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)