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Bile acid kinetics and biliary lipid composition in cystic fibrosis
B Strandvik1, K Einarsson, A Lindblad
1Department of Pediatrics, Faculty of Medicine, Göteborg University, Sweden.
Aims/Methods:
Bile acid kinetics and biliary lipid composition were studied in seven patients, aged 17-70 years with cystic fibrosis. All patients were of normal height and weight, and were in good clinical condition. Ultrasonography indicated a small gallbladder in one and non-visualized gallbladder in two patients. Serum concentrations of cholesterol and transaminases were essentially normal. Substitution with pancreatic enzymes was discontinued at least 1 week before the investigation. Bile acid kinetics were determined by the isotope dilution technique using [24-14C] cholic and [24-14C] chenodeoxycholic acids.
Results:
The mean pool size of cholic acid was 3.3 (range 0.8-6.9) mmol, and that of chenodeoxycholic acid 2.3 (1.2-2.7) mmol, corresponding to 49 +/- 16 and 36 +/- 4 mumol/kg, respectively. The mean synthesis of cholic acid was 1.3 (0.5-3.6) mmol/day and of chenodeoxycholic acid 0.8 (0.2-1.7) mmol/ day and related to body weight 20 +/- 6 and 12 +/- 3 mumol.kg.day-1, respectively. Fractional turnover rates averaged 0.48 (0.24-0.67) and 0.36 (0.10-0.65) day-1, respectively. The kinetic values were not significantly different from controls, aged 21 to 68 years. The biliary lipid composition of fasting gallbladder bile showed a low-normal molar percentage of cholesterol, and in no case was bile supersaturated. The duodenal bile acid concentration was similar in patients and controls, but the bile acid distribution was significantly different; cholic acid constituted a higher percentage (p < 0.001) and chenodeoxycholic and deoxycholic acid lower percentages (p < 0.05 and p < 0.01, respectively) in cystic fibrosis patients than in controls.
Conclusions:
The findings of normal concentrations of bile acids in duodenal bile and normal to large pool sizes of bile acids in all patients, despite a marked fat malabsorption, are in contrast to some previous reports. The data indicate that biliary lipid metabolism is normal in well-nourished and well-controlled adult patients with cystic fibrosis.