anthropometry asessment

• Body composition


  Term to describe the body from a chemical perspective, in terms of elements, molecules and compounds, from a tissue and organ perspective, or in terms of compartments defined by their physical characteristics and functions
• Body composition


  • To discriminate between fat, muscle, bone mineral and fluid spaces

  
• Lean body mass (LBM)


  Combines lean with water
• Fat-free-mass (FFM)


  Combines all but fat into a single compartment
• Stature


  Part of anthropometric assessment and body composition
• Stature measurement


  1. Best with a purpose-designed stadiometer

  2. 2 measurements, repositioning of the subject to confirm reliability

  3. Third taken if the first two differ by 2 cm or more - measurement error or poor technique

  4. Standardized the time of day for all repeated measures if different occasions

  
• Total body water (TBW)


  Measure the mass of water within the body
• Intracellular water


  TBW is distributed between the fluids inside and outside cells
• Whole body counting (total body counting)

  Measures the amount of naturally radioactive potassium 40 (40K) in the body (total body potassium or TBK)
• Extracellular water (ECF)


  More easily quantified by a tracer-dilution approach
• Dual-energy x-ray absorptiometry (DXA)


  Principle: An x-ray beam with two energy spectra (analogues to the light of two colours) is passed through the body towards a detector
• Muscle mass


  Important to assess muscle loss especially among the population at risk of malnutrition including the elderly
• Creatinine


  A metabolite of creatine, 95% found in skeletal muscle, close to 1.7% of the creatine pool is eliminated as urinary creatinine daily
• Creatinine excretion


  • May be used to estimate creatine pool size to infer muscle mass
  • Dietary creatine may contribute to creatinine excretion and so must be taken into account or minimised
• Bioelectrical impedance methods (BIA)

  • Low-cost, portable option for body composition assessment
  • Principle: electrical impedance of the body reflects TBW. Alternate current is passed through the body from electrodes placed at the extremities of arms and legs
  • Results may depend on the status of hydration and may be unreliable in pregnancy
  • Should not be used in subjects with pacemaker
• Anthropometric indicators


  To relate adiposity and lean mass
• Body mass index (BMI)

  Widely used to classify individuals into groups associated with health-related risk; often used to assign nutrition research subjects into 'normal' and 'overweight' groups
• BMI


  • Variations are not solely dependant on adiposity → BMI-based prediction of BC compartments such as fat mass are rather poor (poor proxy of fat mass), BMI may have variations in measurement tools and techniques
  • However, is the quickest, reliable and simple technique to measure nutritional status through body weight status

  
• Waist circumference, Waist:Hip ratio & Waist:Height ratio


  Offer a predictive association with CV and metabolic disease (central/visceral adiposity)
• Waist circumference measurement


  1. Measured at the midpoint between the lower margin of the last palpable rib and the top of the iliac crest

  2. Hip circumference is measured around the widest portion of the buttocks

  3. Measurement should be made at the end of expiration and should be repeated, a third taken if the difference between two measurements differ by 2 cm
• Neck circumference


  Associated with sleep apnea, common in obesity
• Malnutrition in children


  • Presents in a number of ways, depending both on the age at which occurs and its duration
  • Several indices based on height, mass and age may help to determine the presence and history of under-nutrition in children and these rely on reference to data from the well-nourished population (ref: growth chart)
  • Height is generally less susceptible to undernutrition than body mass
• Mid-upper arm circumference (MUAC)


  • Valuable screen for undernutrition
  • May be used with weight for height in children to identify current malnutrition especially PEM in children
  • To identify nutritionally compromised adults
  • Measured on the triceps muscle at the midpoint between shoulder and elbow, usually on non-dominant arm
• Skinfold measurement


  • Useful to indicate subcutaneous adiposity
  • Measurement sites varying in location including biceps, triceps, sub-scapular, supra-iliac, abdominal, thigh, calf
  • Using purpose-designed skinfold callipers to measure the thickness of a pinch of skin
• Mid-upper arm circumference (MUAC)

  • The arm contains subcutaneous fat and muscle
  • A low in MUAC may therefore reflect either a low in muscle mass or subcutaneous fat or both
  • Changes in MUAC measurement can also be used to monitor progress during nutritional therapy
  • Correlate positively with changes in weight
• Mid-upper arm circumference (MUAC) measurement


  1. With arm relaxed to the site and palms facing the thigh, a non-stretchable measuring tape is placed around the arm perpendicular to the long axis of the arm and at the level of the triceps SF site

  2. Tape is wrapped gently but firmly ensuring the arm is not squeezed

  3. Measurement recorded to the nearest 0.1cm
• Subscapular skinfold (SSF)


  • The skinfold measurement taken with the fold running obliquely downwards at the Subscapular skinfold site
  • Subject position: The subject assumes a relaxed standing position with the arms hanging by the sides
  • Location: The line of the skinfold is determined by the natural fold lines of the skin
• Actual body weight (ABW)

  • When the subject can stand unassisted using a calibrated scale
  • Non-ambulatory patients who are unable to stand, specialized scales can be used such as chair scale, or bed scale
  • The most accurate time taken is in the morning after voiding
• Estimated body weight (EBW)


  When ABW is unable to be measured, use estimation formulas by the inclusion of various body parts measurements

  
• Targeted body weight (TBW)


  • The body weight goal needs to be achieved either short-term or long-term
  • TBW may or may not be the ideal body weight (IBW) as the body weight needs to decrease or increase healthily
• Ideal body weight (IBW)

  • The TBW at which nutritional requirements are met
  • Lies within the normal BMI range
  • If the patient is underweight, the lower limit of the normal BMI range is used
  • If the patient is overweight/obese, the upper limit of the normal BMI range is used
  • The most common practice is using the mid-normal BMI
• Dosing body weight (DW)


  • A type of AdBW for obesity and underweight
  • Use for calculating the dose of indicated drugs (weight-based drugs)
  • For obese, use the AdBW for obesity
  • For underweight, use weight at BMI +2
• Estimation of anthropometry in specific condition

  • Paraplegia and non paraplegia
  • Amputation
  • Dry weight (edema-free BW or dry BW)
• Dry weight (edema-free BW or dry BW)

  • ABW minus the weight of excessive body fluid
  • Commonly associated with peripheral edema, ascites, and chronic kidney disease (CKD)
• Adjusted body weight (AdBW)

  • Adjusted for fluid (peripheral edema, ascites, chronic kidney disease)
  • Adjusted for amputation