Disaccharidase activities in children: Normal values and comparison based on symptoms and histologic changes

Background: The relationship between symptoms, intestinal mucosal histology , and disaccharidase activities is not well defined. An analysis of disacch aridase activities was performed in children grouped by age, symptoms, and intestinal mucosal histology and normal values established. Methods: Disaccharidase activities and histology of 246 endoscopically obta ined duodenal biopsies in 232 patients (121 girls; age range, 0.08-17 years ; mean, 5.9 years) in a 3-year period were reviewed. Patients were divided into two groups based on absence (group 1; n = 142) or presence (group 2; n = 90) of diarrhea and were subdivided by age into, less than 24 months of age and 24 months of age or more. Histologic changes within groups were cla ssified as (A) normal, (B) mild, or (C) moderate to severe based on villus height abnormalities. A questionnaire was sent to 34 patients with hypolact asia to assess the efficacy of lactose avoidance and/or lactase supplementa tion. Results: All group I patients had normal findings in analysis of mucosal sp ecimens, and their disaccharidase activities showed normal values because t hey had no diarrhea. The geometric means (95% confidence interval) in child ren aged less than 24 months are (in micromoles of substrate hydrolyzed per minute at 37 degrees C per gram protein) (units [U]) lactase, 36.7 (13.3-1 00.4); maltase, 178.5 (88.9-356.3); palatinase, 12.7 (3.8-41.5); and sucras e 60.0 (24.0-148.1). In children 24 months of age or more, the values are 2 3.2 (3.9-108.1), 167.6 (78.8-355.9), 12.7 (4.9-32.9), and 51.0 (20.5-126.0) , respectively. Only lactase activity decreased with age (p < 0.05). No dif ferences in disaccharidase activities were noted in patients with and witho ut diarrhea if the mucosal histology was normal (group 1A vs. 2A). In patie nts with diarrhea, values were commensurate with the degree of mucosal inju ry, especially in the older group. Twenty-two of 27 patients (81%) who resp onded to the questionnaire had benefited from lactase supplementation and/o r lactose avoidance. Conclusions: We have established normal values for disaccharidase activitie s in the pediatric population. Although the disaccharidase activities corre late more with degree of intestinal mucosal injury than with symptoms, thei r activities are difficult to predict accurately based on these criteria. I f required, disaccharidase activities should be measured biochemically.