Lipemia-induced pseudohyponatremia: Analytical bias beyond manufacturer claims

Background: Lipemia-induced sodium underestimation can introduce a clinically relevant analytic bias in sodium measurements. In this study, we aimed to evaluate the clinical impact of lipemia on sodium measurements, investigate thresholds for sodium underestimation due to lipemia, and compare manufacturer-recommended interference limits with actual clinical data. Methods: interference). The relationship between sodium bias (ΔNa) and lipemic index was assessed. Results: Intralipid®-spiked samples exceeded the analytical and CLIA limits at lipemic indices of ∼300 and ∼500, respectively, well below manufacturer-stated thresholds (>2000). In clinical samples, sodium bias was greater than in spiked plasma where ΔNa exceeded analytical limits at L-indices >100 and CLIA TEa at >200. Conclusions: interference experiments. We recommend that manufacturers update their interference studies, and that laboratories evaluate their lipemic thresholds through retrospective data analysis, in accordance with ISO 15189:2022.