Establishment and Application of a Quantitative Lipemia Index as a Novel Indicator for Assessing Lipemic Interference in Clinical Chemistry.

BACKGROUND

Lipemia is a common pre-analytical interference in clinical chemistry. Triglyceride (TG) concentration is commonly used as a surrogate indicator for lipemic interference, but its predictive reliability is limited by heterogeneity in lipoprotein particle composition. This study aimed to establish and validate a quantitative Lipemia index (LI) assay for direct measurement of serum turbidity, compare its predictive value with TG, and evaluate its clinical applicability through reference interval estimation and correlation with interference deviations in native patient samples.

METHODS

The LI assay was developed on a Beckman Coulter AU5800 analyzer by measuring ΔA (A660-A800 nm). Performance was validated per CLSI guidelines: precision (EP05-A3), detection capability (EP17-A2), linearity (EP06-ED2), method comparison (Passing-Bablok regression, Bland-Altman analysis), reference interval (EP28-A3c), and dilution recovery (EP07-A2). LI's predictive value for lipemic interference was compared to TG using deviations in total protein assays (single- vs. double-reagent methods).

RESULTS

The LI assay demonstrated precision with CV ≤ 2.23% and linearity (0.05-30.87 mmol/L TG-equivalent). It correlated strongly with the reference TG method (ρ = 0.998, p < 0.0001). In predicting assay interference, LI showed a closer correlation with total protein deviations than did TG (rs = 0.822 vs. 0.770). A reference interval of 0.093-0.240 was established for healthy adults. Dilution recovery (90%-110%) confirmed accuracy.

CONCLUSIONS

The quantitative LI assay provides a standardized, clinically validated measure of lipemic interference aligning more directly with the optical nature of clinical chemistry testing than TG measurement. These findings support its analytical validity, utility as a predictor of turbidity interference, and clinical applicability.