eMedicine Specialties > Gastroenterology > Intestine

Lactose Intolerance: Differential Diagnoses & Workup

Author: Praveen K Roy, MD, Comments and Criticisms Editor, Cochrane Colorectal Cancer Group
Coauthor(s): Abhishek Choudhary, MD, Resident, Department of Internal Medicine, University Hospital of Missouri; Mohamed Othman, MD, Staff Physician, Department of Internal Medicine, University of New Mexico School of Medicine; Homayoun Shojamanesh, MD, Former Fellow, Digestive Diseases Branch, National Institutes of Health; Jack Bragg, DO, FACOI, Assistant Professor, Department of Clinical Medicine, University of Missouri School of Medicine; Gautam Dehadrai, MD, Department Chair, Section Chief, Department of Interventional Radiology, Norman Regional Hospital
Contributor Information and Disclosures

Updated: Aug 12, 2008

Differential Diagnoses

Gastrinoma
Giardiasis
Inflammatory Bowel Disease
Irritable Bowel Syndrome

Other Problems to Be Considered

Sucrase deficiency
Diabetic diarrhea
Other disorders listed under causes of secondary lactose intolerance

Workup

Laboratory Studies

  • Lactose tolerance test
    • Measure serial blood glucose levels after an oral lactose load. A fasting serum glucose level is obtained, after which 50 g of lactose is administered. Measure the serum glucose level at 0, 60, and 120 minutes.
    • The lactose tolerance test has a sensitivity of 75% and a specificity of 96%.
    • False-negative results occur in presence of diabetes and small bowel bacterial overgrowth. Abnormal gastrointestinal emptying can also affect the results of the lactose tolerance test.
    • The diagnosis is confirmed if the serum glucose level fails to increase by 20 g/dL above baseline.
  • Milk tolerance test
    • Administer 500 mL of milk and measure the blood glucose level.
    • An increase of less than 9 mg/dL indicates lactose malabsorption.

Imaging Studies

  • Imaging tests are not helpful in the diagnosis of primary lactose intolerance, but they may be helpful for excluding secondary causes.

Other Tests

  • Breath hydrogen test
    • This is the diagnostic test of choice.
    • Subjects are administered lactose after an overnight fast, after which expired air samples are collected before and at 30-minute intervals for 3 hours to assess hydrogen gas concentrations.
    • A rise in breath hydrogen concentration greater than 20 parts per million over the baseline after lactose ingestion suggests lactase deficiency.
  • Dietary elimination: Resolution of symptoms with elimination of lactose-containing food products and resumption of symptoms with the reintroduction are findings suggestive of lactose intolerance.

Procedures

  • Small bowel biopsy
    • This is the criterion standard; however, it is invasive and rarely performed. A major advantage is that it provides definitive information.
    • Biopsy samples from the small bowel are assayed for lactase activity. The biopsy results may be normal if deficiency is focal or patchy.
    • This is not readily available and is not usually necessary.

More on Lactose Intolerance

Overview: Lactose Intolerance
Differential Diagnoses & Workup: Lactose Intolerance
Treatment & Medication: Lactose Intolerance
Follow-up: Lactose Intolerance
References
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References

  1. Arola H. Diagnosis of hypolactasia and lactose malabsorption. Scand J Gastroenterol Suppl. 1994;202:26-35. [Medline].

  2. Auricchio S, Rubino A, Landholt M. Isolated lactase deficiency in the adult. Lancet. 1963;2:324-6.

  3. Bayless TM, Rothfeld B, Massa C, et al. Lactose and milk intolerance: clinical implications. N Engl J Med. May 29 1975;292(22):1156-9. [Medline].

  4. Beja-Pereira A, Luikart G, England PR, et al. Gene-culture coevolution between cattle milk protein genes and human lactase genes. Nat Genet. Dec 2003;35(4):311-3. [Medline].

  5. Beyerlein L, Pohl D, Delco F, et al. Correlation between symptoms developed after the oral ingestion of 50 g lactose and results of hydrogen breath testing for lactose intolerance. Aliment Pharmacol Ther. Apr 2008;27(8):659-65. [Medline].

  6. Born P, Sekatcheva M, Rosch T, et al. Carbohydrate malabsorption in clinical routine: a prospective observational study. Hepatogastroenterology. Sep-Oct 2006;53(71):673-7. [Medline].

  7. Carroccio A, Montalto G, Cavera G, et al. Lactose intolerance and self-reported milk intolerance: relationship with lactose maldigestion and nutrient intake. Lactase Deficiency Study Group. J Am Coll Nutr. Dec 1998;17(6):631-6. [Medline].

  8. Di Stefano M, Miceli E, Mazzocchi S, et al. Visceral hypersensitivity and intolerance symptoms in lactose malabsorption. Neurogastroenterol Motil. Nov 2007;19(11):887-95. [Medline].

  9. Di Stefano M, Veneto G, Malservisi S, et al. Lactose malabsorption and intolerance and peak bone mass. Gastroenterology. Jun 2002;122(7):1793-9. [Medline].

  10. Hermans MM, Brummer RJ, Ruijgers AM, et al. The relationship between lactose tolerance test results and symptoms of lactose intolerance. Am J Gastroenterol. Jun 1997;92(6):981-4. [Medline].

  11. Järvinen RM, Loukaskorpi M, Uusitupa MI. Tolerance of symptomatic lactose malabsorbers to lactose in milk chocolate. Eur J Clin Nutr. May 2003;57(5):701-5. [Medline].

  12. Kern F Jr, Struthers JE Jr. Intestinal lactase deficiency and lactose intolerance in adults. JAMA. Mar 14 1966;195(11):927-30. [Medline].

  13. Kudlacek S, Freudenthaler O, Weissboeck H, et al. Lactose intolerance: a risk factor for reduced bone mineral density and vertebral fractures?. J Gastroenterol. 2002;37(12):1014-9. [Medline].

  14. Lomer MC, Parkes GC, Sanderson JD. Review article: lactose intolerance in clinical practice--myths and realities. Aliment Pharmacol Ther. Jan 15 2008;27(2):93-103. [Medline].

  15. Mishkin S. Dairy sensitivity, lactose malabsorption, and elimination diets in inflammatory bowel disease. Am J Clin Nutr. Feb 1997;65(2):564-7. [Medline].

  16. Newcomer AD, McGill DB, Thomas PJ, et al. Tolerance to lactose among lactase-deficient American Indians. Gastroenterology. Jan 1978;74(1):44-6. [Medline].

  17. Patel YT, Minocha A. Lactose intolerance: diagnosis and management. Compr Ther. Winter 2000;26(4):246-50. [Medline].

  18. Suarez FL, Savaiano D, Arbisi P, et al. Tolerance to the daily ingestion of two cups of milk by individuals claiming lactose intolerance. Am J Clin Nutr. May 1997;65(5):1502-6. [Medline].

  19. Suarez FL, Savaiano DA, Levitt MD. A comparison of symptoms after the consumption of milk or lactose-hydrolyzed milk by people with self-reported severe lactose intolerance. N Engl J Med. Jul 6 1995;333(1):1-4. [Medline].

  20. Suarez FL, Savaiano DA, Levitt MD. Review article: the treatment of lactose intolerance. Aliment Pharmacol Ther. Dec 1995;9(6):589-97. [Medline].

  21. Upton J, Mackay R, George P. A simple gene test for lactose intolerance/adult hypolactasia. N Z Med J. Nov 9 2007;120(1265):U2817. [Medline].

  22. Vesa TH, Marteau P, Korpela R. Lactose intolerance. J Am Coll Nutr. Apr 2000;19(2 Suppl):165S-175S. [Medline].

  23. Vonk RJ, Priebe MG, Koetse HA, et al. Lactose intolerance: analysis of underlying factors. Eur J Clin Invest. Jan 2003;33(1):70-5. [Medline].

  24. Zhong Y, Priebe MG, Vonk RJ, et al. The role of colonic microbiota in lactose intolerance. Dig Dis Sci. Jan 2004;49(1):78-83. [Medline].

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Further Reading

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Keywords

lactose intolerance, lactose intolerant, milk, milk allergy, lactase, lactose allergy, lactase deficiency, milk products, dairy allergy, dairy allergies, dairy products, food allergy, food allergies, lactose malabsorption, lactose maldigestion, lactose deficient, lactose tolerance test, milk tolerance test, glucose, galactose, hypolactasia, osteopenia, osteoporosis, disaccharidase deficiency

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Contributor Information and Disclosures

Author

Praveen K Roy, MD, Comments and Criticisms Editor, Cochrane Colorectal Cancer Group
Praveen K Roy, MD is a member of the following medical societies: American College of Gastroenterology, American Gastroenterological Association, and Canadian Association of Gastroenterology
Disclosure: Nothing to disclose.

Coauthor(s)

Abhishek Choudhary, MD, Resident, Department of Internal Medicine, University Hospital of Missouri
Abhishek Choudhary, MD is a member of the following medical societies: American College of Physicians
Disclosure: Nothing to disclose.

Mohamed Othman, MD, Staff Physician, Department of Internal Medicine, University of New Mexico School of Medicine
Disclosure: Nothing to disclose.

Homayoun Shojamanesh, MD, Former Fellow, Digestive Diseases Branch, National Institutes of Health
Homayoun Shojamanesh, MD is a member of the following medical societies: American Gastroenterological Association, American Medical Association, and American Society for Gastrointestinal Endoscopy
Disclosure: Nothing to disclose.

Jack Bragg, DO, FACOI, Assistant Professor, Department of Clinical Medicine, University of Missouri School of Medicine
Jack Bragg, DO, FACOI is a member of the following medical societies: American College of Osteopathic Internists and American Osteopathic Association
Disclosure: Nothing to disclose.

Gautam Dehadrai, MD, Department Chair, Section Chief, Department of Interventional Radiology, Norman Regional Hospital
Gautam Dehadrai, MD is a member of the following medical societies: American College of Radiology, Medical Council of India, and Radiological Society of North America
Disclosure: Nothing to disclose.

Medical Editor

Ronnie Fass, MD, Director of GI Motility Laboratory, Tucson VA Medical Center, Associate Professor, Department of Internal Medicine, Division of Gastroenterology, University of Arizona School of Medicine
Ronnie Fass, MD is a member of the following medical societies: American College of Gastroenterology, American College of Physicians-American Society of Internal Medicine, American Gastroenterological Association, American Motility Society, American Society for Gastrointestinal Endoscopy, and Israel Medical Association
Disclosure: Nothing to disclose.

Pharmacy Editor

Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine
Disclosure: Nothing to disclose.

Managing Editor

Douglas M Heuman, MD, FACP, Director of Hepatology, McGuire Veterans Affairs Medical Center, Professor, Department of Internal Medicine, Division of Gastroenterology, Virginia Commonwealth University School of Medicine
Douglas M Heuman, MD, FACP is a member of the following medical societies: American Association for the Study of Liver Diseases, American College of Physicians, and American Gastroenterological Association
Disclosure: Nothing to disclose.

CME Editor

Alex J Mechaber, MD, FACP, Assistant Dean for Medical Curriculum, Associate Professor of Medicine, Division of General Internal Medicine, University of Miami Miller School of Medicine
Alex J Mechaber, MD, FACP is a member of the following medical societies: Alpha Omega Alpha, American College of Physicians-American Society of Internal Medicine, and Society of General Internal Medicine
Disclosure: Nothing to disclose.

Chief Editor

Julian Katz, MD, Clinical Professor of Medicine, Drexel University College of Medicine; Consulting Staff, Department of Medicine, Section of Gastroenterology and Hepatology, Hospital of the Medical College of Pennsylvania
Julian Katz, MD is a member of the following medical societies: American College of Gastroenterology, American College of Physicians, American Gastroenterological Association, American Geriatrics Society, American Medical Association, American Society for Gastrointestinal Endoscopy, American Society of Law Medicine and Ethics, American Trauma Society, Association of American Medical Colleges, and Physicians for Social Responsibility
Disclosure: Nothing to disclose.

 
 
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