Diagnosis of congenital glucose-galactose malabsorption by measuring sugar- and amino acid-evoked potential differences in jejunum in vivo.

A girl who was clinically suspected of having congenital glucose-galactose malabsorption was investigated for sugar- and amino acid-evoked potential differences in the jejunum in vivo using a jejunal perfusion technique. She was fed an ordinary diet without suffering diarrhea at the time (at age 2) of this study. Her nutritional condition and development were normal. The disaccharidase activities of a biopsy specimen of the jejunal mucosa, which were assayed at 1 year of age when she was not having diarrhea, were normal. Jejunal perfusion of 100-mM solutions of D-glucose or D-maltose evoked no significant change in the electrical potential difference. On the other hand, 100 mM of L-glycine or L-leucine solution evoked a normal increase of the lumen negative potential difference (4.4 mV and 3.6 mV, respectively). Therefore, the patient was diagnosed as having congenital glucose-galactose malabsorption due to a defect of Na-dependent glucose-galactose active transport. These findings indicate that the measurement of sugar- and amino acid-evoked potential differences is a simple and reliable method for the diagnosis of congenital glucose-galactose malabsorption.