Proctocolectomy modifies the enterohepatic circulation and activity of bacteri al enzymes depending on the structure of the stoma and function of the terminal ileum. We evaluated in our comparative study effects of different colectomy cons tructions on cholesterol metabolism. Levels of lipoprotein cholesterol and trigl ycerides, noncholesterol sterols, and squalene in serum, fecal fat, and bile aci ds, cholesterol absorption efficiency, and cholesterol metabolism by sterol bala nce technique were analyzed in human subjects with ileal pouch-anal anastomosis (n=34), conventional ileostomy (n =8), ileorectostomy (n =6), and controls (n = 29). Malabsorption of bile acids, but not of fat, and low serum levels of total and low-density lipoprotein cholesterol, but high levels of high-density lipop rotein cholesterol and increased cholesterol synthesis were evident in the colec tomy groups. In contrast to the ileorectostomy group, expressing high absorption and biliary secretion of cholesterol, a low cholesterol absorption percentage a ccompanied by elevated serum proportions of cholesterol precursor sterols and ph ytosterols characterized the ileal pouch-anal anastomosis and conventional ileo stomy groups. After colectomy, fecal excretion of secondary bile acids was low, wher eas relative proportions of identifiable bile acids remained the same in each st udy group. Low serum levels of total and lowdensity lipoprotein cholesterol of c olectomized subjects may decrease the risk of premature atherosclerosis. The fav orable serum lipid profile was due to enhanced fecal loss of cholesterol as bile acids despite abnormally high cholesterol synthesis. Ileal dysfunction probably diminished cholesterol absorption in subjects with ileal pouch-anal anastomosi s and conventional ileostomy, with no explanation for those with ileorectostomy with no clinical gastrointestinal dysfunction. Relative synthesis of identifiabl e primary bile acids remained unchanged postoperatively, but formation of second ary bile acids was weak due to scarce bacterial flora.
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