Comparison of three methods used in assessment of carbohydrate absorption in malnourished children.

The results of oral lactose and sucrose tolerance tests were compared with jejunal disaccharidase activities and the absorption rates of lactose and sucrose from a perfused segment of jejunum in 8 malnourished children before and after treatment. Treated children, with nearly normal utilization of circulating glucose, showed a good correlation between the oral tolerance test results and the jejunal absorption rates of lactose and sucrose. Malnourished children often showed normal rises in blood glucose despite low disaccharidase activities and poor jejunal absorption rates of glucose, lactose, and sucrose. These rises were considered to reflect poor glucose uptake by peripheral tissues rather than adequate absorption of sugars from the distal small intestine. Jejunal absorption of lactose and sucrose was only limited by the disaccharidase activities when these were very low; the rate of disaccharide absorption was usually closely related to the rate of glucose absorption, despite a wide range in disaccharidase activities.