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Lactose intolerance and lactase deficiency

Last reviewed: 1 Nov 2024
Last updated: 25 Sep 2024

Summary

Definition

History and exam

Key diagnostic factors

  • African-American, Native American, Asian, Hispanic, or Jewish ethnicity
  • adolescence and early adulthood
  • family history of lactase deficiency
  • enteritis/gastroenteritis
  • comorbid predisposing disease
  • history of irritable bowel syndrome diagnosis
  • symptoms after ingestion of dairy products
  • diarrhea
  • distention
  • lethargy
  • mouth ulceration
  • headache
  • poor short-term memory
  • poor concentration
  • muscle/joint pain
  • atopic dermatitis
  • faltering growth
Full details

Other diagnostic factors

  • abdominal pain/discomfort
  • borborygmi
  • flatulence
  • skin rashes
  • palpitations
  • history of asthma
  • history of peptic ulcer disease
  • history of gastroesophageal reflux disorder
  • nausea
  • vomiting
  • constipation
  • pallor
  • steatorrhea
  • weight loss
  • short stature
  • progressive disability
  • flushing
  • sensory loss
  • edema
  • hair loss
Full details

Risk factors

  • African-American, Native American, Asian, Hispanic, or Jewish ethnicity
  • adolescence and early adulthood
  • family history of lactase deficiency
  • enteritis/gastroenteritis
  • comorbid predisposing disease
  • history of irritable bowel syndrome diagnosis
Full details

Diagnostic tests

1st tests to order

  • trial of dietary lactose elimination
  • CBC
Full details

Tests to consider

  • lactose hydrogen breath test
  • stool culture
  • fecal pH
  • fecal reducing substance/sugar
  • lactose tolerance test
  • small bowel biopsy
Full details

Emerging tests

  • genotyping
  • 13C-labeled lactose breath test

Treatment algorithm

ACUTE

demonstrating symptoms of lactose intolerance

Contributors

Authors

Aasma Shaukat, MD, MPH

Director GI Outcomes Research

Robert M. and Mary H. Glickman Professor of Gastroenterology

Professor of Population Health

New York University Grossman School of Medicine

New York

NY

Disclosures

AS declares that she has no competing interests.

Acknowledgements

Dr Aasma Shaukat would like to gratefully acknowledge Dr Anton Emmanuel, Dr Mohammad Azam, and Dr Richard J. Farrell, previous contributors to this topic.

Disclosures

AE, MA, and RJF declare that they have no competing interests.

Peer reviewers

Anthony Lembo, MD

Assistant Professor of Medicine

Harvard Medical School

Beth Israel Deaconess Medical Center

Boston

MA

Disclosures

AL declares that he has no competing interests.

Michele Di Stefano, MD

Coordinator of the Gastrointestinal Motility Laboratory

University of Pavia

1st Division of Medicine

IRCCS S. Matteo Hospital Foundation

Pavia

Italy

Disclosures

MDS is the author of references cited in this topic.

  • Differentials

    • Celiac disease
    • Sucrase-isomaltase deficiency
    • Cow's milk protein intolerance
    More Differentials
  • Guidelines

    • Adverse events associated with EGD and EGD-related techniques
    • Lactose intolerance in infants, children, and adolescents
    More Guidelines
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