Changes in cholesterol pool size, turnover rate, and fecal bile acid and sterol excretion after partial ileal bypass in hypercholesteremic patients

The behavior of the serum cholesterol specific activity-time decay curve before and for 2 months after partial ileal bypass in each of 7 hypercholesteremic patients was indicative of a marked increase in cholesterol turnover after operation. Using a two-compartment open mamillary system as the model of plasma cholesterol turnover, the calculated cholesterol turnover rate in 3 patients demonstrated a significant threefold increase one year after operation. Fecal steroid measurements, using the isotope balance method, showed a marked 3.8 fold increase in 3 patients restudied 2 months after ileal bypass (from 785 mg. per day before to 2,955 mg. per day after operation). There was a significant increase (2.7 fold) in neutral sterol excretion and an even greater increase (4.9 fold) in the bile acid excretion following operation. This effect was apparently persistent, as demonstrated in 2 patients studied one year after ileal bypass. The size of the total exchangeable cholesterol pool before operation was greater than in normals (83.0 Gm. versus 69.2 Gm.) but was reduced to nearly normal in 3 patients restudied one year after operation. The findings in this study suggest that, in addition to the observed reduction in blood cholesterol level and the increased fecal steroid excretion rate, ileal bypass results in a reduction in the exchangeable cholesterol content in other body tissues.