How to handle lipemic CBC samples on Sysmex hematology analyzers?

Objectives: Lipemia poses a significant preanalytical problem for complete blood count (CBC) measurement due to limited and non-standardized methods for recognition and removal. We aimed to verify the optical hemoglobin (Hb-O) measurements on the Sysmex XN-1000 hematology analyzer (HA) as a possible reliable method for managing lipemic CBC samples.

Methods: Ninety CBC samples with varying Hb concentrations were gradually spiked with a lipid emulsion. Measurements were repeated and Hb-O concentrations were recorded. Spiked CBC samples were centrifuged (400 g/10 min). Plasma was carefully removed, and Hb concentration was measured. The values obtained from the lipemic samples were adjusted according to the measurements in the plasma. The removed plasma was substituted with the analyzer's diluent, and measurements were repeated. Triglyceride concentrations were measured in lipemic plasma samples.

Results: Hb-O showed statistically insignificant and acceptable bias compared to the initial Hb measurement according to the strictest acceptability criteria (-0.4 %, 95 % CI: -1.2-0.3, p=0.2447). The observed bias did not correlate with the degree of lipemia (rho=-0.072, 95 % CI: -0.295 to 0.157, p=0.537). Hemoglobin measured in samples with lipemic plasma replaced by analyzer diluent exhibited minimal, albeit statistically significant, bias (-1.1 %, 95 % CI: -2.0 to (-0.1), p=0.025). The observed bias negatively correlated with the degree of lipemia (rho=-0.369, 95 % CI: -0.550 to (-0.155), p=0.001). The highest unacceptable bias was found in the recalculated hemoglobin values based on the measured plasma hemoglobin (-3.5 %, 95 % CI: -4.1 to (-2.9), p<0.0001).

Conclusions: Hb-O measurement is the most reliable measure of lipemia removal in CBC samples on the Sysmex XN-1000 HA.