Digestion and Absorption Rates of Lactose, Glucose, Galactose, and Fructose in Three Infants with Congenital Glucose‐Galactose Malabsorption

Abstract

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 < 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.