Lactose intolerance is characterized by reduced lactase concentration in the mucosal brush border of the small intestine (also known as hypolactasia).
It exists in four distinct forms: primary, secondary, congenital, and developmental.
Symptoms can be gastrointestinal and/or systemic.
Dietary elimination and challenge are generally diagnostic.
Treatment includes reduction or elimination of dietary lactose.
If elimination of lactose is necessary, alternative calcium sources are recommended.
Lactose intolerance refers to the development of gastrointestinal and/or systemic symptoms secondary to malabsorption of lactose caused by hypolactasia. It is characterized by reduced lactase (lactase-phlorizin hydrolase enzyme) concentration in the mucosal brush border (microvilli) of the small intestine, usually at the age of weaning.
[1]
Matthews SB, Waud JP, Roberts AG, et al. Systemic lactose intolerance: a new perspective on an old problem. Postgrad Med J. 2005 Mar;81(953):167-73.
https://pmj.bmj.com/content/81/953/167.long
http://www.ncbi.nlm.nih.gov/pubmed/15749792?tool=bestpractice.com
[2]
Heyman MB; American Academy of Pediatrics, Committee on Nutrition. Lactose intolerance in infants, children, and adolescents. Pediatrics. 2006 Sep;118(3):1279-86.
http://pediatrics.aappublications.org/content/118/3/1279.long
http://www.ncbi.nlm.nih.gov/pubmed/16951027?tool=bestpractice.com
[3]
Lomer ME, Parkes GC, Sanderson JD. Lactose intolerance in clinical practice - myths and realities. Aliment Pharmacol Ther. 2008 Jan 15;27(2):93-103.
http://www.ncbi.nlm.nih.gov/pubmed/17956597?tool=bestpractice.com
Malabsorption of lactose, however, does not always manifest as gastrointestinal symptoms; development of symptoms and symptom severity depend on the amount and rate of lactose reaching the colon, as well as the type and amount of colonic flora.
[1]
Matthews SB, Waud JP, Roberts AG, et al. Systemic lactose intolerance: a new perspective on an old problem. Postgrad Med J. 2005 Mar;81(953):167-73.
https://pmj.bmj.com/content/81/953/167.long
http://www.ncbi.nlm.nih.gov/pubmed/15749792?tool=bestpractice.com