Nutritional Assessment Flashcards
3 standard measurements of nutritional assessment.
Weight: easy to obtain, least measurement error, changes rapidly, trend important, unreliable in fluid overload conditions.
Height/length: accurate technique important, measure at longer intervals, length til age 2-3 years, height >2 years if standing.
Head circumferences: Birth to 36 months when brain growth is most rapid.
Standard measurements of nutritional assessment continued
Arm anthropometry: mid-arm circumference, triceps skin fold: technically difficult, can estimate muscle and fat stores, used over time.
Alternative height measurements: arm span/limb lengths: useful when standard measurements cannot be obtained, need previous measurements to trend.
WHO growth charts
0-2 years of age
CDC growth charts
After 2 years of age
BMI >2 years of age
appropriateness of body weight for height, classifying overweight: 85-95 %tile, and obesity >95th %tile or BMI >/= 30.
BMI <10th underweight
Weight for length <3 years of age
Assess child’s weight taking into account their length. underweight <5th %tile, overweight >90th %tile.
Ideal Body Weight (IBW)
Compare acute weight to median weight for length. Measures short term response to nutritional support or weight reduction therapy.
Waterloos criteria >120% is overweight, 80-90% is mild wasting, 70-80% is moderate wasting, 60-70% severe wasting.
Percent IBW underestimates malnutrition severity in children with short stature
zinc, copper and iron metabolism are closely related
if getting zinc therapy, will likely become iron deficient
Total Energy Expenditure (TEE)
TEE= BMR+ TEF+ PAL+ energy cost of growth
BMR: Basal metabolic rate: rate at which a person uses energy to maintain the basic function of the body at rest, determined by body mass and composition (60-70% of TEE) and lower than REE (10-20% lower).
TEF: Thermic Effect of Food or energy cost of digesting food (5-10%).
PAL: Physical Activity Level (20-25%).
Energy cost of growth (<5th %).
Affected by age, body size and composition and presence of illness, infection, fever, trauma
BMR: Basal Metabolic Rate
Rate at which a person uses energy to maintain the basic function of the body at rest; determined by body mass and composition (60-70% of TEE) and lower than REE (10-20% lower)
TEF: Thermic effect of food
energy cost of digesting food (5-10%
PAL: Physical Activity Level
20-25%
Energy cost of growth
<5 %
Equations to determine TEE:
DRI and RDA
DRI
DRI: Estimated Energy requirements (TEE +energy deposition)
RQ: Respiratory Quotient
ratio of CO2 production to oxygen consumption. varies depending on substrate utilization:
- RQ fat =0.7, RQ protein =0.85, RQ Carbohydrate = 1.0.
- Lipogenesis (conversion of carb to stored fate) occurs when RQ >1.
Ingestion of a carbohydrate rich diet results in increase in CO2 production and worsening respiratory insufficiency
Total energy needs = REE x disease activity factor
REE: resting energy expenditure: amount of energy required for a 24 hour period by the body during resting conditions in a thermoneutral environment.
- closely related to, but not identical to the BMR.
Equations to determine REE: WHO and Schofeld.
Measurement of REE: indirect calorimetry (clinical), and doubly labeled water method (research)
Energy Expenditure
determined by body size, body composition, food intake and physical activity
Higher weight results in higher energy requirement
via a higher REE because of a higher maintenance cost of a larger body weight
Larger body size
implies a larger fat free mass or lean body mass. taller subjects have a larger fat free mass than subjects with a short stature and fat free mass is larger in overweight and obese subjects than in lean subjects with the same stature
Lean body mass
is metabolically more active than fat mass
Severe protein calorie malnutrition
- increased total body water in relation to body weight.
- severe loss of cell mass and body fat
- increased total body Na intracellularly and extracellularly.
- total body potassium is decreased
- increase in extracellular water
- decrease in intravascular volume especially in the face of ongoing diarrhea and vomiting
