One-hour blood xylose in the diagnosis of cows milk protein-sensitive enteropathy.

The 1-hour xylose absorption test was evaluated as method for the diagnosis of cows' milk protein-sensitive enteropathy in a prospective study of 48 infants with diarrhoea clinically suspected to be due to intolerance of cows' milk. The infants were maintained on a lactose and cows milk protein-free diet for 6-8 weeks and then were challenged with cows' milk protein. Jejunal biopsies and the 1-hour xylose absorption test were performed immediately before and 20-24 hours after cows' milk provocation. After milk provocation, 30 infants had clinical, enzymological, and histological relapse, and in 28 of them there was a significant depression of post-provocation blood xylose levels. Six infants had histological and enzymological relapse but clinically they tolerated cows' milk. The post-provocation blood xylose level was depressed in all infants. Ten infants had enzymological relapse without histological or clinical relapse. The post-challenge blood xylose was depressed significantly (greater than 20%) in 3, mildly depressed in 3 (16-18%), and not depressed in four. Two infants clinically, histologically, and enzymologically tolerated cows' milk; in each the post-challenge xylose was depressed (22%, 12%). It appears that the 1-hour blood xylose test is not as reliable as the jejunal biopsy in the diagnosis of cows' milk protein-sensitive enteropathy.