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The etiology of malnutrition can be primary, as when the otherwise healthy individual’s needs for protein, energy, or both are not met by an adequate diet, or secondary, as a result of disease states that may lead to suboptimal intake, inadequate nutrient absorption or use, and/or increased requirements because of nutrient losses or increased energy expenditure. Protein-energy malnutrition is the most important nutritional disease in developing countries and one of the leading causes of morbidity and mortality in childhood worldwide.1,2 In the Western world primary malnutrition continues to occur with alarming frequency because of neglect or poverty. Secondary malnutrition exists as a result of chronic or acute illness.

In primary protein-energy malnutrition, calorie inadequacies generally are linked to conditions of war, social disruption, poverty, ignorance, infectious diseases, and food distribution inequalities. Therefore, socioeconomic, political, and other environmental deprivations can be considered to be the most global cause for childhood starvation with its deleterious effects on growth and development.

In the clinical setting, acute and/or chronic illness may lead to malnutrition and, if prolonged, result in failure to thrive. Although the etiology of malnutrition can be traced to an underlying pathology (ie, increased energy needs secondary to respiratory distress, fever, wound healing, or a malabsorptive state), the common pathway to a malnourished state is still a net deficiency of the nutrients required for an individual. Although dietary energy and protein deficiencies typically occur in concert, one may predominate, resulting in either kwashiorkor (primarily a protein-deficient state) or marasmus (primarily an energy-deficient state). Marasmic kwashiorkor also can occur and is the combination of chronic energy deprivation with a superimposed chronic or acute protein deficit. In both pathologic states, apathy, indifference, fatigue, and irritability are common.

There are several different criteria using weight and height to classify malnutrition, and all must be judiciously applied. The most useful and widely employed are the Waterlow classification2 and the Gomez criteria,3 which are used to distinguish a chronically malnourished or “stunted” child from an acutely malnourished or “wasted” child. An expected (or predicted) weight-for-height index is employed. This assessment allows classification of the degree of stunting (ie, decreased height-for-age, an indicator of chronic malnutrition) and wasting (ie, decreased weight-for-height, an indicator of acute malnutrition). The severity of an individual’s wasting and/or stunting is calculated as a percentage of the reference median value. The 50th percentile weight for that age and height-for-age are taken as the denominator, and the actual weight or height as the numerator. Gomez criteria assess the degree of malnutrition based on weight-for-age. The actual weight is compared to the median value (50th percentile for age) for the patient’s actual age. This criterion aids in the recognition of acute malnutrition. The Waterlow revised grading index for height-for-age and weight-for-height and the Gomez criteria can be found in Table 29-1.3,4

Table 29-1. Classifications of Malnutrition

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