What is the most appropriate course of action when a lipemic sample gives varying sodium results based on dilution methods?

When dealing with a lipemic sample that produces varying sodium results based on different dilution methods, the best course of action is to report the undiluted ion-selective electrode (ISE) result. This approach is justified because the ISE method is specifically designed to measure the concentration of ions in a solution, and it should provide the most accurate representation of the sodium level in the sample.

Lipemia can interfere with the accuracy of some analytical methods due to the presence of triglycerides, leading to discrepancies in results based on how the sample is processed. Reporting the undiluted ISE result allows for a true measurement without the complications introduced by dilution, particularly since different dilution factors may exacerbate variations caused by the lipemic interference.

Choosing to ultracentrifuge the sample and then repeat by ISE might be a viable alternative, but it requires additional processing time and resources, and may not guarantee more accurate results than simply using the ISE on the undiluted sample. Reporting a sodium result based on a standard dilution or arbitrary numeric value could misrepresent the actual concentration, and diluting the sample further could mask the true ion concentration.

In summary, the recommendation to report the undiluted ISE result prioritizes accuracy and practicality in the face