Malabsorptive disorders of childhood.

1. Rana F. Ammoury, MD* 2. Joseph M. Croffie, MD† 1. *Division of Pediatric Gastroenterology, Hepatology, and Nutrition, Indiana University School of Medicine, Indianapolis, Ind. 2. †Editorial Board After completing this article, readers should be able to: 1. Understand the physiology and pathophysiology of malabsorption. 2. Describe the various manifestations of malabsorption. 3. Recognize the extensive differential diagnosis for malabsorption. 4. Plan an investigative approach for children who present with symptoms suspicious for malabsorption. The primary function of the small intestine is digestion and absorption of ingested nutrients. The term malabsorption refers to impairment in the absorption of one or more substances by the small intestine. Malabsorptive disorders include numerous clinical entities that may result in chronic diarrhea, abdominal distention, and failure to thrive. Although diarrhea is a key feature of malabsorption, it may not be apparent at presentation; the only symptom may be poor growth. The pediatrician must be able to recognize the various manifestations of malabsorption (Table 1) to establish an early diagnosis and initiate treatment with the aim of avoiding long-term complications of malnutrition. It becomes necessary, therefore, for the physician to understand the physiology and pathophysiology of digestion and absorption. View this table: Table 1. Signs and Symptoms of Malabsorption Most nutrients cannot be absorbed in their natural form and need to be digested. Food is chemically reduced by various enzymes to digestive end products small enough to participate in the absorption process, which then are transported across the intestinal epithelium by active transport, passive transport, facilitated diffusion, or endocytosis. Disruption of these physiologic stages can lead to maldigestion, malabsorption, or both. ### Carbohydrates Beyond infancy, starch makes up much of the ingested carbohydrates. In small amounts, lactose and sucrose make up the rest. Much ingested starch is found in wheat, rice, and corn as polysaccharides. The two chief constituents of starch are amylose, which …