Quantification of lipoprotein X and its relationship to plasma lipid profile during different types of parenteral nutrition.

ABSTRACT

An abnormal lipoprotein (LP), detected in plasma during total parenteral nutrition, has been shown to be similar to LPX observed in cholestasis and in familial lecithin-cholesterol-acyl-transferase (LCAT) deficiency. However, the conditions which facilitate the appearance of LPX during total parenteral nutrition are unclear; potential determining factors could be lipid input, plasma lipid levels, and/or inhibition of LCAT activity. An investigation was conducted on 12 patients receiving total parenteral nutrition for 3 wk by simultaneously evaluating plasma LPX (via a quantitative method) as well as total cholesterol, phospholipids (PL), triglycerides (TG), apolipoprotein B, and LCAT activity. Daily total nonprotein calories (40 kcal/kg body weight) and nitrogen input (250 mg/kg body weight) were fixed in this study. Three 7-day periods were defined during periods 1 and 3, lipid emulsion (10 or 20% Intralipid) and glucose were given as nonprotein calories (glucose-lipid periods); in period 2, glucose was administered alone as the sole source of nonprotein energy (glucose period) so that the total energy input was not modified. During periods 1 and 3, the patients were randomly assigned to receive either 9 g (period 1) and 12 g (period 3) of PL/day for 7 days, or 12 and 9 g of PL/day. By infusing either 10 or 20% Intralipid, TG input was varied concomitantly so that the subjects received 75, 100, or 150 g/day in periods 1 and 3. During the glucose-lipid periods, plasma LPX was measurable from the 2nd day and increased progressively. Its increment was closely related to a rise in unesterified cholesterol and PL (r = 0.7; p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)