Abstract
Several investigators, including the authors, have demonstrated that patients receiving long-term total parenteral nutrition (TPN) have low plasma choline levels.1-3 In the present study, 15 patients who were receiving home TPN were randomly chosen from a group of long-term TPN patients found to have low levels of plasma free choline on initial screening.3
The patients received TPN for 7.0 ± 1.1 years (range, 1.5 to 12.5 years). Their TPN consisted of 2 to 3 liters of 15% to 25% dextrose solution with 3.5% to 4.25% amino acids, electrolytes, trace elements, and vitamins. Patients received 20.1 ± 2.2 kcal/kg per day actual body weight. Parenteral lipid supplied was 22 ± 5% of daily intravenous caloric intake (Intralipid 20%, Kabi-Vitrum, Alameda, CA).
Patients received either lecithin supplementation (20 g/12 hours in 2.5 tablespoons of soybean oil-based liquid) or placebo (2.5 tablespoons of oil) for 6 weeks in a double-blind fashion. Patients were evaluated at baseline and at 2 and 6 weeks. Laboratory measurements included plasma and red blood cell free choline, plasma and red blood cell phospholipid-bound choline, transaminases, alkaline phosphatase, bilirubin, cholesterol, high and low density lipoproteins, carnitine (total and free), and methionine. Free and phospholipid-bound choline levels were measured in bottles of Intralipid. Liver imaging was carried out by computed tomography (CT) scanning. Limited noncontrast CT scans of the liver and spleen were performed at 120 kV, 120 mA with a 3.0-second scan time. Multiple representative sections were examined and a mean CT number in Hounsfield units was determined by two methods, determination of the mean absolute liver CT number and the liver spleen differential, obtained by subtracting the average spleen CT number from the average liver CT number to correct for interscan variability. Data were analyzed statistically by comparing percent changes in blood tests at 2 and 6 weeks and absolute changes in Hounsfield units.
The full 6-week study was completed in 10 of the 15 patients. Eight of 15 subjects had fatty livers at baseline. Lecithin supplementation led to an increase in plasma free choline of 53.4% ± 15.4% at 2 weeks (p < .04), whereas the placebo group had no change at 2 weeks. A significant (p < .02) decrease in liver fat, indicated by the change in Hounsfield units was seen at 2 weeks in the lecithin-supplemented group (7.5 ± 1.7 units). No significant changes were seen in the placebo group.
The authors concluded that hepatic steatosis in many patients receiving long-term TPN is caused by plasma free choline deficiency and may be reversed with lecithin supplementation.
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