Determination of serum apo A-IV concentration in patients receiving total parenteral nutrition

Serum apolipoprotein (apo) A-IV levels were determined in patients receiving total parenteral nutrition (TPN) by an immunoassay using a specific antiserum against apo A-IV purified from human sera. The value was significantly lower than that of normal subjects (p less than 0.001), and the level correlated significantly with the duration of TPN. In a patient receiving TPN, serum apo A-IV concentration decreased during TPN and returned to normal levels after resuming oral intake of diet. This finding indicates that serum apo A-IV is a new parameter for nutritional assessment, since the protein is exclusively synthesized in the gut, being different from other rapid turnover proteins which are mainly synthesized in the liver.