Disaccharidases and Histology of Duodenal Mucosa in Congenital Lactose Malabsorption

Summary A study has been made of the disaccharidase activities and histology of duodenal mucosa in two infants with typical congenital lactose malabsorption. The mucosal samples were taken by means of peroral intestinal biopsy. At the time Of biopsy, the patients were 2½ and 4½ months old and they had been on lactose free diet 39 days and 3 ½ months respectively. Both patients demonstrated a typical clinical picture of lactose and cellobiose malabsorption. In the mucosal samples, lactase and cellobiase activities were almost absent in both patients, whereas other disaccharidase activities were within the normal range. The histological picture of the mucosa was normal in one patient, and slight, partial villous atrophy was seen in the other. This study confirms that the cause of congenital lactose malabsorbtion is an enzyme defect of the intestinal mucosa which histologically may appear normal.