1 Department of Pediatrics, University of Wisconsin Medical School, Madison, Wisconsin
Two patients with failure to thrive are described who excreted lactose in the urine together with the non-naturally occurring disaccharide lactulose. It was demonstrated that both sugars originated from the diet, a canned liquid modified milk product. It is suggested that the
-galactosidase activity in the gut was decreased, although blood glucose levels during a lactose tolerance test were near normal. The patients outgrew this partial enzyme defect before the age of one year.