Human plasma lipoproteins and total parenteral nutrition with intravenous fat emulsion

Lipoprotein concentration and composition before and after Intralipid infusion were investigated in seven adult surgical patients receiving continuous total parenteral nutrition. Plasma samples were obtained prior to parenteral alimentation, after 7 days of glucose/amino acid solution without Intralipid, and again following 5 days of daily Intralipid. Cholesterol, triglyceride, protein, and phospholipid concentrations were determined on very low-, low-, and high-density lipoprotein from each specimen. After Intralipid very low-density lipoprotein concentration fell to 29% (p less than 0.015) of pre-Intralipid levels. There was no substantial increase in low-density lipoprotein phospholipid post-Intralipid to suggest the presence of lipoprotein-X. Plasma total triglyceride levels declined by 33% after Intralipid (p less than 0.01) and plasma total cholesterol levels rose by 40% (p less than 0.02). In our patients, in whom metabolic mechanisms were not saturated, it would appear that Intralipid was metabolized by activated lipoprotein lipase pathways, without the appearance of hyperlipidemia or abnormal lipoproteins.