Reduced fecal sterol excretion in subjects with familial hypoalphalipoproteinemia

Abstract

Background Fecal bile acid and neutral sterol excretion are the obligate endpoints of the reverse cholesterol transport pathway (RCT). In studies in mice, no evidence was found for a relation between HDL-cholesterol (HDL-c) levels and fecal sterol excretion. In this study, we have evaluated this relationship in patients with isolated low HDL-c versus controls. Results Fecal sterol excretion was studied in 12 subjects with familial hypoalphalipoproteinemia (FHA) and 11 healthy controls. Compared to the controls (8.9 ± 6.3 mg/kg/day), neutral sterol excretion was significantly lower in the FHA group (4.0 ± 2.4 mg/kg/day). Fecal bile acid excretion showed a similar pattern. Across the groups, a strong positive correlation between HDL-c and fecal neutral sterol excretion was found ( r = 0.53; p = 0.01). Conclusions Isolated low HDL-c levels in humans are associated with reduced fecal sterol excretion suggesting that in humans HDL regulates the final step in the RCT pathway at low HDL-c levels.