Malnutrition can arise from primary or secondary causes, resulting in the former case from inadequate or poor-quality food intake and in the latter case from diseases that alter food intake or nutrient requirements, metabolism, or absorption. Primary malnutrition occurs mainly in developing countries and under conditions of political unrest, war, or famine. Secondary malnutrition, the main form encountered in industrialized countries, was largely unrecognized until the early 1970s, when it was appreciated that persons with adequate food supplies can become malnourished as a result of acute or chronic diseases that alter nutrient intake or metabolism, particularly diseases that cause acute or chronic inflammation. Various studies have shown that protein-energy malnutrition (PEM) affects one-third to one-half of patients on general medical and surgical wards in teaching hospitals. The consistent finding that nutritional status influences patient prognosis underscores the importance of preventing, detecting, and treating malnutrition.
Definitions for forms of PEM are in flux. Traditionally, the two major types of PEM have been marasmus and kwashiorkor. These conditions are compared in Table 97-1. Marasmus is the end result of a long-term deficit of dietary energy, whereas kwashiorkor has been understood to result from a protein-poor diet. Although the former concept remains essentially correct, evidence is accumulating that PEM syndromes are distinguished by two main features: insufficient dietary intake and underlying inflammatory processes. Energy-poor diets with minimal inflammation cause gradual erosion of body mass, resulting in classic marasmus. By contrast, inflammation from acute illnesses such as injury or sepsis or from chronic illnesses such as cancer, lung or heart disease, or HIV infection can erode lean body mass even in the presence of relatively sufficient dietary intake, leading to a kwashiorkor-like state. Quite often, inflammatory illnesses impair appetite and dietary intake, producing combinations of the two conditions.
TABLE 97-1Comparison of Marasmus/Cachexia and Kwashiorkor/Acute Malnutrition |Favorite Table|Download (.pdf) TABLE 97-1Comparison of Marasmus/Cachexia and Kwashiorkor/Acute Malnutrition
|Feature ||Marasmus (Starvation–Related Malnutrition) and Cachexia (Chronic Disease–Related Malnutrition) ||Kwashiorkor (Acute Disease– or Injury–Related Malnutrition)a |
|Clinical setting ||Prolonged ↓ energy and protein intake with or without systemic inflammation ||Acute ↓ energy and protein intake with substantial systemic inflammation |
|Time course to develop ||Months or years ||Weeks |
|Clinical features ||Starved appearance (body mass index <18.5) ||Normal body mass index (although loss of body mass may be masked by edema) |
| ||Reduced triceps skinfold ||Easy hair pluckabilityb |
| ||Reduced midarm muscle circumference ||Edema |
|Laboratory findings ||Serum albumin normal (marasmus, no inflammation) or decreased (cachexia, with inflammation) ||Serum albumin <2.8 g/dL |
| || ||Total iron-binding capacity <200 μg/dL |
| || ||Lymphocytes <1500/μL |
| || ||Anergy |
|Clinical course ||Reasonably preserved responsiveness to short-term stress ||Infections |
| ||Poor wound healing, decubitus ulcers, skin breakdown |
|Mortality risk ||Low unless related to underlying disease ||High |
|Diagnostic criteria ||Triceps skinfold <3 mm ||Serum albumin <2.8 g/dL |
| ||Midarm muscle circumference <15 cm || |
At least one of the following:
Poor wound healing, decubitus ulcers, or skin breakdown
| || ||Easy hair pluckabilityb |
| || ||Edema |
Pop-up div Successfully Displayed
This div only appears when the trigger link is hovered over.
Otherwise it is hidden from view.