A noninvasive stable-isotope method to simultaneously assess pancreatic exocrine function and small bowel absorption.

OBJECTIVE

To determine if a single-step noninvasive stable isotope method of assessing digestive function could separate normal subjects from subjects with pancreatic insufficiency (maldigestion) or small bowel dysfunction (malabsorption) and to see if subjects with maldigestion could be simultaneously separated from subjects with malabsorption.

METHODS

Forty (40) normal volunteers, 18 adults with cystic fibrosis and four adults with celiac sprue, ingested a liquid test meal along with bentiromide, [13C6]PABA, and xylose (PABAX test). Serum was collected at 1 h and analyzed for PABA, [13C6]PABA, and xylose by stable isotope dilution methods using gas chromatography mass spectrometry.

RESULTS

All subjects with cystic fibrosis had abnormal pancreatic function test results, whereas three of four adults with sprue had normal values of pancreatic function. All subjects with sprue had abnormal small bowel absorption tests, whereas all adults with cystic fibrosis had apparently normal intestinal function.

CONCLUSION

The one-step, 1-h PABAX test can reliably separate normal subjects from those with either maldigestion or malabsorption and can also separate subjects with maldigestion from those with malabsorption.