Choline deficiency causes reversible hepatic abnormalities in patients receiving parenteral nutrition: proof of a human choline requirement: a placebo-controlled trial

BACKGROUND

Previous studies have shown that plasma free choline concentrations are significantly decreased in many long-term home total parenteral nutrition (TPN) patients. Furthermore, low choline status has been associated with both hepatic morphologic and hepatic aminotransferase abnormalities. A preliminary pilot study suggested choline-supplemented TPN may be useful in reversal of these hepatic abnormalities.

METHODS

Fifteen patients (10 M, 5 F) who had required TPN for > or =80% of their nutritional needs were randomized to receive their usual TPN (n = 8), or TPN to which 2 g choline chloride had been added (n = 7) for 24 weeks. Baseline demographic data were similar between groups. Patients had CT scans of the liver and spleen, and blood for plasma free and phospholipid-bound choline, alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase, gamma glutamyl transferase (GGT), bilirubin, serum lipids, complete blood count (CBC), and chemistry profile obtained at baseline, and weeks 2, 4, 6, 12, 16, 20, 24, and 34. CT scans were analyzed for Hounsfield unit (HU) densities.

RESULTS

There were no significant differences in any measured parameters after 2 weeks. However, at 4 weeks, a significant difference in liver HU between groups was observed (13.3+/-5.0 HU [choline] vs 5.8+/-5.2 HU [placebo], p = .04). This significant trend continued through week 24. Recurrent hepatic steatosis and decreased HU were observed at week 34, 10 weeks after choline supplementation had been discontinued. A significant increase in the liver-spleen differential HU was also observed in the choline group (10.6+/-6.2 HU [choline] vs 1.3+/-3.3 HU [placebo], p = .01). Serum ALT decreased significantly (p = .01 to .05) in the choline group vs placebo at weeks 6,12, 20, and 24. Serum AST was significantly decreased in the choline group by week 24 (p = .02). The serum alkaline phosphatase was significantly reduced in the choline group at weeks 2, 12, 20, 24, and 34 (p = .02 to 0.07). Total bilirubin was normal in these patients and remained unchanged during the study. Serum GGT tended to decrease more in the choline group, but the greater decrease was not statistically significant.

CONCLUSIONS

Choline deficiency is a significant contributor to the development of TPN-associated liver disease. The data suggest choline is a required nutrient for long-term home TPN patients.

Plasma choline concentrations in children requiring long-term home parenteral nutrition: a case control study

BACKGROUND

Low plasma free choline concentration has been associated with elevated serum hepatic aminotransferase concentrations and hepatic steatosis in adults who need home parenteral nutrition (HPN). We sought to determine if plasma free choline is similarly reduced in children who need home total parenteral nutrition (TPN).

METHODS

We compared the plasma free choline concentration in 21 children who required long-term HPN with 31 normal controls. Patients had received HPN for 75 +/- 13 (SD) months (range 3-206 months). All control children ingested a normal, mixed, nonvegetarian diet.

RESULTS

The mean plasma free choline concentration in the children receiving HPN was significantly lower than normal children (6.6 +/- 4.3 vs 8.0 +/- 2.3 nmol/mL, p = .002). Plasma free choline concentration was correlated with age (r = -0.43, p = .049). Using multiple linear regression analysis for age, sex, and squared age (considered in order to account for possible nonlinearity between choline and age), HPN children showed a steady and significant decline in plasma free choline concentration with increased age at the rate of 0.03 nmol/mL per month. Plasma lipid bound choline concentration did not vary with age. No relationship was seen between either plasma free and lipid bound choline concentration and amount of daily IV lipid infusion. A significant negative correlation was observed between plasma free choline concentration and aspartate aminotransferase (AST) and alanine aminostransferase (ALT) (r = -0.72, p = .04 and r = -0.80, p = .02, respectively).

CONCLUSION

Our data support the notion that patients who need long-term HPN without significant enteral feeding have a significant risk for the development of choline deficiency with its associated hepatic dysfunction.

The effect of choline supplementation on hepatic steatosis in the parenterally fed rat

Information regarding hepatic function during total parenteral nutrition in rats is often extrapolated to the clinical situation, but the steatosis observed in that species may simply reflect choline deficiency and be irrelevant to man. The effect of choline supplementation on hepatic lipid content and triglyceride secretion was examined in parenterally fed rats. Eighty to 90-day-old rats were randomized into three groups; group I received oral Purina Chow ad libitum, groups II and III received identical total parenteral nutrition regimens with the exception that group III received supplemental choline. After 7 days, peripheral triglyceride uptake was inhibited with Triton WR1339, the rate of secretion of 14C-labeled triglyceride measured after a bolus injection of 1-14C-palmitic acid, and total hepatic lipid content was measured. Total hepatic lipid content was elevated in group II (86.3 mg/g) and group III (83.3 mg/g), and both differed significantly from the control group I (35.2 mg/g, p less than 0.01), but the choline supplementation appeared to make no difference. Hepatic secretion of 14C-palmitic acid as 14C-triglyceride was reduced in group II (0.73%/ml plasma), and group III (0.72%/ml plasma) compared to group I (1.06%/ml plasma, p less than 0.05), and was unaffected by choline. The hepatic steatosis produced in the parenterally fed rat did not appear to be due to choline deficiency but to some other factors which may be important in man.

Microsomal phosphatidylethanolamine methyltransferase: inhibition by S-adenosylhomocysteine

Inhibition by S-adenosylhomocysteine (AdoHcy) of the three reactions of phosphatidylethanolamine methyltransferase which catalyzes the production of phosphatidylcholine from phosphatidylethanolamine in guinea pig and rat liver microsomes has been evaluated. Five of the six methylation reactions in these two species exhibit greater affinity for inhibitor, AdoHcy, than for substrate, S-adenosylmethionine (AdoMet). The Ki values for the rate-limiting reactions were 3.8 microM and 68 microM in rat and guinea pig livers, respectively. An AdoMet : AdoHcy ratio of 12 : 1 in developing liver was found to decline to a constant value in the adult of 5 : 1. The concentration of AdoHcy in rat and guinea pig liver increases markedly following death of the animal. A concomitant decrease in the AdoMet level was observed in guinea pig liver. A comparison of phosphatidylethanolamine methyltransferase activity with the hepatic concentrations of AdoMet and AdoHcy in mouse, rat, rabbit and guinea pig is presented. Regulation of the methylation pathway is discussed.