Small bowel (small intestine)
Disaccharidase (lactase) deficiency

Author: Hanni Gulwani, M.D. (see Authors page)

Revised: 12 February 2018, last major update August 2012

Copyright: (c) 2003-2018,, Inc.

PubMed Search: Disaccharidase lactase deficiency small bowel

Cite this page: Gulwani, H. Disaccharidase (lactase) deficiency. website. Accessed October 19th, 2018.
Definition / general
  • Disaccharidases are located in apical cell membrane of villous absorptive epithelial cells

Congenital deficiency:
  • Rare; malabsorption evident with milk feeding, which causes explosive, watery, frothy stools and abdominal distention

Acquired deficiency:
  • Common in North American blacks
  • Causes osmotic diarrhea
  • Acquired deficiency of lactase also occurs in duodenal mucosa of children with celiac disease (J Gastroenterol Hepatol 2008;23:e348)
  • Increased hydrogen in breath test due to bacterial fermentation of undigested lactose
  • Dietary elimination of milk and milk products