Increased lipoprotein X causes hyperlipidemia during intravenous administration of 10% fat emulsion in man

To clarify the mechanisms of hyperlipidemia during intravenous Intralipid 10%, lipoprotein profiles including lipoprotein X were studied in 13 patients receiving 2.0 g of fat per kilogram per day by Intralipid 10% over a period of 8 weeks. All patients were fed exclusively by total parenteral nutrition providing 1.1 g of amino acid and 30 kcal/kg per day. Intravenous administration of Intralipid 10% caused a marked increase of low-density lipoprotein (LDL), phospholipid, and cholesterol, especially free cholesterol, whereas triglyceride, very-low-density lipoprotein, and high-density lipoprotein remained within the normal range. Lipid composition of LDL approximated that of lipoprotein X progressively with the intravenous Intralipid 10%. Quantification of lipoprotein X revealed that its increase was proportionate with that of LDL and total lipid. From these findings, hyperlipidemia during intravenous Intralipid 10% is induced almost exclusively by the increased lipoprotein X.