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INTRODUCTION

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  • Malnutrition is a consequence of nutrient imbalance resulting from inadequate intake, absorption, or utilization of protein and energy. Undernutrition can result in changes in subcellular, cellular, or organ function that increase the individual’s risks of morbidity and mortality.

  • For information on overnutrition or obesity, see Chap. 58.

  • Nutrition screening provides a systematic way to identify individuals in any care environment who need a detailed nutrition assessment.

  • Nutrition assessment is the first step in developing a nutrition care plan. Goals of nutrition assessment are to identify the presence of factors associated with an increased risk of developing undernutrition and complications, estimate nutrition needs, and establish baseline parameters for assessing the outcome of therapy.

  • This assessment should include a nutrition-focused history, a physical exam including anthropometrics, and laboratory measurements.

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CLINICAL EVALUATION

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  • Medical and dietary history should include weight changes within 6 months, dietary intake changes, gastrointestinal (GI) symptoms, functional capacity, and disease states.

  • Physical examination should focus on assessment of lean body mass (LBM) and physical findings of vitamin, trace element, and essential fatty acid deficiencies.

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ANTHROPOMETRIC MEASUREMENTS

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  • Anthropometric measurements are physical measurements of the size, weight, and proportions of the human body used to compare an individual with normative population standards. The most common measurements are weight, stature, head circumference (for children younger than 3 years of age) waist circumference, and measurements of limb size (eg, skinfold thickness and midarm muscle and wrist circumferences), along with bioelectrical impedance analysis (BIA).

  • Interpretation of actual body weight (ABW) should consider ideal weight (IBW) for height, usual body weight (UBW), fluid status, and age. Change over time can be calculated as the percentage of UBW. Unintentional weight loss, especially rapid weight loss (5% of UBW in one month or 10% of UBW in 6 months), increases risk of poor clinical outcome in adults.

  • The best indicator of adequate nutrition in children is appropriate growth. Weight, stature, and head circumference should be plotted on the appropriate growth curve and compared with usual growth velocities. Average weight gain for newborns is 10 to 20 g/kg/day (24–35 g/day for term infants and 10–25 g/day for preterm infants).

  • Body mass index (BMI) is another index of weight-for-height that is highly correlated with body fat. Interpretation of BMI should include consideration of gender, frame size, and age. BMI values greater than 25 kg/m2 are indicative of overweight, and values less than 18.5 kg/m2 are indicative of undernutrition. BMI is calculated as follows:

    Body weight (kg)/[height (m)]2 or [Body weight (lbs) × 703]/[height (in)]2

  • Measurements of skinfold thickness estimate subcutaneous fat, midarm muscle circumference estimates skeletal muscle mass, and waist circumference estimates abdominal fat content.

  • BIA is a simple, noninvasive, and relatively inexpensive way to assess LBM, TBW, and water distribution. It is based on differences between fat tissue and lean tissue’s resistance to conductivity. Hydration status should be ...

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