Abstract
To study the effect of total parenteral nutrition (TPN) on biliary lipids in critically ill neonates, biliary lipid concentrations were determined in 13 neonates before starting TPN, in 8 receiving TPN for up to 2 weeks and in 9 receiving TPN for up to 8 weeks. Bile was very dilute in the 13 neonates not receiving TPN owing to a low concentration of bile acids. In many the bile-acid concentration was below the critical micellar concentration, thus cholesterol in bile was not dissolved. The neonates receiving TPN for up to 2 weeks showed a marked increase in bile-acid content and had levels above the critical micellar concentration. This apparently beneficial effect of TPN disappeared after 2 weeks and neonates who received TPN for 3 to 8 weeks again had bile-acid levels below the critical micellar concentration. Three conclusions may be drawn from this study: (a) in the fasting state before TPN is begun, the cholesterol content of bile relative to phospholipid and bile acids increased in linear fashion during the fasting period; (b) short-term TPN of up to 2 weeks' duration was associated with an increased bile-acid content to levels at which cholesterol could be dissolved; (c) neonates on long-term TPN and no oral intake secrete extremely dilute bile with an insufficient concentration of bile-acid molecules to form micelles to dissolve cholesterol. This finding may explain some of the adverse hepatobiliary changes associated with long-term administration of TPN.