Nutritional Assessment

• Anthropometry


  The measurement of the variations of the physical dimensions and gross compositions of the human body at different age levels and degrees of nutrition
• Anthropometric measurements


  • Widely used to assess the nutritional status in individuals and population groups as an indication of stored body energy and protein mass
• Uses of Anthropometry


  • To identify mild, moderate, severe states of malnutrition
  • To identify individuals and populations at risk to malnutrition
  • To evaluate changes in nutritional status over time
  • To serve as proxy indicators of constraints to human welfare
  • To monitor nutritional problems
  • To evaluate the impact of interventions designed to enhance nutrition, health, economic and/or environmental factors
• Advantages of Anthropometry


  • Procedures may be used at the bedside, as well as in large sample sizes
  • Methods can be precise and accurate if standardized techniques are used
  • Generates historical information of nutritional status
  • Procedures identify malnutrition status along a continuum of mild to severe
  • Can screen for individuals and/or population groups at risk of malnutrition
  • Methods can be used to evaluate changes in nutritional status over time
• Limitations of Anthropometry


  • Insensitive method over short periods of time
  • Unable to detect specific nutrient deficiencies
  • Unable to differentiate changes in growth or body composition as may be induced by specific nutrients
  • Can be affected by non-nutritional factors if not taken into account, thus reducing specificity and sensitivity of anthropometric measurements
• Types of anthropometric measurements

  • Growth measurements
  • Body composition measurements
• Growth measurements


  • Head circumference (HC)
  • Recumbent length
  • Height
  • Knee height
  • Weight
  • Elbow breadth
• Body composition measurements


  • Fat (skinfold thickness)
  • Fat-free mass (mid-upper-arm muscle circumference)

  
• Head circumference


  The head circumference of a young child during the first year of life is known to increase rapidly, and slows down by the age of 36 months. Such pattern of growth makes head circumference measurement an important screening procedure in detecting head and brain growth abnormalities among children up to three years old.
• Recumbent length


  Generally applicable to children with age less than two years, or between 24 to 36 months of age who cannot stand erectly without assistance. As an index of chronic nutritional status, length can indicate stunting of a child's full growth potential.
• Height/length


  • Legs
  • Spine
  • Skull
• Knee height


  An alternative way of measuring height that is said to be correlated with stature. Knee height caliper consists of an adjustable, measuring stick with a blade attached to each end of a 90o angle. This device is most useful among adults who are unable to stand, with severe spinal curvature or other skeletal deformities.
• Arm span


  Another alternative measurement when actual height cannot be taken. Arm span is also correlated with stature, and most useful when assessing retrospective stature at young adulthood prior to age-associated loss in stature.
• Weight


  An important variable in equations predicting caloric expenditure and in indices of body composition. Weight refers to the total or exact amount of heaviness of an individual, mainly made up of muscles, fat, bone and internal organs.
• Low birth weight


  Weight at birth of <2500 grams (5.5 pounds). At population level, the proportion of infants with a low birth weight is an indicator of a multifaceted public health problem that includes long- term maternal malnutrition, ill health, hard work and poor health care in pregnancy.
• Elbow breadth


  As a measure of frame size, elbow breadth is less affected by adiposity and is said to be highly associated with lean body mass and muscle size.
• Body fat


  The size of the subcutaneous fat depot provides an estimate of total body fat. The subcutaneous fat, in turn, can be measured by the thickness of skinfold, which varies with body weight and age.

  
• Sites for measuring body fat

  • Triceps skinfold
  • Biceps skinfold
  • Subscapular skinfold
  • Suprailiac skinfold
  • Midaxillary skinfold
• Waist-hip circumference ratio (WHR)

  A simple method for describing the distribution of both subcutaneous and intra-abdominal adipose tissue. Females typically have lower WHR or lower trunk fatness, also referred to as "gynoid obesity." Males tend to show upper trunk fatness or higher WHR, also referred to as "android obesity." Central obesity is considered a risk factor in the development of certain diseases, such as coronary heart disease and type 2 diabetes mellitus.

  
• Limb fat area


  A calculated area, derived from skinfold thickness and limb circumference measurements. The limb fat area correlates with total body fat, in view of a recognition that more fat is needed to cover a large limb than to cover a smaller limb.
• Mid-upper-arm Circumference (MUAC)


  Since the arm is of both subcutaneous fat and muscle, its reduction in either component, or both, may be reflected in a decrease in the MUAC. When the amount of subcutaneous fat is small, MUAC becomes useful in diagnosing protein-energy malnutrition because changes in muscles mass are paralleled by changes in MUAC.
• Mid-upper-arm muscle circumference (MUAMC)


  The measurements of the MUAC and the triceps skinfold
• Limb fat area


  Calculated area, derived from skinfold thickness and limb circumference measurements
• Limb fat area


  Correlates with total body fat, in view of a recognition that more fat is needed to cover a large limb than to cover a smaller limb
• Mid-upper-arm Circumference (MUAC)


  The arm is of both subcutaneous fat and muscle, its reduction in either component, or both, may be reflected in a decrease in the MUAC
• MUAC


  Useful in diagnosing protein-energy malnutrition because changes in muscles mass are paralleled by changes in MUAC
• MUAC


  Valuable in screening for protein-energy malnutrition, especially when the measurement of height and weight may not be feasible
• Mid-upper-arm muscle circumference (MUAMC)


  Calculated circumference of the inner circle of muscle surrounding a small central core of bone
• MUAMC


  Used to assess total body muscle mass, and thus becomes an index of protein reserves
• MUAMC


  Calculated following the equation: MUAMC (C2) = MUA circ (C1) - (π x TSK)
• Mid-upper-arm muscle area (MUAMA)


  As an index of total body muscle mass, MUAMA reflects the true magnitude of muscle tissue change
• Anthropometric Indices


  • Head circumference-for-age
  • Weight-for-age
  • Weight-for-height or weight-for-length
  • Height-for-age
  • Body Mass Index

  
• Head circumference-for-age


  An index of chronic protein-energy malnutrition during the first two years of life
• Weight-for-age


  An index of acute malnutrition, and is largely used in protein-energy malnutrition and overnutrition
• Weight-for-height or weight-for-length


  Useful in assessing changes in nutritional status, an expression of leanness or wasting

  
• Height-for-age


  Indicates the degree of linear growth, which tells of past nutritional history or stunting
• Body Mass Index


  Measures body weight corrected for height, may be a sensitive index of current nutritional status, but cannot distinguish between excessive weight due to adiposity, muscular or edema

  
• Factors to consider in selection of anthropometric methods of evaluation

  • Objectives of the study
  • Available facilities for handling data
• Uses of anthropometric indices at the individual level


  • To track individual growth pattern over time
  • To identify and classify nutritional status by comparing with reference limits of cut-off points
  • To indicate severity or type of malnutrition according to risk categories
• Uses of anthropometric indices at the population level


  • To compare between local and international reference data when available and/or appropriate
  • To present data as frequency distribution of the anthropometric indices
  • To determine proportion of individuals in the population with indices below or above predetermined reference limits
  • To assess impact of interventions