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For further information see CMDT Part 17-27: Malabsorption

KEY FEATURES

  • Partial to complete lactose intolerance affects ∼50 million people in the United States

  • Occurs in 90% of Asian Americans, 70% of Black Americans, 95% of Native Americans, 50% of Mexican Americans, 60% of Jewish Americans, < 25% of White adults

  • Also occurs secondary to Crohn disease, celiac disease, viral gastroenteritis, giardiasis, short bowel syndrome, malnutrition

CLINICAL FINDINGS

  • Bloating, abdominal cramps, and flatulence with mild to moderate amounts of lactose malabsorption

  • Diarrhea

  • Differential diagnosis

    • Inflammatory bowel disease

    • Mucosal malabsorptive disorders

    • Irritable bowel syndrome

    • Pancreatic insufficiency

DIAGNOSIS

  • Diarrheal stool specimens have an increased osmotic gap and pH < 6.0

  • Hydrogen breath test: After ingestion of 50 g lactose, a rise in breath hydrogen of > 20 ppm within 90 minutes is a positive test

  • Empiric trial of a lactose-free diet for 2 weeks leads to resolution of symptoms

TREATMENT

  • Eliminate or restrict milk products

  • Spread dairy product intake throughout the day in quantities of < 12 g of lactose (1 cup of milk)

  • Use lactase enzyme supplements (eg, nonprescription formulation [Lactaid, Lactrase, Dairy Ease]) when ingesting dairy products

  • Caplets or drops of lactase may be taken with milk products

  • Patients who restrict or eliminate milk products should consider calcium supplementation (calcium citrate, 650 mg, 2 tablets orally two times daily)

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