Disorders of Malabsorption

Disorders of malabsorption constitute a broad spectrum of diseases with multiple etiologies and varied clinical manifestations. All are associated with diminished intestinal absorption of one or more dietary nutrients.

Malabsorption can result from either a defect in the nutrient digestion in the intestinal lumen or mucosal absorption

CLINICAL APPROACH TO A CHILD WITH SUSPECTED MALABSORPTION

The clinical features depend on the extent and type of the malabsorbed nutrient.

The common presenting features, especially in toddlers with malabsorption, are diarrhea, abdominal distention, and failure to gain weight, with a fall in growth chart percentiles.

Physical findings include the disappearance of the subcutaneous fat, muscle wasting, and the appearance of skin being too loose for the child

Specific findings on examination may guide toward a particular disorder;

edema is usually associated with protein-losing enteropathy,

digital clubbing with cystic fibrosis and celiac disease,

perianal excoriation and gaseous abdominal distention with carbohydrate malabsorption,

perianal and circumoral rash with acrodermatitis enteropathica,

abnormal hair with Menkes syndrome, and

the typical facial features diagnostic of the Johannson-Blizzard syndrome.

Clinical history alone may not be sufficient to make a specific diagnosis, but can direct the pediatrician toward a more structured and rational investigative approach. Diarrhea is the main clinical expression of malabsorption The nature of the diarrhea may be helpful:

explosive watery diarrhea suggests carbohydrate malabsorption;

loose, bulky stools are associated with celiac disease; and

pasty and yellowish offensive stool suggests an exocrine pancreatic insufficiency.

Investigations:

The choice of investigative studies is usually guided by the history and physical examination. In a child presenting with diarrhea, the initial work-up should include

stool occult blood and leukocytes to exclude inflammatory disorders,

stool microscopy and antibody tests for parasites such as Giardia,

stool pH and reducing substance for carbohydrate malabsorption, and

quantitative stool fat examination to identify fat malabsorption

A complete blood count including peripheral smear for microcytic anemia, lymphopenia (lymphangiectasia), neutropenia (Shwachman syndrome), and acanthocytosis (abetalipoproteinemia) is useful.

If celiac disease is suspected, serum immunoglobulin A (IgA) and tissue transglutaminase levels should be determined.

Depending on the initial investigation results, more specific investigations can be planned