EVALUATION OF DIFFERENTIAL DISACCHARIDE EXCRETION IN URINE FOR NONINVASIVE INVESTIGATION OF ALTERED INTESTINAL DISACCHARIDASE ACTIVITY CAUSED BY ALPHA-GLUCOSIDASE INHIBITION, PRIMARY HYPOLACTASIA, AND CELIAC-DISEASE

Background/Aim-The reliability of a quantitative method for the non-in vasive assessment of intestinal disaccharide hydrolysis was assessed. Methods-Differential excretion of intact disaccharide, expressed as ra tios of lactulose to appropriate hydrolysable disaccharides in urine c ollected following combined ingestion, has been investigated in health y volunteers with drug induced alpha-glucosidase inhibition, in subjec ts with primary hypolactasia, and patients with coeliac disease. Resul ts-Oral administration of the alpha-glucosidase inhibitor 'Acarbose' ( BAY g 5421, 200 mg) together with sucrose and lactulose increased the urinary sucrose/lactulose excretion ratios (% dose/10 h) fivefold. The effect was quantitatively reproducible, a higher dose of 'Acarbose' ( 500 mg) increasing the excretion ratio to about 1.0 indicating complet e inhibition of intestinal sucrase activity. The suitability of the me thod for measuring differences in dose/response and duration of action was assessed by comparing three different alpha-glucosidase inhibitor s (BAY g 5421, BAY m 1099, and BAY o 1248) and found to be satisfactor y. Subjects with primary adult hypolactasia had urine lactose/lactulos e excretion ratios raised to values indicating reduced rather than com plete absence of lactase activity whereas sucrose/lactulose ratios wer e not significantly affected. 'Whole' intestinal disaccharidase activi ty assessed by this method demonstrated impairment of lactase, sucrase , and isomaltase in eight, one, and seven, respectively, of 20 patient s with coeliac disease. By contrast in vitro assay of jejunal biopsy t issue indicated pan-disaccharidase deficiency in all but five of these patients. This shows the importance of distinguishing between 'local' and 'whole' intestinal performance. Conclusions-Differential urinary excretion of ingested disaccharides provides a reliable, quantitative, and non-invasive technique for assessing profiles of intestinal disac charidase activity.