Lactose intolerance
Alerts and Notices
Synopsis
Lactase deficiency can be primary, secondary, or congenital.
- Primary – Low levels of lactase enzyme. Symptom onset may be in childhood or adulthood.
- Secondary – Reversible lactase deficiency caused by mucosal injury, often in the setting of viral illnesses.
- Congenital – A rare autosomal recessive absence of lactase activity at birth leading to diarrhea and hypercalcemia in infancy, predisposing patients to nephrocalcinosis.
For more information on congenital lactase deficiency, see OMIM.
Codes
ICD10CM:E73.9 – Lactose intolerance, unspecified
SNOMEDCT:
267425008 – Lactose Intolerance
Look For
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Diagnostic Pearls
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Differential Diagnosis & Pitfalls
- Infectious gastroenteritis (bacterial, viral, helminth)
- Congenital lactase deficiency
- Celiac disease
- Small intestinal bacterial overgrowth
- Inflammatory bowel disease (ulcerative colitis, Crohn disease)
- Irritable bowel syndrome
- Anxiety disorders
- Biliary colic
- Chronic mesenteric ischemia
- Chronic pancreatitis
- Collagenous gastritis
- Collagenous colitis
- Lymphocytic colitis
- Colon cancer
- Food allergies
- Malignancy: gastric, small bowel, or large bowel
- Pancreatic cancer
- Postcholecystectomy syndrome
- Bile acid diarrhea
- Somatostatinomas
- Laxative abuse
- Cow milk allergy
Best Tests
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Management Pearls
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Therapy
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References
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Last Reviewed:01/11/2018
Last Updated:03/04/2020
Last Updated:03/04/2020