Sections

Workup

Laboratory Studies

Lactose tolerance test

This test is rarely done in clinical practice.

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.^[22]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 the presence of diabetes and small bowel bacterial overgrowth. Abnormal gastrointestinal emptying can also affect the results of the lactose tolerance test.^[23]

The diagnosis is confirmed if the serum glucose level fails to increase by 20 g/dL above the 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.^[24]

Imaging studies

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

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.^[22]

Dietary elimination

Resolution of symptoms with the elimination of lactose-containing food products and resumption of symptoms with their reintroduction are findings suggestive of lactose intolerance.^{[25, 26]}

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 the deficiency is focal or patchy.

This is not readily available and is not usually necessary.

Treatment & Management

Vesa TH, Marteau P, Korpela R. Lactose intolerance. J Am Coll Nutr. 2000 Apr. 19(2 Suppl):165S-175S. [Medline].
Newcomer AD, McGill DB, Thomas PJ, et al. Tolerance to lactose among lactase-deficient American Indians. Gastroenterology. 1978 Jan. 74(1):44-6. [Medline].
Di Stefano M, Miceli E, Mazzocchi S, et al. Visceral hypersensitivity and intolerance symptoms in lactose malabsorption. Neurogastroenterol Motil. 2007 Nov. 19(11):887-95. [Medline].
Micic D, Rao VL, Rubin DT. Clinical approach to lactose intolerance. JAMA. 2019 Sep 26. [Medline].
Malik TF, Panuganti KK. Lactose intolerance. Stat Pearls. 2019 Jan. [Medline]. [Full Text].
Zhong Y, Priebe MG, Vonk RJ, et al. The role of colonic microbiota in lactose intolerance. Dig Dis Sci. 2004 Jan. 49(1):78-83. [Medline].
Ponte PR, de Medeiros PH, Havt A, et al. Clinical evaluation, biochemistry and genetic polymorphism analysis for the diagnosis of lactose intolerance in a population from northeastern Brazil. Clinics (Sao Paulo). 2016 Feb. 71(2):82-9. [Medline]. [Full Text].
Delacour H, Leduc A, Loucano-Perdriat A, Plantamura J, Ceppa F. Diagnosis of genetic predisposition for lactose intolerance by high resolution melting analysis. Ann Biol Clin (Paris). 2017 Feb 1. 75(1):67-74. [Medline].
Auricchio S, Rubino A, Landolt M, Semenza G, Prader A. Isolated intestinal lactase deficiency in the adult. Lancet. 1963 Aug 17. 2(7303):324-6. [Medline].
Upton J, Mackay R, George P. A simple gene test for lactose intolerance/adult hypolactasia. N Z Med J. 2007 Nov 9. 120(1265):U2817. [Medline].
Corgneau M, Scher J, Ritie-Pertusa L, et al. Recent advances on lactose intolerance: tolerance thresholds and currently available answers. Crit Rev Food Sci Nutr. 2017 Oct 13. 57(15):3344-56. [Medline].
Xiong L, Wang Y, Gong X, Chen M. Prevalence of lactose intolerance in patients with diarrhea-predominant irritable bowel syndrome: data from a tertiary center in southern China. J Health Popul Nutr. 2017 Nov 21. 36(1):38. [Medline]. [Full Text].
Harvey L, Ludwig T, Hou AQ, et al. Prevalence, cause and diagnosis of lactose intolerance in children aged 1-5 years: a systematic review of 1995-2015 literature. Asia Pac J Clin Nutr. 2018. 27(1):29-46. [Medline]. [Full Text].
Kern F Jr, Struthers JE Jr. Intestinal lactase deficiency and lactose intolerance in adults. JAMA. 1966 Mar 14. 195(11):927-30. [Medline].
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].
Di Stefano M, Veneto G, Malservisi S, et al. Lactose malabsorption and intolerance and peak bone mass. Gastroenterology. 2002 Jun. 122(7):1793-9. [Medline].
Alharbi O, El-Sohemy A. Lactose intolerance (LCT-13910C>T) genotype is associated with plasma 25-hydroxyvitamin D concentrations in caucasians: a Mendelian randomization study. J Nutr. 2017 Jun. 147(6):1063-9. [Medline].
Bayless TM, Rothfeld B, Massa C, et al. Lactose and milk intolerance: clinical implications. N Engl J Med. 1975 May 29. 292(22):1156-9. [Medline].
Deng Y, Misselwitz B, Dai N, Fox M. Lactose intolerance in adults: biological mechanism and dietary management. Nutrients. 2015 Sep 18. 7(9):8020-35. [Medline]. [Full Text].
Mishkin S. Dairy sensitivity, lactose malabsorption, and elimination diets in inflammatory bowel disease. Am J Clin Nutr. 1997 Feb. 65(2):564-7. [Medline].
Portincasa P, Bonfrate L, de Bari O, Lembo A, Ballou S. Irritable bowel syndrome and diet. Gastroenterol Rep (Oxf). 2017 Feb. 5(1):11-9. [Medline]. [Full Text].
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. 2008 Apr. 27(8):659-65. [Medline].
Hermans MM, Brummer RJ, Ruijgers AM, et al. The relationship between lactose tolerance test results and symptoms of lactose intolerance. Am J Gastroenterol. 1997 Jun. 92(6):981-4. [Medline].
Arola H. Diagnosis of hypolactasia and lactose malabsorption. Scand J Gastroenterol Suppl. 1994. 202:26-35. [Medline].
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. 1998 Dec. 17(6):631-6. [Medline].
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. 1995 Jul 6. 333(1):1-4. [Medline].
Patel YT, Minocha A. Lactose intolerance: diagnosis and management. Compr Ther. 2000 Winter. 26(4):246-50. [Medline].
Suarez FL, Savaiano DA, Levitt MD. Review article: the treatment of lactose intolerance. Aliment Pharmacol Ther. 1995 Dec. 9(6):589-97. [Medline].
Sethi S, Tyagi SK, Anurag RK. Plant-based milk alternatives an emerging segment of functional beverages: a review. J Food Sci Technol. 2016 Sep. 53(9):3408-23. [Medline]. [Full Text].
Paul AA, Kumar S, Kumar V, Sharma R. Milk analog: plant based alternatives to conventional milk, production, potential and health concerns. Crit Rev Food Sci Nutr. 2019 Oct 16. 1-19. [Medline].
Pakdaman MN, Udani JK, Molina JP, Shahani M. The effects of the DDS-1 strain of lactobacillus on symptomatic relief for lactose intolerance - a randomized, double-blind, placebo-controlled, crossover clinical trial. Nutr J. 2016 May 20. 15(1):56. [Medline]. [Full Text].
Shi LH, Balakrishnan K, Thiagarajah K, Mohd Ismail NI, Yin OS. Beneficial properties of probiotics. Trop Life Sci Res. 2016 Aug. 27(2):73-90. [Medline]. [Full Text].
Vonk RJ, Priebe MG, Koetse HA, et al. Lactose intolerance: analysis of underlying factors. Eur J Clin Invest. 2003 Jan. 33(1):70-5. [Medline].
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. 1997 May. 65(5):1502-6. [Medline].
Jarvinen RM, Loukaskorpi M, Uusitupa MI. Tolerance of symptomatic lactose malabsorbers to lactose in milk chocolate. Eur J Clin Nutr. 2003 May. 57(5):701-5. [Medline].
Beja-Pereira A, Luikart G, England PR, et al. Gene-culture coevolution between cattle milk protein genes and human lactase genes. Nat Genet. 2003 Dec. 35(4):311-3. [Medline].
Born P, Sekatcheva M, Rosch T, et al. Carbohydrate malabsorption in clinical routine: a prospective observational study. Hepatogastroenterology. 2006 Sep-Oct. 53(71):673-7. [Medline].
Hammer HF, Hammer J. Diarrhea caused by carbohydrate malabsorption. Gastroenterol Clin North Am. 2012 Sep. 41(3):611-27. [Medline].
Lomer MC, Parkes GC, Sanderson JD. Review article: lactose intolerance in clinical practice--myths and realities. Aliment Pharmacol Ther. 2008 Jan 15. 27(2):93-103. [Medline].
Mattar R, de Campos Mazo DF, Carrilho FJ. Lactose intolerance: diagnosis, genetic, and clinical factors. Clin Exp Gastroenterol. 2012. 5:113-21. [Medline]. [Full Text].
Bayless TM, Brown E, Paige DM. Lactase non-persistence and lactose intolerance. Curr Gastroenterol Rep. 2017 May. 19(5):23. [Medline].
Szilagyi A, Galiatsatos P, Xue X. Systematic review and meta-analysis of lactose digestion, its impact on intolerance and nutritional effects of dairy food restriction in inflammatory bowel diseases. Nutr J. 2016 Jul 13. 15(1):67. [Medline]. [Full Text].
Szilagyi A. Adult lactose digestion status and effects on disease. Can J Gastroenterol Hepatol. 2015 Apr. 29(3):149-56. [Medline]. [Full Text].

Media Gallery

of 0

Author

Praveen K Roy, MD, AGAF Clinical Assistant Professor of Medicine, University of New Mexico School of Medicine

Praveen K Roy, MD, AGAF is a member of the following medical societies: American Gastroenterological Association, American Society for Gastrointestinal Endoscopy

Disclosure: Nothing to disclose.

Coauthor(s)

Sarah D Komanapalli, MBBS Resident Physician in Internal Medicine, Marshfield Clinic

Sarah D Komanapalli, MBBS is a member of the following medical societies: American College of Physicians

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 College of Gastroenterology, American Gastroenterological Association, American Society for Gastrointestinal Endoscopy

Disclosure: Nothing to disclose.

Showkat Bashir, MD Assistant Professor, Department of Medicine, Division of Gastroenterology, George Washington University, Washington, DC

Showkat Bashir, MD is a member of the following medical societies: American College of Gastroenterology, American College of Physicians, American Gastroenterological Association, American Medical Association

Disclosure: Nothing to disclose.

Specialty Editor Board

Francisco Talavera, PharmD, PhD Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy; Editor-in-Chief, Medscape Drug Reference

Disclosure: Received salary from Medscape for employment. for: Medscape.

BS Anand, MD Professor, Department of Internal Medicine, Division of Gastroenterology, Baylor College of Medicine

BS Anand, MD is a member of the following medical societies: American Association for the Study of Liver Diseases, American College of Gastroenterology, American Gastroenterological Association, American Society for Gastrointestinal Endoscopy

Disclosure: Nothing to disclose.

Chief Editor

Burt Cagir, MD, FACS Clinical Professor of Surgery, Geisinger Commonwealth School of Medicine; Director, General Surgery Residency Program, Guthrie Robert Packer Hospital; Attending Surgeon, Guthrie Robert Packer Hospital and Corning Hospital

Burt Cagir, MD, FACS is a member of the following medical societies: American College of Surgeons, Association of Program Directors in Surgery, Society for Surgery of the Alimentary Tract

Disclosure: Nothing to disclose.

Additional Contributors

Ronnie Fass, MD, FACP, FACG Chief of Gastroenterology, Head of Neuroenteric Clinical Research Group, Southern Arizona Veterans Affairs Health Care System; Professor of Medicine, Division of Gastroenterology, University of Arizona School of Medicine

Ronnie Fass, MD, FACP, FACG 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 Neurogastroenterology and Motility Society, American Society for Gastrointestinal Endoscopy, Israeli Medical Association

Disclosure: Received grant/research funds from Takeda Pharmaceuticals for conducting research; Received consulting fee from Takeda Pharmaceuticals for consulting; Received honoraria from Takeda Pharmaceuticals for speaking and teaching; Received consulting fee from Vecta for consulting; Received consulting fee from XenoPort for consulting; Received honoraria from Eisai for speaking and teaching; Received grant/research funds from Wyeth Pharmaceuticals for conducting research; Received grant/research funds f.

Douglas M Heuman, MD, FACP, FACG, AGAF Chief of Hepatology, Hunter Holmes McGuire Department of Veterans Affairs Medical Center; Professor, Department of Internal Medicine, Division of Gastroenterology, Virginia Commonwealth University School of Medicine

Douglas M Heuman, MD, FACP, FACG, AGAF is a member of the following medical societies: American Association for the Study of Liver Diseases, American College of Physicians, American Gastroenterological Association

Disclosure: Received grant/research funds from Novartis for other; Received grant/research funds from Bayer for other; Received grant/research funds from Otsuka for none; Received grant/research funds from Bristol Myers Squibb for other; Received none from Scynexis for none; Received grant/research funds from Salix for other; Received grant/research funds from MannKind for other.

Abhishek Choudhary, MD Resident Physician, Department of Internal Medicine, University Hospital of Missouri-Columbia

Abhishek Choudhary, MD is a member of the following medical societies: American College of Physicians

Disclosure: Nothing to disclose.

Lactose Intolerance Workup

Laboratory Studies

Lactose tolerance test

Milk tolerance test

Other Tests

Imaging studies

Breath hydrogen test

Dietary elimination

Procedures

Small bowel biopsy

About

Membership

Apps

WebMD Network

Editions

Lactose Intolerance Workup

Laboratory Studies

Lactose tolerance test

Milk tolerance test

Other Tests

Imaging studies

Breath hydrogen test

Dietary elimination

Procedures

Small bowel biopsy

References

Tables

Contributor Information and Disclosures

What would you like to print?

Find Us On

About

Membership

Apps

WebMD Network

Editions