12. Malnutrition / D.G. Patel 

Nutrition may be defined as the process by which an organism utilizes food. This complex process involves ingestion, digestion, absorption, transport, utilization and excretion. Any alteration in one or many of these factors can produce malnutrition. Globally, primary malnutrition due to lack of food is the most common cause of malnutrition. Malnutrition in the Western world is mainly due to inadequate intake of nutrients, malabsorption and/or the hypercatabolism accompanying a critical illness. Protein-energy undernutrition is increasingly recognized in eating disorders such as anorexia nervosa.   

The malnutrition associated with gastrointestinal disorders is usually multifactorial and varies with the nature and activity of the disease. 

1. Lack of food intake due to anorexia or food-related symptoms such as dysphagia, pain or vomiting. 

2. Maldigestion due to pancreatic disease. Deficiency of bile salts due to cholestatic hepatobiliary disease or to ileal disease leads to maldigestion of triglyceride and lipid-soluble vitamins. Steatorrhea (fat malabsorption) produces negative caloric balance and deficiency of fat-soluble vitamins. 

3. Malabsorption due to mucosal disease of the small intestine or loss of surface area due to intestinal bypass, fistula or resection. 

4. Excessive loss of nutrients, as in protein-losing enteropathy and loss of zinc in diarrheal illness. 

5. Therapeutic agents that may selectively affect nutrient utilization ^_ e.g., cholestyramine use for bile acid-induced diarrhea can worsen steatorrhea. 

6. Alcoholism ^_ an extremely common cause of malnutrition in the Western world. Social and economic status, behavior problems, isolation and depression cause reduced intake of nutrients. Alcoholics rarely consume a well-balanced diet and depend very heavily on "empty" calories from alcohol. Protein and vitamin deficiencies, particularly of the B-complex group, are extremely common. Alcohol is a toxic agent that even in the presence of adequate nutritional intake can produce damage to the pancreas, liver and small bowel mucosa, aggravating malnutrition. 

1. Weight loss in the absence of edema is a good indicator of energy deficiency. 

2. Muscle wasting, particularly in the temporal area and dorsum of the hand between thumb and index finger, suggests protein-calorie deficiency. 

3. Dry, scaly skin with pigmentation results from vitamin and trace metal deficiency. 

4. Angular mouth fissure (cheilosis) is due to riboflavin deficiency. 

5. Glossitis and depapillation of the tongue are due to B₁₂, folate or iron deficiency. 

6. Hepatomegaly may be due to fatty liver, a common finding in protein malnutrition or alcoholism. 

7. Peripheral neuropathy (decreased position sense), decreased vibration sense or ataxia may result from B₁₂ deficiency. 

8. Weakness and paresthesia of the legs are signs of nutritional polyneuropathy, especially in alcoholics (due to thiamine or pyridoxine deficiency). 

9. Anemia due to iron, folate or B₁₂ deficiency or chronic disorders. 

10. Peripheral edema. 

11. Hypoalbuminemia.