Anthropometry Assessment

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

Anthropometric measurements

Involves obtaining physical measurements of an individual or population groups, and comparing the measurements with references for interpretation and evaluation

Anthrop assessment

(T/F): Anthropometry is easy to conduct, since relatively unskilled personnel can be trained to perform the measurements

True

(T/F): Anthropometric assessment cannot be used to evaluate changes in nutritional status overtime

it can be used to provide historical information of nutritional status and evaluate changes over time

False

Limitations of anthropometric assessment (4)

Insensitive over short periods;

cannot detect specific deficiencies;

cannot differentiate changes as may be induced by specific nutrients;

can be affected by non-nutritional factors (reducing specificity and sensitivity)

Both random and systematic; may arise from the examiner’s inadequate training and from measurement difficulties, such as locating specific sites for skinfold thickness, and use of non-calibrated or defective instruments.

May be minimized by training personnel in using standardized techniques and calibrated instruments

Measurement errors

May lead to inaccurate measurements when composition and physical properties of certain tissues are altered

Alterations in the composition and physical properties of certain tissues

the assumption that thickness of subcutaenous adipose tissues indicates a constant proportion of total body fat and that an average thickness of subcutaneous tissue from a selected site is representative enough

Invalid assumptions about body composition

Sources of errors in anthropometry

1. Measurement errors
2. Alterations in composition and physical properties of certain tissues
3. Use of invalid assumptions about body composition

Methods to minimize errors in anthropometry

1. Training personnel
2. Using precise and calibrated instruments
3. Standardizing measurement techniques

An important screening procedure in detecting head and brain growth abnormalities among children up to 3 years old

Head circumference

An imaginary line passing through the external auditory meatus, which is the small flap of skin on the front edge of the ear and the top of the lower bone of the eye socket immediately under the eye

Frankfurt plane

Using a flexible non-stretch tape (0.6 cm in width) placed just above the supraorbital ridges, with the lower side positioned just above the eyebrows, ears, and around the back of the head; read to the nearest millimeter

Measurement of head circumference

Obtained with the subject lying down, in a supine or face-up position, and generally is reserved for children up to 24 months of age or for children who cannot stand erectly without assistance; index of chronic nutritional status 

Recumbent length

Measuring device with a stationary headboard and moveable footboard that are perpendicular to the backboard; measuring scale have its zero end at the edge of the headboard

Length board or infantometer

Composed of the skull, spine, pelvis, and legs; can be measured for subjects 2 to 3 years of age and older who are cooperative and able to stand without assistance. Read to the nearest 0.1 cm

Stature or standing height

A measurement error that occurs when an observer's eye is not properly aligned with the measuring scale, causing the reading to appear displaced from its true position

Parallax error

Measurement equipment for height

Stadiometer, height board, or microtoise

An alternative way of measuring height, which is correlated with stature

Knee height

An instrument developed by Valk consisting of a movable chair with an adjustable height; enables the distance between the heel and knee of the right leg (also called the lower leg length) of a sitting child aged more than three years, to be estimated with a technical error of measurement of 0.16 mm

Knemometer

Designed to measure the short-term growth of the lower leg; measurements are taken and recorded electronically while sitting; used for children 3 years and above

portable knee height measuring device

The distance between the heel and knee of the right leg; the maximum distance that can be reached during the movements of the child’s knee

Lower leg length

Hand-held knemometer used to measure short-term changes in an infant’s lower leg length. The device has an electronic slide that discriminates very narrow intervals, such as in periods of slow then accelerated growth.

Mini-knemometry

Consists of an adjustable measuring stick with a blade attached to each end at a 90^o angle. This device is most useful among adults who are unable to stand, with severe spinal curvature or other skeletal deformities.

Knee height caliper

Knee height measurements are obtained from which leg.

This side was used by researchers in developing equations for estimating statures from knee height

Left leg

An alternative measurement to height; correlated with stature; most useful when assessing retrospective stature at young adulthood prior to age-associated loss in stature

With arms kept at shoulder height, take measurement when the tip of the middle finger of the right hand is in contact with the fixed marker board, while the middle finger of the left hand is in contact with the movable board; read to the nearest 0.1 cm

Arm span

Represents the sum total of the four chemical compartments of the body, namely, muscle protein or fat free mass, fat, water, and bone mineral mass.

An important variable in equations predicting caloric expenditure and in indices of body composition

Body weight

Commonly used for measuring weight of children less than two years of age

With minimum clothing, the child is slipped into the sling. The reading is made as soon as the indicator on the scale stabilizes.

Suspended scale with a weighing sling (Salter scale)

What if a child aged >2 year was measured by length instead of height?

Correction factor needed since according to the WHO CGS: children <24 months - length-based indicators, children >24 months - height-based indicator

Use a correction factor of 0.7 cm which will be deducted from length to obtain height

An alternative to the suspended scale. The infant is placed on the pan, ensuring that the weight is equally distributed; weight is recorded to the nearest 10 grams (0.01 kg)

Pediatric scale with a pan

The more accurate and reliable equipment for older children and adults, with electronic scales as its alternative; weight is recorded to the nearest 100 g (0.1 kg)

Beam balance

Less reliable because of inconsistent results after repeated use

Spring balance scales (ex. bathroom weighing scales)

Less affected by adiposity; highy associated with lean body mass and muscle size; measured using caliper blades as the distance between the epicondyles of the humerus and read to the nearest millimeter.

a measure of frame size

Elbow breadth

Comprises the skeletal muscle, non-skeletal muscle, soft lean tissues, and the skeleton

Fat-free mas

The main storage form of energy in the body that provides estimates of energy balance

Fat

Indicates protein reserves

Body muscle

Optimal body fat content in men

12-20% (ave. 14.7%)

Optimal body fat in women

20-30% (ave. 26.9%)

Found in the bone marrow, central nervous system, mammary glands, and other organs; 9-12% of body weight among women; 3% among men

Essential fatty acids

Consists of inter- and intramuscular fat, fat around organs, GI tract, and subcutaneous fat; arond 15% among women and 12% among men

Stored fat

Estimated to be 1/3 of total body fat in both men and women

Subcutaneous fat

Provides an estimate of total body fat; measured by skinfold thickness

Subcutaneous fat

Measuring equipment for subcutaneous fat

Precision thickness calipers (Harpenden, Lange, Holtain

Measured in the midpoint of the back of the upper arm, between the acromion process and the tip of the olecranon; most frequently used to obtain single indirect measure of body fat; representative of whole subcutaneous fat

Triceps skinfold

Measured by the thickness of a vertical fold on the front of the upper arm, above the center of the cubital fossa and at same level of the triceps skinfold; together with triceps, may assist in the calculation of muscle + bone cross sectional area; useful in obese, in whom other skinfolds cannot be measured

Biceps skinfold

Measured below and laterally to the angle of the shoulder blade, 45^o from horizontal, in the same direction as the inner border of the scapula; subcutaneous tissue on the posterior aspect of the torso; may predict total body fat, blood pressure, and blood lipids

Subscapular skinfold

Measured along the midaxillary line immediately superior to the iliac crest; useful indicator of subcutaneous adipose tissue distribution, which is important in regard to risk of disease

Suprailiac skinfold

Which side of the body should be measured for skinfold thickness

No universal rule, but current practice is right side

Assumptions in the estimation of total body fat using skinfold thickness

"1. Thickness of subcutaneous fat reflects a constant proportion of total body fat
2. The sites represent the average thickness of subcutaenous fat
3. Age and disease state - probable shift of fat storage from subcutaneous to deep visceral sites in malnourished

The ratio derived from dividing the waist circumference by the hip circumference; a method for distinguishing fatness in the lower trunk and in the upper trunk; known to correlate with total body fat mass, mainly assessing subcutaneous and visceral fat depots

Waist-to-hip ratio (WHR)

Lower WHR or lower trunk fatness

Gynoid obesity

upper trunk fatness or higher WHR

Android obesity

Measured from the widest point over the buttocks

Hip circumference

Measured at the mid-way between the tenth rib and the iliac crest; or at the umbilicus level

Waist circumference

A better correlate of intra-abdominal fat (visceral fat) and/or total fat

Waist circum

A calculated area, derived from skinfold thickness and limb circumference measurements; correlates with total body fat, in view of recognition that more fat is needed to cover a large limb than to cover a smaller limb.

Subcutaneous fat may not always be evenly distributed around the limbs"

Limb fat area

A mixture of water, minerals and protein

Fat-free mass

provides an index of body protein reserves

Muscle mass

Correlate with measures of total muscle mass; used to predict changes in protein reserves

Can change with age and disease conditions; cannot provide direct measures of body protein nor detect small changes

Mid-upper-arm muscle circumference + mid-upper-arm muscle area

Useful in diagnosing protein-energy malnutrition

Used when the amount of subcutaneous fat is small because MUAC = subcutaneous fat + muscle

Mid-upper-arm Circumference (MUAC)

The calculated circumference of the inner circle of muscle surrounding a small central core of bone; derived from MUAC and tricep skinfold thickness; used to assess total body muscle mass

Cannot detect small changes in muscle mass

Mid-upper-arm Muscle Circumference (MUAMC)

Reflects the true magnitude of muscle tissue change; an index of total body muscle mass

Mid-upper-arm Muscle Area (MUAMA)

Cut-off point of acute malnutrition among 6 months to 5 years old children

<12.5 cm

Formula for MUAMC

MUAC - (pi)(TSK)

Useful in interpreting anthropometric measurements; constructed and compared with reference values or standards

Anthropometric indices

Anthropometric index in relation to age (e.g. weight-for-age and height-for-age)

Single raw measurement

Example is weight-for-height, which measures wasting and is sensitive to current nutritional status

Combination of two measurements

Example is BMI and WHR

Simple numerical ratios

Also known as Quetelet's index; useful in indicating body fatness or adiposity

Body mass index (BMI)

Obtained by dividing waist circumference (at the narrowest point)  by the hip circumference (at the widest point); an index of abdominal fat distribution; describe the distribution of both subcutaneous and intra-abdominal adipose tissue 

Waist-to-hip ratio (WHR)

The distribution of a population derived from a large representative sample of a population, which is reasonably healthy and well-nourished, against which indices are compared

Reference data

Combinations of measurements such as weight-for-age, weight-for-height, and height-for-age, among others

Indices

An index of chronic protein-energy malnutrition during the first two years of life

Beyond two years, growth in the head area may be so slow that this index no longer becomes useful in detecting changes

Head circumference-for-age

This is an index of acute malnutrition, and is largely used in protein-energy malnutrition and overnutrition

Cannot reflect wasting since it does not take into account the individual's height

Weight-for-age

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

Weight-for-height or weight-for-length

Indicates the degree of linear growth, which tells of past nutritional history or stunting

Height-for-age

Also known as Quetelet’s Index; measures body weight corrected for height; a sensitive index of current nutritional status, but cannot distinguish between excessive weight due to adiposity, muscularity or edema

Weight-for-height or Body Mass Index

The position of the measurement value in relation to all the measurements when ranked in the order of magnitude; rank position of an individual relative to a reference population

Normal distribution: 50th percentile = mean and median 
Skewed distribution: 50th percentile = median"

Percentile

Measures of the deviation of the anthropometric value from the reference mean or median in terms of standard deviations

(observe value - median reference value) / SD

Z-scores

Ratio of a measured anthropometric value such as weight of an individual, to the median value of the reference data for the same age or height, expressed as percentage; useful when the distribution around the median value is unknown, or the distribution of the data is not normalized

Percent of median

Uses of anthropometric indices in clinical settings

Screening for abnormal changes and assessing response to therapy  of individuals

Uses of anthropometric indices in public health

Identifying populations at risk to malnutrition

Act of checking and adjusting the weighing scale within the possible and allowable error; important to ensure that scale is within tolerable limits of accuracy and to detect deterioration beyond the tolerable levels

Calibration

Process of always keeping the weighing scale in good operating conditions through simple housekeeping measures, lubrication, corrosion control, servicing, repair storage and handling, and record keeping

Maintenance

The process of hanging the scale, attaching empty weighing pants, and adjusting the scale to zero

Zero-ing (tare)

Assessment of body composition by measuring the density of the entire body; expressed as mass per unit volume and usually is obtained through hydrostatic/underwater weighing or air-displace­ment/water-displace­ment pleth­ysmog­raphy

Densitometry

picked up horizon­tally on the mid­axillary line, at the level of the xiphoid process.

Midaxillary skinfold

Designed to exert a defined and constant pressure throughout the range of meas­ured skin­folds and to have a standard contact surface area or “pinch” area of 20‑40mm²

Precision calipers

Considered the gold standard criterion method for mea­sur­ing per­cen­tage body fat because the tech­nique reduces the need for theo­ret­ical assump­tions when calcul­ating body compo­sition outputs; information on body weight, body volume, total body water (TBW) and bone mineral mass are each collected separate

2-component model: fat-free mass and fat mass"

4-component model

The calculated cross-sectional area of arm fat, derived from skin­fold thick­ness and arm cir­cum­fer­ence meas­ure­ments; used as an index of total body fat especially in emergency settings

Arm-fat area

WHR cut-off points for men and women

>0.9 and >0.85 = abdominal obesity

Cut-off points for waist circumference among asians

>90 cm for men; >80 cm for women

Cut-off points for waist circumference among male and females (according to WHO)

Male:  >94 cm (increased) >102 cm (substantially increased)

Female: >80 cm (increased) >88 cm (substantially increased risk)

The WHO Multicenter Growth Reference Study MUAC and skinfold measurements were taken on which side of the body

Left

Cut-off for MUAC

<125 mm = acute malnutrition; <115 = SAM - for 6-59 months

The gold standard methods for in vivo assessment of muscle mass

Magnetic resonance imaging (MRI) and computer tomography (CT)

Often used as a surrogate marker of skel­etal muscle mass; has the added advantage of having a lower fat mass compared to other body sites; used to diagnose sarcopenia (low muscle mass and low muscle strength)

Calf circumference

Cut off points for calf circumference (Asian Working Group for Sarcopenia)

< 34 cm for males; < 33 cm for females

Recommended tech­nique for mea­sur­ing muscle strength; simplest and most inexpensive method; also a measure of physical fitness in children and athletes

Hand grip strength

Measurement equipment of hand grip strength; the gold standard equipment

Hydraulic hand dynamo­meter Jamar