INTRAVENOUS INTRALIPID 10-PERCENT VS 20-PERCENT, HYPERLIPIDEMIA, AND INCREASE IN LIPOPROTEIN-X IN HUMANS

To clarify the mechanisms of hyperlipidemia caused by infusion of Intralipid 10%, we compared lipoprotein metabolism during intravenous Intralipid 10% and Intralipid 20%, which contains only half the amount of egg yolk lecithin for the same content of triglyceride as intralipid 10%.Ten patients receiving 20 ml.kg-1.day-1 of Intralipid 10% and 10 receiving 10 ml.kg-1.day-1 of Intralipid 20% were fed exclusively by total parenteral nutrition (TPN) providing 1.1 g amino acid and 30 kcal.kg-1.day-1 for 4-6 wk. Intravenous Intralipid 10% caused a marked increase in low-density lipoprotein (LDL), together with increases in phospholipid and cholesterol, especially free cholesterol. The progressive increase in lipoprotein X was in proportion with that of LDL or total lipid, whereas no increase in lipids, LDL, or lipoprotein X was observed during intravenous Intralipid 20%. A significant increase in apolipoproteins CIII and E with Intralipid 10% also caused a rise in lipoprotein X. With Intralipid 20%, however, the alterations in apolipoproteins were not observed. Lecithin:cholesterol acyltransferase (LCAT) activity was significantly elevated with Intralipid 10 but not 20%. Disappearance of lipoprotein X after cessation of Intralipid 10% was relatively rapid, and the half-life was 24-60 h. From these findings, the hyperlipidemia with Intralipid 10% was caused almost exclusively by the increase in lipoprotein X. The excess lecithin may be responsible for the formation of and increase in lipoprotein X. Furthermore, it was revealed that Intralipid 20% could be safely used without inducing hyperlipidemia.