (GEM 3000 analyzer) showed a sodium level of 136 mmol/L, raising suspicion of analytical interference.Given the repeated aspiration failures across multiple platforms, preanalytical and sample-related factors were considered.Correlation with clinical history revealed that the patient was a known case of multiple myeloma.Subsequent estimation of total protein demonstrated marked hyperproteinemia (18 gm/dL).The severe hyperproteinemia likely resulted in increased serum viscosity, causing aspiration resistance and impaired sample flow within the analyzers.This interference was not recognized during the initial chemistry analysis.Retrospective review confirmed pseudohyponatremia secondary to hyperproteinemia.Unfortunately, the patient succumbed on the following day, precluding further evaluation.Discussion: Extreme hyperproteinemia can cause both preanalytical and analytical interference, in which the hyperviscosity may impair the sample aspiration, while the indirect ISE method underestimates sodium due to the well-known electrolyte exclusion effect.Modern automated systems enhance efficiency and standardization but may inadvertently reduce the likelihood of identifying subtle, veiled preanalytical errors that could have been detected during conventional manual handling.Active communication between clinicians and laboratory professionals was crucial in identifying the interference.Correlating laboratory data with ICU ABG reports offers an additional layer of verification and may uncover hidden or subtle preanalytical errors not evident through automated analysis alone.Conclusion: This case highlights that pseudohyponatremia and hyperviscosity-related analyzer errors may go unrecognized in automated systems.A meticulous manual inspection, confirmation using direct ISE measurement, and close laboratory-clinician collaboration are essential for accurate result interpretation.
Kunnath et al. (Sun,) studied this question.