BILE-ACID KINETICS AND BILIARY LIPID-COMPOSITION IN CYSTIC-FIBROSIS

Aims/Methods: Bile acid kinetics and biliary lipid composition were st udied in seven patients, aged 17-70 years with cystic fibrosis. All pa tients were of normal height and weight, and were in good clinical con dition. Ultrasonography indicated a small gallbladder in one and non-v isualized gallbladder in two patients. Serum concentrations of cholest erol and transaminases were essentially normal. Substitution with panc reatic enzymes was discontinued at least 1 week before the investigati on. Bile acid kinetics were determined by the isotope dilution techniq ue using [24-C-14] cholic and [24-C-14] chenodeoxycholic acids. Result s: 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 mu mol/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 mu mol . k g . 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 value s were not significantly different from controls, aged 21 to 68 years. The biliary lipid composition of fasting gallbladder bile showed a lo w-normal molar percentage of cholesterol, and in no case was bile supe rsaturated. The duodenal bile acid concentration was similar in patien ts and controls, but the bile acid distribution was significantly diff erent; cholic acid constituted a higher percentage (p<0.001) and cheno deoxycholic and deoxycholic acid lower percentages (p<0.05 and p<0.01, respectively) in cystic fibrosis patients than in controls. Conclusio ns: The findings of normal concentrations of bile acids in duodenal bi le and normal to large pool sizes of bile acids in all patients, despi te a marked fat malabsorption, are in contrast to some previous report s. The data indicate that biliary lipid metabolism is normal in well-n ourished and well-controlled adult patients with cystic fibrosis.