LACTASE DEFICIENCY IN PATIENTS WITH CYSTIC FIBROSIS

Abstract

Disaccharidase (lactase, maltase, sucrase, and palatinase) assays were performed on small intestinal mucosal biopsies obtained from 28 patients with cystic fibrosis and 90 controls. Seven patients with cystic fibrosis showed a significant reduction in lactase activity with normal values for sucrase, maltase, and palatinase. In the remaining 21 patients the enzymatic activities, expressed in units per gram of wet weight of tissue and per gram of protein, were comparable with the 90 controls. The mucosal histology showed normal villous structure. Oral tolerance tests for glucose revealed excellent absorption in all cases tested. Patients with cystic fibrosis having normal lactase activity also had good lactose absorption. However, in the patients with lactase deficiency, flat oral lactose tolerance tests were found. Five of the seven patients with lactase deficiency were able to tolerate some lactose, whereas two others were very intolerant and required elimination of lactose from their diet. This study brings out the high incidence of intestinal lactase deficiency in patients with cystic fibrosis and suggests that the lactase deficiency may be a primary genetic disorder. At present no explanation for this genetic association is available.