Serum bile acid response to a test meal stimulus: a sensitive test of ileal function

We assessed ileal functional integrity, as reflected in the capacity to reabsorb the bile acid, cholylglycine, by sequential measurement of postprandial serum levels of this compound. A consistent increase in cholylglycine concentration (mean +/- SEM, peak above fasting baseline = 1.86 +/- 0.14 microM) occurred in eight normal children. Five patients with ileal resection and two with primary bile acid malabsorption had a minimal postprandial increase (0.27 +/- 0.08 microM; P less than 0.005 vs controls) and excess bile acid loss in feces. Similarly, in seven patients with Crohn disease involving the ileum the postprandial increase (0.38 +/- 0.06) was less than controls (P less than 0.001). In eight patients with cystic fibrosis, the administration of pancreatic enzymes normalized the blunted response demonstrated when enzymatic therapy was interrupted suggesting an intact ileal active transport mechanism. Meal-stimulated response of serum cholylglycine concentration is a sensitive indicator of altered ileal integrity and bile acid malabsorption due to ileal resection, inflammation, or dysfunction.