A proposed cause for the hepatic dysfunction associated with parenteral nutrition.

Total parenteral nutrition (TPN) is associated with cholestasis and hepatic steatosis, which can be lethal in infants who cannot be fed orally. It was determined that route of administration was not the critical variable in the development of hepatic steatosis. Two groups of young rats received equivalent amounts of a standard TPN solution either orally or intravenously for an 8- to 10-day period during which they received no other nutrition. Both groups gained equivalent weight and developed marked hepatic steatosis. To test whether the solution was toxic or deficient, three groups of rats were given TPN solution orally and a fraction of their usual daily intake of rat chow. Rats receiving less than 10% of their usual chow intake developed steatosis; rats receiving more than that did not. To determine the solubility of the protective material in chow, two groups of rats were given TPN solution orally and chow that been extracted with either water or the organic solvent chloroform. Rats eating the water-extracted chow developed steatosis, rats eating chloroform-extracted chow did not. Although the protective component in chow was apparently water soluble, addition of a water soluble extract of chow to the TPN solution fed another two groups of rats did not prevent steatosis at 0.1 mg/mL and only partially, if at all, at 10 mg/mL. TPN-related hepatic dysfunction, as measured by the development of hepatic steatosis in this model, may be due to a deficiency in the TPN solution. The missing constituent(s) appears to be present in rat chow and can be extracted with water, but not with an organic solvent.