The role of
cholestasis and ileal dysfunction on
sterol metabolism was studied in 79 patients with
inflammatory bowel diseases (IBDs) and in 23
irritable bowel syndrome (IBS) controls by determining serum
sterol/
cholesterol proportions. The
sterols included
cholesterol precursors (delta 8-cholestenol,
desmosterol and
lathosterol), markers of
cholesterol synthesis,
cholestanol and
plant sterols (
campesterol and
sitosterol), markers of
cholesterol absorption and biliary secretion. The IBD patients were subgrouped into distal
ulcerative colitis (dUC, n = 21), pancolitis (pUC, n = 29), ileal
Crohn's disease (iCD, n = 20) and colonic
Crohn's disease (cCD, n = 9). The
cholestanol proportions were increased in the 3 colonic IBD groups, up to two times in cCD patients and seven times in a case with clinically overt
primary sclerosing cholangitis, but were within the control IBS levels in the patients with iCD. The
sitosterol, but not
campesterol, proportion was significantly increased only in the pUC group. In the iCD group only the serum precursor
sterol proportions, especially those for delta 8-cholestenol and
lathosterol, were elevated probably due to ileal dysfunction induced
bile acid malabsorption and compensatorily increased
cholesterol synthesis. In conclusion, the findings suggest that the increased
cholestanol proportion in colonic IBD is determined mainly by impaired biliary elimination of this
sterol, while in ileal affision the dominating change in
sterol balance is activated
cholesterol synthesis. Thus increased serum
cholestanol is a novel finding in colonic IBD, apparently indicating the presence of subclinical
cholestasis in a marked number (20-50%) of IBD patients.