Absence of significant role of bile acids in diarrhea of a heterogeneous group of postcholecystectomy patients

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Abstract
Twenty-five postcholecystectomy (PC) patients who underwent a diagnostic work-up for persistent diarrhea and six control subjects were studied. Fourteen of the 25 patients were also characterized by conditions other than PC which could play a role in the pathogenesis of the diarrhea. However, none of the patients had evidence of ileal disease or resection. The average follow-up of the patients after the study was approximately 4.4 years. Excretion, composition, and aqueous-phase concentrations of fecal bile acids were analyzed using gas-liquid chromatography. Eleven of the 25 PC patients showed an increased fecal bile acid excretion. In three of the 11 patients, the magnitude of the bile acid loss, which ranged from 2.26 to 3.34 mmol/24 hr, indicated the presence of severe bile acid malabsorption. The fecal bile acid composition showed a significant shift from secondary to primary bile acids. In spite of the presence of marked bile acid malabsorption, the aqueous-phase concentrations of the dihydroxy bile acids, chenodeoxycholic and deoxycholic acids, did not, with one exception, reach the secretory level of 1.5 mM. The relatively low aqueous concentrations were the result of low bile acid solubility, due to an acidic fecal pH. Only two of nine patients, one with severe, and the other with equivocal bile acid malabsorption, who were treated with cholestyramine, showed an improvement of the diarrhea. The findings of subsecretory bile acid concentrations in the fecal aqueous phase and of inconsistent therapeutic responses to cholestyramine indicate that, in spite of the presence of bile acid malabsorption, the diarrhea was, with few exceptions, not bile acid-induced. The results of the study also suggest that the diarrhea in many PC patients is multifactorial in origin.