• Jerzy W Naskalski, Bogdan Solnica, and Wojciech Gernand.
• Diagnostic Department, Collegium Medicum Jagiellonian University, Kraków, Poland. mbnaskal@cyf-kr.edu.pl
• Clin Lab. 2007 Jan 1; 53 (7-8): 441-7.

BackgroundNa+ and K+ concentration measurements by ion-selective electrodes and flame photometry are affected by lipids influencing plasma water content.MethodsIn 166 sera with total cholesterol ranging from 1.19 to 23.3 mmol/L, and triglycerides ranging from 0.34 to 56.3 mmol/L, Na+ and K+ concentrations were assayed using flame photometry and direct ion-selective electrodes of the Vitros 950 analyzer. Linear regression analysis was used to examine inter-method difference as lipid content variable.ResultsIn hypercholesterolemia and hypertriglyceridemia flame photometry yielded Na+ concentrations lower by 1.85% and 2.15% than ion-selective electrode measurements (p < 0.05). Na+ concentration inter-method difference correlated with total cholesterol and triglycerides. In bivariate analysis, inter-method difference significantly depended on total cholesterol (r2 = 0.09), whereas the impact of triglycerides was weak. In trivariate analysis, total cholesterol had the highest impact (r2 = 0.12), followed by Na+ concentration (r2 = 0.04), while the impact of triglycerides was insignificant. Recognition of hypernatremia significantly depended on total cholesterol (chi2 p = 0.0017); 27% of samples with hyperlipidemia (total cholesterol > 5.2 mmol/L, triglycerides > 2.5 mmol/L) classified as normonatremia by flame photometry presented hypernatremia by direct ion-selective electrode.ConclusionsThe lipid status of patients influences recognition of hypernatremia if assays are based on total plasma volume. No effect of lipids was observed on the recognition of hyperkalemia.

15 keywords...

hide…