RESUMO
Despite comparable rates of hemolysis, only 50% of patients with sickle hemoglobinopathy (SH) develop pigment gallstones by age 20 yr. Thus, pathogenetic factors, other than hemolysis, may contribute to gallstone formation. In the present study we determined whether gallbladder function, measured by real-time ultrasonography or bile acid metabolism, determined by isotope dilution-mass spectrometry, were altered in adolescents and young adults with SH. Compared with healthy controls, SH subjects had larger fasting (27 +/- 16 vs. 15 +/- 5 ml, p less than 0.02), and residual (8 +/- 6 vs. 4 +/- 2 ml, p less than 0.03) volumes of the gallbladder, but similar rates of emptying (0.029 +/- 0.016 vs. 0.034 +/- 0.029 min-1) and percentage of fasting volume emptied (71% +/- 13% vs. 72% +/- 14%). In SH subjects, the volume and emptying of the gallbladder were similar between those with and without gallstones. Some SH subjects had stasis of bile within the gallbladder, as demonstrated by isotopic disequilibrium between the circulating bile acid pool and bile stored in the gallbladder. Subjects with SH with gallstones tended to have smaller bile acid pools than SH subjects without gallstones (81 +/- 11 vs 163 +/- 91 mumol/kg, p = 0.051). We conclude that adolescents and young adults with SH have enlarged gallbladders that retain an increased postprandial volume of bile. Bile retention within the gallbladder may lead to stasis and contribute to the pathogenesis of pigment gallstones.
