Anthropometric Assessment

Which method would give us the best estimate of usual intake of fruits and vegetables?

• dietary screener focused on citrus consumption by season

• validated 12-month food frequency questionnaire

• two 24-hour dietary recalls in the same week

• observed, weighed food record conducted by trained enumerator

validated 12-month food frequency questionnaire

Which of the following are true about 24-hour recalls?

• may be affected by ability of participant to recall their foods and beverages

• provide more accurate estimates of total energy and nutrient intake

• generally unaffected by social desirability bias (bias that comes from the idea that some food choices are more healthy)

• all of the above

• first two options only

first two options

What is anthropometry?

measurement of body size, weight, and proportions

What is anthropometry used to assess (3)?

1. physical growth in relation to appropriate reference data

2. nutritional status (especially related to obesity/wasting)

3. body composition using predictive equations

What are the advantages for anthropometry for nutritional assessment (2)?

1. techniques are simple, safe, inexpensive, and easy to train people to take them

2. equipment is relatively inexpensive and portable

What are the limitations for using anthropometry for nutritional assessment (3)?

1. not specific to particular deficiencies or excess intake

2. not sensitive to recent changes in nutritional conditions

3. must be interpreted in context (need to have a reference population to compare them to or knowledge of individual history in terms of their weight)

Why are anthropometric measures important in children?

in general helps to assess malnutrition or over nutrition in children and they have major developmental milestones during this life stage, making it even more important

• wasting (low weight for length) → associated with increased risk of mortality and infectious illness

• stunting (low height for age) → associated with increased risk of infectious illness, mortality, poor cognitive development, low school performance, and lower earnings among adults

• overweight (high weight for length)→ greater risk for obesity, diabetes, and other chronic diseases

Describe the way children grow.

saltatory growth (grows in jumps)

• infants grow in spurts (up to 2.5 cm/day)

• growth occurs in sleep (sleep more during growth spurt days)

• can be other periods where they have no measurable growth

• weight and head circumference track alongside with length growth saltations

Where does infant/children growth occur?

at the growth plates in the long bones

How many activity zones are within the growth plates?

5 activity zones

Describe the activity in the growth plate along the long bones in growing children/infants.

cells in the growth plates transition from resting state (RZ) → proliferative (PZ) → hypertrophic state (HZ) → ossification zone (OZ) which is where mineralization occurs

• requires a good amount of nutrients to occur

What is a nutritional deficiency known to limit growth?

Vitamin D deficiency

• can act as a nuclear hormones receptor ligand, impacting nuclear transcription if there is not enough

• can result in rickets

What other nutritional deficiencies besides vitamin D are known to limit growth (7)?

1. Ca

2. Zn

3. I (iodine)

4. Protein

5. Energy

6. Indirect Pathways (biological stress, immune function, inflammation, growth hormone production)

7. excess nutrients (ex. iron)

What other factors impact growth (3)?

1. frequent/chronic infections

2. malabsorption conditions

3. stress

What is stature?

distance from the crown of the head to the heel, either standing or lying down

• < 24 months age: recumbent length (laying down)

• > 24 months age: standing height

What tools are used to measure stature (2)?

1. length board

2. stadiometer

What is the Frankfort plane?

reference line used to standardize head positioning during measuring their stature

What does weight measure?

measures total body mass of all body compartments (fat, bone, body water, muscle)

Why do we measure head circumference?

it is an indicator of brain size and development in infants

• growth charts are available to monitor trends

• less prone to measurement errors compared to recumbent length

What is MUAC?

mid-upper arm circumference

• reflects the size of the muscle, adipose, and bone tissue

• low MUAC may reflect wasting/acute malnutrition

What are five sources of random errors that can occur during anthropometry?

1. inconsistent measurement techniques

2. instrument precision

3. movement artifacts (breathing) and subject positioning

4. variation in stomach, bladder, or bowel contents

5. prandial variation (recent meals)

What can we do to fix/mitigate the five sources of random errors that occur during anthropometry?

1. inconsistent measurement techniques → train and standardize anthropometrists

2. instrument precision → use high quality measurement instruments

3. movement artifacts, subject positioning → use consistent methods to position subjects and always wait until the subject is calm

4. variation in stomach, bladder, or bowel contents → measure individuals after a fast or after voiding

5. prandial variation → measure individuals in fasted state

What are three sources of systematic errors in anthropometry?

1. improper measurement techniques

2. equipment bias

3. diurnal variation

What can we do to fix/mitigate the three sources of systematic errors in anthropometry?

1. improper measurement techniques → train and standardize anthropometrists

2. equipment bias → calibrate instruments frequently, maintain instruments in good condition

3. diurnal variation → measure all subjects at the same time of day

What are anthropometric indices?

combinations of 2 measurements of body size OR 1 measurement of body size relative to age

• help to provide context if someone wants to understand how well their child is growing

What are common anthropometric indices? (4)

1. BMI

2. weight for age → underweight

3. height for age → stunting

4. weight for length → wasting

Are the BMI values used as a reference for adults >20 years old the same or different for kids?

different

• BMI (weight in kg)/(height in cm)² is used as a indicator of overweight or thinness

• in children BMI for age is an index used to evaluate child growth

What are some characteristics surrounding growth charts?

• separate charts for girls and boys

• made by either by WHO or CDC

What indices do the CDC growth charts for children 0-36 months include? (4)

1. weight for age

2. height for age

3. weight for height

4. head circumference for age

What indices do the CDC growth charts for children 2-20 years include? (3)

1. weight for age

2. height for age

3. BMI for age

What are percentile?

rank the position of an individual on a particular reference distribution

• percentile represents the percentage/extent in which one has more or the same value compared to the reference population

• ex: a child of a given age and sex whose BMI falls on the 90th percentile line has a BMI the same or more than 90% of the reference population children of the same age and sex

What is a growth reference?

• data on the characteristics of a well-defined population

• indicates “what is” not “what should be”

• ex: CDC growth reference

What is a growth standard?

• data on the characteristics of a selected population

• indicates “what should be” not “what is”, implying something desirable

• ex: WHO growth standards

What is the CDC growth reference based off of?

• data from NHES and NHANES in the US (5 cross sectional sounds of data collection over 30 years) (2000)

• newer data from NHANES was excluded for older children due to growing obesity epidemic

• typically racially and ethnically diverse

• contains information on breastfed vs non-breastfed infants

What are the WHO growth standards based on?

• data collected from 6 countries (2006)

• based on “prescriptive” feeding practices and risk factors

• longitudinal data collected on children from birth to 2 years and 2-5 was cross-sectional data collection

• all families had good access to health care

What six countries were used for data collection in order to help create the WHO growth charts?

1. Brazil

2. Ghana

3. India

4. Norway

5. Oman

6. United States

linear growth was nearly identical among children in all 6 countries

What are the two different CDC growth reference charts?

• 0-36 months

• 2-20 years

What are the two different charts for the WHO growth standards?

• 0-5 years

• 5-18 years

Which growth chart (CDC vs WHO) are used in the US for one that is 0-2 years old? 2-5 years old? 5-20 years old?

• 0 - 2 → WHO

• 2 - 5 → CDC

• 5 - 20 → CDC

Which growth chart (CDC vs WHO) are used in other countries for one that is 0-2 years old? 2-5 years old? 5-20 years old?

• 0 - 2 → WHO

• 2 - 5 → WHO

• 5 - 20 → varies (some have country specific charts whereas some continue to use WHO charts made for 5-18 year olds)

What is the CDC Extended BMI-for-age growth chart?

a different BMI-for-age growth chart that extends farther than the 97th percentile to allow for the close monitoring of obesity as the obesity prevalance had increased since 1980 (when the first chart was made)

What indicator and cutoffs are needed to interpret someone as underweight?

indicator: weight for age

cutoff: < 3rd percentile

What indicator and cutoffs are needed to interpret someone as having stunted growth?

indicator: height/length-for-age

cutoff: < 3rd percentile

What indicator and cutoff is needed to interpret children 0-2 years old as wasting?

indicator: weight-for-height/length

cutoff: < 3rd percentile

What indicator and cutoff is needed to interpret children 2-20 years old as being overweight?

indicator: BMI for age

cutoff: ≥ 85 and < 95th percentile

What indicator and cutoff is needed to interpret children 2-20 year old as being obese?

indicator: BMI for age

cutoff: ≥ 95th percentile

What is the distinction between size and growth?

• attained size: product of prior nutritional experience and not reflect recent events as it is a static measurement

• growth: changes in body size during an interval of time and thus reflects nutritional conditions during that time as it is a dynamic measurement

Is growth or size a more sensitive indicator of recent nutritional status?

growth

What is growth velocity?

change in weight or height per unit time

How would you interpret growth velocity on a growth chart?

if it tracks on one of the percentiles then that is typical, anything that deviates/crosses percentile lines will be considered deviating from the norm

How do you calculate the z-score? In terms of anthropometry, what is it used for?

(actual value - expected value aka the mean)/SD

• tells us the number of standard deviations below or above the reference median

What indicator and z-score cutoff would consider one underweight?

• indicator: weight for age

• cutoff: z score < -2

What indicator and z-score cutoff would consider someone stunting?

• indicator: length for age

• cutoff: z score < -2

height for age z-score = HAZ

What is a common way to assess childhood malnutrition?

height for age

• low HAZ indicates that a child has failed to reach their growth potential

What is a particular trend that we are seeing in regard to height for age z-score (HAZ)?

at the population level, there have been HAZ declines from birth to 24 months in many low income countries (Latin America, Sub-Saharan Africa, Asia)

What indicator and z-score cutoff would consider someone as stunting?

• indicator: weight for length

• cutoff: z score < -2

What are the mid-upper arm circumference cutoffs to consider < or equal to 5 year olds normal, moderate wasting, and severe wasting?

• normal = > 12.5 cm

• moderate wasting = 11.5 - 12.5

• severe wasting = < 11.5

Rank the relative sensitivity of six anthropometric indicators to acute change in nutritional status.

MOST SENSITIVE

1. weight velocity

2. weight for length

3. arm circumference

4. skin-fold thickness

5. weight for age

6. length for age

What are two clinical diseases related to severe malnutrition?

1. marasmus

2. kwashiorkor

What is marasmus?

protein and energy deficiency

• symptoms include protruding bones, ribs, spine, and loose baggy skin

What is kwashiorkor?

protein deficiency

• symptoms include bilateral pitting edema, protruded belly, scaly skin, thin or brittle reddish hair, loss of hair, loss of appetite, and irritability

Children with severe wasting have how much higher risk of death comapared to children of normal weight for length?

11.6 times higher risk

• most risk is due to deaths from infectious causes such as respiratory infections or diarrhea

What are three indicators of acute malnutrition?

1. weight for height z-score < -3 (severe wasting)

2. MUAC < 11.5 cm (severe wasting)

3. bilateral edema

presence of any one of these signs in a child is an indication that urgent action is needed

What factors are leading to marasmus or kwashiorkor?

• acute food shortage (famine, extreme drought, sever food insecurity)

• persistent or sever diarrhea

• infections or chronic diseases (HIV, tuberculosis, cancer)

Overall, is there any global improvement in terms of stunting, wasting, and overweight people?

• amount of those wasting and or stunting have decreased

• overweight percentages are increasing globally