The role of urinary indican as a predictor of bacterial colonization in the human jejunum.

To evaluate the role of urinary indican excretion and several common absorptive tests as predictors of bacterial colonization in the human jejunum, we analyzed the relationship between indican excretion and quantitative jejunal cultures, tryptophan absorption, enteric protein loss, fecal nitrogen excretion, D-xylose and lactose tolerance tests, and B12 and fat absorption in 40 subjects. Indican excretion correlated poorly with jejunal colony counts (r = 0.22). Neither tryptophan load or absorption, nor nitrogen excretion were related to indicanuria, but there was a modest correlation between enteric protein loss and urinary indican values (r = 0.54). Lactose tolerance tests and D-xylose, B12 and fat absorption showed no predictive value for identifying patients with high colony counts. Compared to quantitative small bowel culture, none of the tests studied provided suitable methods for screening for bacterial contamination of the human jejunum.