Digestion and absorption rates of lactose, glucose, galactose, and fructose in three infants with congenital glucose-galactose malabsorption: perfusion studies.

The digestion rates of lactose and the absorption rates of glucose, galactose, and fructose were studied by continuous perfusion of the jejunum in three patients aged 7 weeks to 9 months with congenital glucose-galactose malabsorption (infusion rate:1.0 ml min-1; concentration of each sugar: 200 mM; perfusion distance: 30 cm). The mean absorption rates of glucose and galactose were 26.5 and 43.8 mumol min-1 30 cm-1, respectively, and were significantly reduced (p less than 0.001) to 13 and 22%, respectively, of intake. On the other hand, the absorption of fructose was 133.3 mumol min-1 30 cm-1, i.e., as high as in the controls. The hydrolysis rate of lactose was also normal (134.0 mumol min-1 30 cm-1). However, the absorption rates of glucose and galactose released from the disaccharide were as low as the perfusion of free monosaccharides. In patients with glucose-galactose malabsorption the glucose absorption rate is as low as that of galactose. No additional glucose transport system seems to exist. A hydrolase related transport system is also of no importance in compensating for the primary defect of monosaccharide absorption.