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LACTOSE INTOLERANCE

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Most common form of lactose malabsorption ... Molecular basis remains unknown. Developmental lactase deficiency ... Start with two Lactaid tablets with lactose ... – PowerPoint PPT presentation

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Title: LACTOSE INTOLERANCE


1
LACTOSE INTOLERANCE
  • Tova Rainis
  • Gastroenterolgy unit
  • Bnai-Zion

2
  • Common problem
  • Europe and U.S.A 7-20 - Caucasians (lowest in
    north Europe) , 80-95 Native American, 65-75
    Africans and African Americans, 50 Hispanics
  • Eastern Asia, Jewish descent gt 90

3
Lactose intake
  • Varies with age
  • Infants 35-55 of daily calories ingested
  • Lactose intake falls as weaning foods are
    introduced
  • Average adult ingests 300 gram of carbohydrates
    per day (52 starch, 37 sucrose, 5 lactose
    (mainly in milk), 3 fructose)

4
Lactose digestion and colonic salvage of
nonabsorbed lactose
5
Etiology of lactose malabsorption
  • Primary lactose malabsorption
  • Racial or ethnic lactose malabsorption
  • Developmental lactase deficiency
  • Congenital lactase deficiency
  • Secondary lactose malabsorption
  • Bacterial overgrowth/stasis
  • Mucosal injury of GIT that causes villus
    flattening

6
Racial or ethnic lactose malabsorption
  • Genetically determined reduction of lactase
    activity
  • Most common form of lactose malabsorption
  • The great majority of the worlds population
    develop low intestinal lactase during
    mid-childhood (approximately at age 5 yrs)
  • This finding is most prominent in Asian and
    African populations rare in Caucasians of
    Scandinavian background
  • Molecular basis remains unknown

7
Developmental lactase deficiency
  • Low lactase levels as a consequence of
    prematurity
  • Lactase activity in the fetus increases late in
    gestation
  • Premature infants born at 28-32 weeks of
    gestation have a reduced lactase activity

8
Congenital lactase deficiency
  • Rare autosomal recessive disorder (Finnish
    population)
  • Characterized by the absence of lactase activity
    in the small intestine, with normal histologic
    findings
  • A gene located on the same chromosome of the
    lactase gene, is responsible for CLD
  • Affected infants have diarrhea from birth,
    hypercalcemia and nephrocalcinosis

9
Secondary lactose malabsorption
  • Bacterial overgrowth or stasis syndromes
  • Increased fermentation of dietary lactose in the
    small bowel, leading to symptoms of lactose
    intolerance
  • Suspected from clinical history and from a very
    early peak of breath hydrogen during lactose
    challenge

10
Secondary lactose malabsorption - 2
  • Mucosal injury
  • Villus flattening or damage to the intestinal
    epithelium
  • Celiac disease
  • Crohns disease
  • Radiation enteritis, chemotherapy
  • HIV enteropathy
  • Whipples disease

11
Secondary lactose malabsorption -3
  • Lactase usually first affected disaccharidase in
    these disorders, because of its distal location
    on the villus
  • Treatment of the primary disorder can lead to
    restoration of lactase activity
  • Restoration of lactase activity lags behind the
    return of normal intestinal morphology

12
Clinical manifestations
  • Abdominal pain crampy, localized to
    periumbilical area, or lower quadrant
  • Bloating
  • Flatulence
  • Diarrhea
  • Vomiting
  • Stools are usually bulky, frothy and watery

13
Clinical manifestations - 2
  • Meals with higher osmolality and fat content slow
    gastric emptying and reduce the severity of
    symptoms
  • Rapid intestinal motility ? rapid movement of
    sugar are more symptomatic
  • Individuals have variable sensitivity to the
    abdominal distention produced when undigested
    lactose stimulates an influx of water into the
    lumen or to gas production

14
Differential diagnosis
  • Irritable bowel disease
  • Inflammatory bowel disease
  • Cystic fibrosis
  • Diverticulitis
  • Celiac sprue
  • Acute gastroenteritis
  • Giardiasis

15
Diagnosis
  • Test absorption (lactose absorption test) or
    malabsorption (lactose breath hydrogen test)
  • Lactose tolerance test
  • Oral administration of 50 gram lactose
  • Blood glucose levels 0, 60 and 120 min
  • Increase of blood glucose by less than 20mg/dl
    symptoms diagnostic
  • False negative diabetes, bacterial overgrowth,
    delayed gastric emptying
  • Sensitivity of 75, specificity of 96

16
Diagnosis - 2
  • Lactose breath hydrogen test
  • Oral lactose (2g/kg)
  • Breath hydrogen sampled at baseline and at 30 min
    intervals for three hours
  • Breath hydrogen value of 10ppm normal, 10-20ppm
    indeterminate unless symptomatic, gt20ppm
    diagnostic
  • False positive recent smoking, false negative
    recent use of antibiotics, lung disorders, 1
    non-hydrogen producers

17
Diagnosis -3
  • Under the age of 5 years abnormal test reflects
    an abnormal intestinal mucosa or bacterial
    overgrowth, both of which require further
    evaluation by appropriate diagnostic tests
  • Normal breath hydrogen test psychologic
    factors, intolerance to other factors in milk

18
Treatment
  • In the absence of a correctable underlying
    disease, the treatment includes four general
    principles
  • Reduced dietary lactose intake
  • Substitution of alternative nutrient sources to
    maintain energy and protein intake
  • Administration of a commercially available enzyme
    substitute
  • Maintenance of calcium intake

19
Dietary lactose restriction
  • Highest concentration in milk and ice-cream, much
    lower quantities in cheese
  • Complete restriction of lactose-containing foods
    should be necessary for a limited period to
    ascertain the specificity of the diagnosis
  • Since patients can tolerate graded increases in
    lactose intake, small quantities of lactose may
    subsequently be reintroduced into the diet, with
    careful attention to development of symptoms

20
Enzyme replacement
  • Commercially available lactase preparations
    (bacterial or yeast beta galactosidases)
  • Lactaid, Lactrase, LactAce, DairyEase and Lactrol
  • Start with two Lactaid tablets with lactose
    ingestion, and adjust both the Lactaid dose and
    the lactose load to tolerance

21
Calcium intake
  • Avoidance of milk and other dairy products can
    lead to reduced calcium intake, and increase in
    risk of osteoporosis and fracture
  • Calcium carbonate
  • Tums popular and effective
  • Infants and young children liquid calcium
    gluconate
  • Yogurt containing lactose is well tolerated by
    the patients. The yogurt contains live cultures
    of bacteria that produce lactase

22
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