Basics
Description
- Malabsorption is characterized as a syndrome, as opposed to a disease entity, and is defined as any state in which there is a disturbance of digestion and/or absorption of nutrients across the intestinal mucosa.
- The classical symptoms of malabsorption include chronic diarrhea, abdominal distention, and failure to thrive.
Epidemiology
Depends on the underlying disease causing malabsorption
Etiology
The most common causes of malabsorption in developed countries are as follows:
- Postenteritis syndrome
- Cow 's milk protein intolerance
- Giardiasis
- Celiac disease
- Cystic fibrosis
- Inflammatory bowel disease (IBD)
Pathophysiology
- Depends on the nutrient affected
- Carbohydrate
- Monosaccharide: congenital glucose-galactose deficiency, fructose intolerance
- Disaccharide: lactase deficiency (congenital or acquired), sucrase-isomaltase deficiency
- Polysaccharide: amylase deficiency (congenital or acquired)
- Fat
- Bile salt deficiency: cholestasis, resection of terminal ileum
- Exocrine pancreatic insufficiency: cystic fibrosis, chronic pancreatitis
- Inadequate surface area: celiac disease, flat villous lesions
- Protein
- Protein-losing enteropathy: intestinal lymphangiectasia, congenital heart failure
- Exocrine pancreatic insufficiency: cystic fibrosis, Shwachman-Diamond syndrome
- Inadequate surface area: celiac disease
- According to the place where the alteration occurs
- Mucosal abnormality
- Anatomic: post-enteritis syndrome, celiac disease, IBD
- Functional: disaccharidase deficiencies
- Luminal abnormality
- Exocrine pancreatic insufficiency: cystic fibrosis, Shwachman-Diamond syndrome
- Bile salt insufficiency: biliary cholestatic liver disease, ileal resection
- Anatomic abnormality
- Short gut: surgical resection
- Motility disturbance: intestinal pseudo-obstruction
Diagnosis
History
- GI symptoms
- Common in patients with malabsorption syndromes
- Range from mild abdominal gaseous distention to severe abdominal pain and vomiting
- Chronic or recurrent diarrhea is by far the most common symptom.
- Abdominal distention and watery diarrhea, with or without mild abdominal pain associated with skin irritation in the perianal area due to acidic stools, are characteristic of carbohydrate malabsorption syndromes.
- Fat malabsorption can present with bulky, foul-smelling stools that are oily and thus float in water. Abdominal distention, increased gas, weight loss, and increased appetite are also seen.
- Periodic nausea, abdominal distention, pain, and diarrhea are common in patients with chronic Giardia infections.
- Vomiting, with moderate to severe abdominal pain and bloody stools, is characteristic of protein sensitivity syndromes.
- Abdominal pain or irritability (particularly seen in celiac disease)
- Stool characteristics
- Frequent loose watery stools may indicate carbohydrate intolerance.
- Bulky, greasy, or loose foul-smelling stools indicate fat malabsorption.
- In protein malabsorption, stools may be normal or loose.
- Bloody stools are seen in patients with cow 's milk protein allergy, infection, and IBD.
- Other symptoms
- Failure to thrive caused by malabsorption of carbohydrates, fats, or proteins
- Anemia, with weakness and fatigue, due to inadequate absorption of vitamin B12, iron, and folic acid
- Edema, due to decreased protein absorption and hypoalbuminemia
- Muscle cramping due to decreased vitamin D causing hypocalcemia and decreased potassium levels
Physical Exam
- Malabsorption syndromes should be considered during the workup for failure to thrive, malnutrition, poor weight gain, or delayed puberty.
- In particular, they should be suspected in infants with weight loss or little weight gain since birth and in infants with low weight and weight-for-height percentiles.
- Signs of malnutrition, including reduced subcutaneous fat, paleness, angular cheilosis, and muscle weakness
- Abdominal distention, increased bowel sounds
- Rash around mouth and/or anus are commonly seen.
Diagnostic Tests & Interpretation
Lab
- Stool analysis
- The presence of reducing substances and pH <5.5 indicates that carbohydrates have not been properly absorbed.
- The level of quantitative stool fat and the amount of fat intake in the diet should be measured and monitored for 3 days using special stains; a coefficient of fat absorption is calculated using the following equation: View OriginalView Original
- Normal values for the coefficient of fat absorption: >93% in children and adults, >85% in infants, >67% in premature infants
- Moderate fat malabsorption ranges from 60 to 80%.
- Fat absorption of <50% indicates severe malabsorption.
- The presence of large serum proteins in the stool, such asα1 antitrypsin, indicates leakage of serum protein. A 24-hour stool collection forα1 antitrypsin (along with a serum level) serves as a screening test for protein-losing enteropathy.
- Exam of the stool for ova and parasites or testing for the stool antigen may reveal the presence of Giardia species.
- If bile acid malabsorption is suspected, quantitative conjugated and unconjugated bile acids may be measured in stool, although this test is not commonly available or used.
- Other laboratory studies
- CBC
- May reveal anemia in patients with iron, folate, and vitamin B12 malabsorption
- Neutropenia is seen in patients with Shwachman-Diamond syndrome.
- Total serum protein and albumin levels
- May be lower than reference range in syndromes in which protein is lost or not absorbed, particularly in protein-losing enteropathy and pancreatic insufficiency
- With fat malabsorption or ileal resection, fat-soluble vitamin levels in the serum are low.
- With bile acid malabsorption, levels of LDL cholesterol may be low.
- Serum calcium may be low due to vitamin D and amino acid malabsorption.
- Serum vitamin A, E, and carotene may be low due to bile salt deficiency and impaired fat absorption.
- Other studies must be performed when a specific disease is suspected (e.g., mucosal biopsy for celiac disease, sweat test for cystic fibrosis, or appropriate workup for IBD).
- Urine analysis should be done to rule out proteinuria in patients with low albumin levels.
- An upper GI radiographic series and/or a lactulose breath test can be performed to look for small bowel dilation due to bacterial overgrowth.
- Genetic testing may be performed for identification of inherited malabsorption syndromes.
- If tissue samples are acquired through a biopsy, ultrastructural analysis may be performed using electron microscopy.
Differential Diagnosis
- Pancreatic disorders
- Cystic fibrosis
- Shwachman syndrome
- Johanson-Blizzard syndrome
- Chronic cholestasis
- Biliary atresia
- Vitamin E deficiency
- Alagille syndrome
- Infectious diarrhea
- Giardiasis
- Cryptosporidiosis
- Mucosal defect
- Celiac disease
- Crohn disease
- Postinfectious diarrhea
- Congenital brush border enzyme deficiencies
- Glucose-galactose transporter deficiency
- Sucrase-isomaltase deficiency
- Microvillus inclusion disease
- Abnormal intestinal lymphatic drainage
- Primary intestinal lymphangiectasia
- Secondary intestinal lymphangiectasia
Treatment
- Overall, nutritional support is paramount.
- Specific treatment depends on etiology, for example, gluten-free diet for celiac disease, metronidazole for Giardia infection, or removal of the offending agent in a case of food intolerance.
Ongoing Care
Complications
- Complications of malabsorption vary according to the underlying disease, but malnutrition and its consequences may worsen progressively if the cause is not determined and appropriate treatment prescribed.
- Frequent complications of malabsorption and malnutrition include growth failure, vitamin and micronutrient deficiency (zinc, magnesium, calcium), bone disease, hypoproteinemia and edema, essential fatty acid deficiency, perianal dermatitis, immune dysfunction, and anemia.
Additional Reading
- Ali SA, Hill DR. Giardia intestinalis. Curr Opin Infect Dis. 2003;16(5):453 " 460. [View Abstract]
- Crittenden RG, Bennett LE. Cow 's milk allergy: a complex disorder. J Am Coll Nutr. 2005;24(6)(Suppl):582S " 591S. [View Abstract]
- Dodge JA, Turck D. Cystic fibrosis: nutritional consequences and management. Best Pract Res Clin Gastroenterol. 2006;20(30):531 " 546. [View Abstract]
- Fasano A, Catassi C. Coeliac disease in children. Best Pract Res Clin Gastroenterol. 2005;19(3):467 " 478. [View Abstract]
- Pietzak MM, Thomas DW. Childhood malabsorption. Pediatr Rev. 2003;24(6):195 " 206. [View Abstract]
Codes
ICD09
- 579.9 Unspecified intestinal malabsorption
- 579.8 Other specified intestinal malabsorption
- 579.0 Celiac disease
ICD10
- K90.9 Intestinal malabsorption, unspecified
- K90.4 Malabsorption due to intolerance, not elsewhere classified
- K90.0 Celiac disease
- K90.89 Other intestinal malabsorption
SNOMED
- 32230006 Malabsorption syndrome (disorder)
- 302921006 Malabsorption due to intolerance to protein (disorder)
- 396331005 Celiac disease (disorder)
- 197491004 Intestinal malabsorption of carbohydrate (disorder)
- 197490003 Intestinal malabsorption of protein (disorder)
FAQ
- Q: Why do patients with malabsorption become anemic?
- A: Patients with malabsorption can become deficient in vitamin B12, iron, and folic acid and in turn can become anemic.
- Q: Why do patients with celiac disease develop symptoms of malabsorption?
- A: Celiac disease leads to inflammation of the small bowel mucosa and villous atrophy. In turn, the absorptive capacity of the bowel is decreased.