EFFECTS OF FREE GLYCEROL CONTAINED IN INTRAVENOUS FAT EMULSION ON PLASMA TRIGLYCERIDE DETERMINATION

Background: Plasma triglyceride analyses to evaluate Me clearance of T V fat emulsion are necessary in patients receiving parenteral nutritio n. Enzymatic kits for triglyceride analysis measure the glycerol that is hydrolyzed from triglyceride. This study investigates the effect of fat emulsion free glycerol on plasma triglyceride determination. Meth ods: Venous blood from fasting volunteers (n = 10) was drawn into tube s containing EDTA and was centrifuged to separate the plasma. An IV fa t emulsion containing 2.25% glycerol was added to plasma samples to cr eate serial dilutions ranging from 0.049% to 0.245% final lipid concen tration. Total triglyceride and free glycerol concentrations were dete rmined in each dilution and control sample. The free glycerol concentr ation was subtracted from the total triglyceride concentration to yiel d a true triglyceride value. Results: Increasing concentrations of fat emulsion added to donor plasma produced increases in total triglyceri de and free glycerol concentrations. The increase in free glycerol con centration produced significant concentration-related differences betw een total and true triglyceride concentrations. Conclusions: The total triglyceride lever overestimated the true triglyceride concentration due to fat emulsion free glycerol. To assure reliable triglyceride res ults in patients receiving fat emulsion, blanking for free glycerol sh ould be considered.