Malnutrition, Measurement of

Assessment of Nutritional Status

Nutritional status can be measured at the individual or population level. Population-based assessments are typically performed to measure the extent of malnutrition in a community, identify high-risk groups, and estimate the number of people requiring interventions such as supplementary and therapeutic feeding. Estimates of the burden of malnutrition are important at the national and local levels to define strategies for improving the health of the population.

[Page 631]Methods to assess malnutrition include anthropometry, biochemical indicators (e.g., decrease in serum albumin concentration), and clinical signs of malnutrition (e.g., edema, changes in the hair and skin, visible thinness). Anthropometry is the preferred method to assess malnutrition in both individual people and surveyed populations because body measurements are sensitive over the full spectrum of malnutrition, while biochemical and clinical indicators are useful only when malnutrition is advanced. The purpose of the assessment should guide the choice of measurement methods.

Common anthropometric indicators of malnutrition in childhood include combinations of body measurements (e.g., either length or height combined with weight) according to age and sex. Anthropometric measurements of children below the age of 5 years are used to draw conclusions about the nutritional well-being of the population in which they live, because children are more vulnerable to adverse environments and respond more rapidly than adults to dietary changes.

To interpret anthropometric data and determine an individual child's level of malnutrition, the child's height and weight are compared with reference curves of height-for-age, weight-for-age, and weight-for-height. The internationally accepted references were developed by the Centers for Disease Control and Prevention (CDC) using data collected from a population of healthy children in the United States. More recently, the World Health Organization (WHO) released international standards for child growth that were based on a pooled sample from six countries. Anthropometric data can be plotted using software available from the CDC (http://www.cdc.gov/epiinfo) or WHO (http://www.who.int/childgrowth/software). The internationally recommended indicators used to characterize the different types of malnutrition in childhood include the following:

• Low height-for-age: Assess stunting or shortness
• Low weight-for-height: Assess wasting or thinness
• Low weight-for-age: Assess underweight

Stunting reflects a failure to reach one's linear growth potential (maximum height) because of chronic malnutrition due to either inadequate intake of food or recurrent illness; wasting, in contrast, indicates recent loss of weight, usually as a consequence of famine or severe disease. Underweight reflects both wasting and stunting, and thus in many cases, it reflects a synthesis of undesirable body proportions and reduced linear growth. The choice of anthropometric indicator depends on the purpose of the assessment. For example, in emergency situations, weight-for-height is the index most often used, because wasting has the greatest potential for causing mortality or widespread morbidity. Other anthropometric indices, such as midupper-arm circumference and triceps skinfold thickness, are some times used but are less reliable.

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