Background-No data exist on cholesterol absorption in patients with an
ileoanal anastomosis (IAA). Aims-To study cholesterol absorption and
its effects on cholesterol and bile acid metabolism in patients with a
n IAA. Patients and methods-Cholesterol absorption, and serum, biliary
, and faecal lipids were studied in 24 patients with an IAA and 20 con
trols. Results-Fractional cholesterol absorption was significantly low
er in the patients (36% versus 47% in controls). Surprisingly, the cal
culated intestinal influx of endogenous cholesterol was reduced so tha
t the absolute absorption of cholesterol was decreased; elimination of
cholesterol as faecal neutral steroids remained normal. Thus, the sli
ghtly increased cholesterol synthesis was mainly due to increased faec
al bile acid excretion, which, in turn, was associated with reduced ab
sorption and biliary secretion of bile acids. Serum total and low dens
ity lipoprotein (LDL) cholesterol and LDL triglycerides were lower in
the patients. Molar percentage and saturation index of biliary cholest
erol were slightly higher in patients with an IAA. Proportions of seco
ndary bile acids in bile and faeces were diminished, and faecal uniden
tified bile acids were higher in patients. Conclusions-Cholesterol abs
orption is significantly impaired in patients with an IAA, and is clos
ely related to changes in serum and biliary Lipids observed in these p
atients.