II. Epidemiology: Incidence of Hypolactasia by ethnicity

  1. Northern european: 2 to 15%
  2. Latino patients: 50 to 80%
  3. Ashkenazi jews: 60 to 80%
  4. Black patients: 60 to 80%
  5. American Indians: 80 to 100%
  6. Asians: 95 to 100%
  7. References
    1. Sahi (1994) Scand J Gastroenterol 29(Suppl 202):7-20 [PubMed]

III. Pathophysiology

  1. Lactose deficiency is not a milk allergy
  2. Lactase enzyme present on Small Intestine brush border
    1. Lactase lyses lactose into Glucose and galactose
  3. Normal lactase physiologic changes
    1. Lactase is highest at birth
    2. Lactase levels start to decline by age 3.5 to 5 years
    3. 95% of birth lactase levels lost by early childhood
    4. Lactase continues to decrease with aging
  4. Lactase Enzyme Deficiency in the Small Intestine
    1. Lactose deficiency may be normal
    2. Europeans may be exception rather than the norm
      1. May have gene mutation that maintains lactase
  5. Lactase Deficiency results in lactose malabsorption
    1. Unabsorbed lactose draws water into Small Bowel
    2. Lactose is metabolized in the colon by Bacteria
      1. Short-chain Fatty Acids
        1. Reabsorbed with water
        2. Osmotic Diarrhea if reabsorption overloaded
      2. Gas production (Carbon dioxide, Hydrogen gas)
        1. Results in Flatulence, bloating, cramping

IV. Causes

  1. Idiopathic (most common)
    1. See Incidence per ethnicity above
    2. Physiologic waning of lactase activity in childhood
  2. Small Bowel secondary causes
    1. HIV Enteropathy
    2. Crohn's Disease
    3. Celiac Sprue
    4. Whiple's Disease
    5. Severe Viral Gastroenteritis
    6. Giardiasis
  3. Iatrogenic secondary causes
    1. Chemotherapy
    2. Radiation enteritis
    3. Oral antibiotics (Clostridium difficile overgrowth)
  4. Miscellaneous secondary causes
    1. Carcinoid Syndrome
    2. Cystic Fibrosis
    3. Gastropathy of Diabetes Mellitus
    4. Kwashiorkor
    5. Zollinger-Ellison Syndrome
    6. Alcoholism

V. Symptoms with milk product ingestion

  1. Moderate dairy intake (e.g. 8-12 ounces milk)
    1. Bloating
    2. Flatulence or gas
    3. Cramping Abdominal Pain
    4. Foul smelling stools
  2. Large dairy intake or severe intolerance
    1. More significant symptoms of those listed above
    2. Osmotic Diarrhea

VI. Signs

  1. No weight loss associated with malabsorption

VIII. Evaluation

  1. Consider empiric trial off dairy products
    1. Also Consider Elimination Diet
  2. Lactose Breath Hydrogen Test
  3. Lactose Tolerance Test (replaced by hydrogen test)

IX. Management

  1. See Lactose-Free Diet
    1. Do not completely eliminate dairy products
    2. Risk of Vitamin Deficiency
  2. Lactase enzyme replacement (e.g. Lactaid, Dairy Ease)

X. References

  1. Melrad in Goldman (2000) Cecil Medicine, p. 719
  2. Swagerty (2002) Am Fam Physician 65(9):1845-50 [PubMed]

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Related Studies

Ontology: Lactose Intolerance (C0022951)

Definition (MEDLINEPLUS)

Lactose intolerance means that you cannot digest foods with lactose in them. Lactose is the sugar found in milk and foods made with milk. After eating foods with lactose in them, you may feel sick to your stomach. You may also have

  • Gas
  • Diarrhea
  • Swelling in your stomach

Your doctor may do a blood, breath or stool test to find out if your problems are due to lactose intolerance.

Lactose intolerance is not serious. Eating less food with lactose, or using pills or drops to help you digest lactose usually helps. You may need to take a calcium supplement if you don't get enough of it from your diet, since milk and foods made with milk are the most common source of calcium for most people.

NIH: National Institute of Diabetes and Digestive and Kidney Diseases

Definition (NCI_NCI-GLOSS) The inability to digest or absorb lactose, a type of sugar found in milk and other dairy products.
Definition (NCI) Inability to fully digest and absorb lactose due to limited or no lactase activity in the small intestine. Congenital intolerance is inherited following an autosomal recessive pattern but is rare. It is more often due to a gradual decline of lactase production in adulthood following the ingestion of fewer lactose-containing foods or secondary to an intestinal mucosal brush-border injury. Prevalence is highest among Asians, Native Americans and Africans. Clinical signs include abdominal cramping, bloating, flatulence and diarrhea following the dietary intake of lactose.
Definition (MSH) The condition resulting from the absence or deficiency of LACTASE in the MUCOSA cells of the GASTROINTESTINAL TRACT, and the inability to break down LACTOSE in milk for ABSORPTION. Bacterial fermentation of the unabsorbed lactose leads to symptoms that range from a mild indigestion (DYSPEPSIA) to severe DIARRHEA. Lactose intolerance may be an inborn error or acquired.
Concepts Disease or Syndrome (T047)
MSH D007787
ICD10 E73 , E73.9
SnomedCT 190757002, 267497007, 154736007, 190750000, 700094005, 267425008
English Lactose Intolerance, Intolerance, Lactose, LACTOSE INTOLERANCE, Lactose Malabsorption, Lactose intolerance, unspecified, Malabsorption, Lactose, Cows milk enteropathy, Lactose Intolerance [Disease/Finding], cow's milk enteropathy, Intolerance;lactose, milk intolerance, lactose intolerance, Milk Intolerance, Dairy product intolerance, Dairy Product Intolerance, Alactasia, Milk Sugar Intolerance, Hypolactasia, Lactose: [intolerance] or [malabsorption] (disorder), Lactose: [intolerance] or [malabsorption], Milk intolerance, Milk intolerance (disorder), Lactose intolerance, LM - Lactose malabsorption, Lactose malabsorption, Cow's milk enteropathy, Lactose intolerance (disorder), intolerance; lactose, intolerance; milk, lactose, intolerance; milk, lactose; intolerance, lactose; malabsorption, malabsorption; lactose, milk; intolerance, lactose, milk; intolerance, Intolerance or malabsorption of lactose
Portuguese INTOLERANCIA A LACTOSE, Alactasia, Intolerância à lactose, Intolerância à Lactose, Malabsorção de Lactose
Dutch alactasie, intolerantie; lactose, intolerantie; melk, lactose, intolerantie; melk, lactose; intolerantie, lactose; malabsorptie, malabsorptie; lactose, melk; intolerantie, lactose, melk; intolerantie, Lactose-intolerantie, niet gespecificeerd, lactose-intolerantie, Intolerantie, lactose-, Lactose-intolerantie, Lactosemalabsorptie
French Alactasie, INTOLERANCE AU LACTOSE, Intolérance au lactose, Malabsorption du lactose
German Laktasemangel, LAKTOSEUNVERTRAEGLICHKEIT, Laktoseintoleranz, nicht naeher bezeichnet, Laktoseunvertraeglichkeit, Lactoseintoleranz, Laktoseintoleranz, Laktosemalabsorption
Italian Alactasia, Malassorbimento del lattosio, Intolleranza al lattosio
Spanish Alactasia, LACTOSA, INTOLERANCIA, enteropatía por leche de vaca, hipoabsorción de lactosa, intolerancia a la lactosa (trastorno), intolerancia a la lactosa, malabsorción de lactosa, Intolerancia a la lactosa, Intolerancia a la Lactosa, Malabsorción de Lactosa
Japanese 乳糖分解酵素欠損, ラクトース不耐性, ラクトースフタイセイ, ニュウトウブンカイコウソケッソン, 乳糖不耐症, ラクトース不耐症, 乳糖不耐性
Swedish Laktosintolerans
Czech laktosa - nesnášenlivost, Intolerance laktózy, Alaktázie
Finnish Laktoosi-intoleranssi
Korean 유당불내증, 상세불명의 유당불내증
Polish Nietolerancja laktozy
Hungarian Lactose intolerantia, Alactasia
Norwegian Laktoseintoleranse, Melkesukkerintoleranse