Lactose Intolerance
Lactose Intolerance: Excerpt from The 5-Minute Pediatric Consult
Vera De Matos, MDDror Wasserman, MD (4th Edition)
Lactose Intolerance - BASICS
Lactose Intolerance - description
- Lactose is a disaccharide built from glucose and galactose and is the major carbohydrate in infant’s food (breast milk or milk-based formula).
- Lactose is important as a source of energy; it promotes the absorption of calcium, phosphorus, and iron and has a probiotic effect on the gut flora.
- Lactose intolerance is defined as the inability to digest the disaccharide lactose secondary to deficiency of the enzyme lactase, resulting in clinical symptoms.
- 4 types of lactase deficiency:
- Congenital lactase deficiency:
- Extremely rare
- Presents during the newborn period, often with the 1st feeding of lactose-containing formula
- Will cause severe diarrhea and failure to thrive and risk the newborn’s life
- Primary lactase deficiency or adult-type hypolactasia is due to relative or absolute absence of lactase:
- Develops during childhood at different ages in different racial groups
- Most common cause of lactose intolerance
- Secondary lactase deficiency results from small bowel injury (acute gastroenteritis, persistent diarrhea, small bowel bacterial overgrowth, chemotherapy). Can present at any age, but is more common in infancy
- Developmental lactase deficiency is the relative lactase deficiency observed in premature infants of <34 weeks’ gestation.
Lactose Intolerance - epidemiology
Lactose Intolerance - prevalence
- ~70% of the world’s population has primary lactase deficiency.
- The prevalence of primary lactase deficiency in Northern Europeans, who have a diet rich in dairy, is 2%.
- In Hispanic people, the prevalence of primary lactase deficiency is 50–80%.
- In Ashkenazi Jewish people as well as in African Americans the prevalence is 60–80%.
- In the Asian population, the prevalence of primary lactase deficiency is almost 100%.
- Nearly 20% of children <5 years from Hispanic, Asian, or African American descent have lactase deficiency and lactose malabsorption.
- Caucasian children usually do not develop symptoms until after 5 years of age.
Lactose Intolerance - risk factors
Lactose Intolerance - genetics
- Posttranslational regulatory mechanisms in primary lactase deficiency or adult–type hypolactasia
- Correlation between the genetic polymorphism of mRNA and persistence of lactase activity with early loss at 1–2 years in Thai children and late loss at 10–20 years in Finnish children
Lactose Intolerance - pathophysiology
- The symptoms depend on the amount of lactose ingested.
- Malabsorbed lactose creates an osmotic load that draws fluid and electrolytes to the bowel lumen, leading to diarrhea.
- Nonabsorbed lactose is the substrate for intestinal bacteria. In the colon, bacteria metabolize lactose, producing volatile fatty acids and gases leading to flatulence, bowel distension, pain, and low pH.
Lactose Intolerance - DIAGNOSIS
Lactose Intolerance - signs & symptoms
Lactose Intolerance - history
- Classic symptoms include bloating, gaseousness, colicky abdominal pain, and diarrhea after digestion of lactose-containing meal.
- Diet history provides important information.
- Detailed history of symptoms: Blood or mucus in the stools, failure to thrive, fat malabsorption, or any extraintestinal symptoms strongly suggest different causes.
- Symptoms vary in severity with dose of lactose ingested.
- Association with milk ingestion may not be evident.
Lactose Intolerance - physical exam
- Height and weight should be measured and plotted against age-appropriate norms; any deviation should not be attributed to lactose intolerance alone.
- Abdomen percussion: Abdomen may be distended.
- Blood in the stool must be further evaluated, because lactose intolerance does not cause bleeding.
Lactose Intolerance - tests
Lactose Intolerance - lab
- Stool-reducing substances and fecal acidity:
- A positive result indicates malabsorption of carbohydrates.
- A pH <6.0 or reducing substances >0.5% are interpreted as a positive result.
- Lactose hydrogen breath test:
- Noninvasive and highly sensitive
- The only source of hydrogen is fermented unabsorbed carbohydrates. A rise of breath HHowever, the frequently poor association between symptoms of lactose intolerance and breath HFalse-positive test results occur owing to inadequate fasting before the test, rapid intestinal transit, toothpaste, smoking, and bacterial overgrowth.
- False-negative results occur owing to diarrhea, hyperventilation, recent antibiotic exposure, and delayed gastric emptying. Up to 10% of the population are colonized with bacteria unable to produce hydrogen and will give a negative result.
- Lactase activity measurement of biopsy (invasive and expensive): Saved for patients undergoing upper endoscopy to exclude celiac disease
Lactose Intolerance - pathological findings
- Disaccharidase activity can be measured in biopsy specimens of the small bowel and compared with normal values.
- The small bowel intestinal histology will often be normal in primary lactase deficiency (unless the reason is insult/damage to the small bowel mucosa).
Lactose Intolerance - differencial diagnosis
Lactose intolerance may be secondary to a generalized small bowel mucosal dysfunction; the presence of other symptoms should prompt an evaluation. The differential diagnosis includes:
- Infection:
- Viral and bacterial infections can cause secondary lactose intolerance. Most common pathogen is rotavirus.
- Parasitic infections can mimic lactose intolerance (giardiasis).
- Inflammatory: Small intestinal Crohn disease can have associated lactose intolerance.
- Congenital:
- Other carbohydrate enzyme deficiencies can mimic lactose intolerance. This includes sucrase– isomaltase or glucose–galactose malabsorption:
- Cystic fibrosis
- Shwachman-Diamond syndrome (SDS): Primary features include:
- Bone marrow insufficiency
- Pancreatic insufficiency
- Skeletal abnormalities
- Short stature
- Allergic/Immune:
- Celiac disease often is associated with lactose intolerance due to small intestinal damage.
- Protein allergy can cause secondary lactose intolerance.
Lactose Intolerance - TREATMENT
Lactose Intolerance - general measures
- Removal of lactose from the diet is effective in eliminating symptoms. However, a milkfree diet may result in calcium deficiency.
- Predigestion of lactose can be done by the addition of commercially available enzyme supplementation. Multiple products are available over the counter. Liquid preparations, capsules, and chewable tablets can be obtained.
- Acquired deficiencies, particularly those associated with infection, may resolve over time. Most patients with lactose intolerance will not recover the ability to digest lactose.
- Supplemental probiotics may improve symptoms of lactose intolerance.
Lactose Intolerance - diet
- Lactose-free formula, lactase-containing milk
- Substitutes for cow’s milk based on rice or soy
- Yogurt and aged cheeses have a smaller content of lactose.
Lactose Intolerance - medication
- Oral lactase replacement capsules
- Calcium supplements to meet daily recommended intake levels if dairy-free diets are used
Lactose Intolerance - FOLLOW UP
Lactose Intolerance - prognosis
- Prognosis of lactase deficiency and clinical intolerance is excellent as elimination and enzyme replacement are possible; with lactose avoidance or with enzyme supplementation, the child can control and eliminate symptoms.
- However, lactose intolerance may be secondary to disease processes that should be treated promptly.
Lactose Intolerance - bibliography
- de Vrese M, Stegelmann A, Richter B, et al. Probiotics—compensation for lactase insufficiency. Am J Clin Nutr. 2001;73(2 suppl):421S–429S.
- Heyman MB. Lactose intolerance in infants, children, and adolescents. Pediatrics. 2006;118:1279–1286.
- Kerner JA Jr. Formula allergy and intolerance. Gastroenterol Clin North Am. 1995;24:1–25.
- Kokkonen J, Tikkanen S, Savilahti E. Residual intestinal disease after milk allergy in infancy. J Pediatr Gastroenterol Nutr. 2001;32:156–161.
- Murray JA. The widening spectrum of celiac disease. Am J Clin Nutr. 1999;69:354–365.
Naim HY, Zimmer KP. Genetically determined dissacharidase deficiency. In: Walker WA, Goulet OJ, eds. Pediatric Gastrointestinal Disease. Ontario: BC Decker; 2004:888–892.- Rasinpera H, Saarinen K, Pelkonen A, et al. Molecularly defined adult-type hypolactasia in school-aged children with a previous history of cow’s milk allergy. World J Gastroenterol. 2006;12(14):2264–2268.
- Suarez FL, Saviano DA, Levitt MD. A comparison of milk or lactose hydrolyzed milk by people with self-reported severe lactose intolerance. N Engl J Med. 1995;333:1–5.
- Veligati LN, Treem WR, Sullivan B, et al. Delta 10 ppm versus delta 20 ppm: A reappraisal of diagnostic criteria for breath hydrogen testing in children. Am J Gastroenterol. 1994;89:758–761.
Lactose Intolerance - CODES
Lactose Intolerance - icd9
271.3 Lactose intolerance
Lactose Intolerance - FAQ
- Q: When is the usual time for presentation of lactose intolerance?
- A: In whites, the age of presentation is after 5 years of age. In blacks, 2–3-year-old children may present with clinical signs and symptoms. The differential diagnosis must distinguish primary from secondary causes.
- Q: Does lactose intolerance prevent the child from ever eating lactose?
- A: No, the patient can take smaller amounts of lactose in the diet or have the enzyme supplemented.
- Q: Does this problem ever get better?
- A: No, it is a lifelong problem, but seems to become less symptomatic for adults, in light of their individual desire to tolerate symptoms.
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Book Source Details
- Book Title: The 5-Minute Pediatric Consult
- Author(s): M. William Schwartz MD; et al.
- Year of Publication: 2008
- Copyright Details: The 5-Minute Pediatric Consult, Copyright © 2008 Lippincott Williams & Wilkins.
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Copyright notice for book excerpts: Copyright © 2008 Lippincott Williams & Wilkins. All rights reserved.
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More About This Book:
Title: The 5-Minute Pediatric Consult
Authors: M. William Schwartz MD; et al.
Publisher: Lippincott Williams & Wilkins
Copyright: 2008
ISBN: 0-7817-7577-9
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