For the assessment of nutritional status and growth, anthropometric indices are often used. While selecting an appropriate index for nutritional assessment, the following two considerations are made. Firstly, the index selected must fit the objective to be achieved ensuring that right measure is taken secondly, the index interpretation will rely heavily on the fact that whether the assessment is made for population or individual diagnosis.
These considerations will have serious implication foe the program planning .In children anthropometric indices are mostly used to asses the growth, nutritional status as well as nutritional imbalance that are a consequence of under and over-nutrition . However, growth and development of children is considered as an important indicator of nutritional status and over all health and wellbeing of populations. The indicator of children growth and nutrition are as follow:
BMI-for -age
Height- for- age
Weight- for - age
Weight - for length
BMI- for- age:
BMI differently used for children to classify their nutritional status. It is calculated in a manner similar to adult and subsequently compared to the typical values for reference children of the same age.
In children BMI is compared to reference value of children percentile of the same age and sex instead of comparison against fixed threshold for overweight and underweight. BMI - for -age can be used in children aged 2-20 years.
BMI Classification
less than or equal to 95 percentile Obese
85 to < 95 percentile Overweight
5 to < 85 percentile Healthy weight
< 5 percentile Underweight
Height - for -age:
Small height- for -age (stunning), is generally of poor growth or growth retardation, and outcome of frequent infections, poor diet and mortality and morbidity. Long term deprivation of good nutrition particularly during first 1000days starting from conception to second birth day of the child result in stunning that often lead to delayed mental development, reduced intellectual capacity and poor school performance.
This can directly affect the economic productivity of a country. Stunned female child develops in to stunted adult and is at a greater risk for obstetric complications due to a smaller pelvis, delivering a low birth weight infant. This will continue an intergenerational cycle growth of infant results in smal Length Desired growth indicator
In first year 50% increase in birth length
2nd year 12cm increase
By 4th year Double the birth length
From 2 year to adolescence 5cm increase per year
Weight for age:
Weight for age is the simplest of measure and serves as indicator of various health problems. It is suggested that there is slightly higher risk of mortality for mildly underweight children and it increase with the severity of underweight. Contrarily it is believed that childhood adiposity is linked with higher incidence of adulthood obesity, increasing the risk of various chronic diseases, such as CVD's and diabetes. Obese children and adolescence are most likely to long term and short term health consequences:
- CVD's
- Diabetes
- Musculo-skeletal disorder/ osteoarthritis
- Endometrium, colon and breast cancer
System for the interpretation of nutritional status:
For the assessment of the child, s nutritional status and designate whether he/ she is well nourished or under nourished, it had to be compared with a ''reference '' child of the same sex and age. Choice of a growth reference population is a key consideration and received considerable attention in the last decades.
The z-score ;
I tis known as one of the best system for interpretation and presentation of anthropometric data mainly for population - based nutritional assessment tools e.g surveys and nutritional surveillance. This classification system is relatively advantageous over other method deviations or Z score below or above the median value or reference mean.
Calculation of Z- score
According to WHO, following is the calculation of the Z-score:
Z-score=(X-m) /SD or
Z- score(or - score)=(observed value (height, weight or BMI)- median value of the reference population )/ standard deviation of reference population
Example:
weight - for -age z score
Z-score is a measure of ''how many standard deviation a measured oe observed value is away from mean of reference population. In the formula X represents the observe value, For Example if 1you want to find the z score of weight (8.13) of 12-month-old child, put 8.13 as X in the equation.
Likewise, m in the equation is the mean or median weight obtained from the reference population of same age . If we assure that median weight of the reference population was 9.8 kg, we will put 9.6 in place of m In the next step, we would find the standard deviation of the reference population .
Standard deviation is an indicator of the spread of values among the reference population . Standard deviation is calculated from the mean or mathematical average.
Z score Interpretation
>-1 Normal Not underweight, stunted,
-2 t0 -1 mild Wasted
-3 to -2 moderate Underweight, stunted,
wasted
<-3 severe
percentile
''A percentile is a measure in statistic indicating the value below which a given percentage of observation in a group of observations fall.'' It ranks the position of an individual on a reference distribution . For example: For a child of known age and sex whom BMI falls on the 85th percentile line, has a BMI the same or more than 85% of the reference population children of the same age and sex. For tracking the proper growth and development of the children , growth chart are useful tool.
These growth height, weight and head circumference at a rate is characteristic for his/her age. By charting a child, s pounds/kg, inch, and head size over time, these measurement allow to observe whether a child is gaining weight more rapidly than adding inch,
What are common anthropometric measurement?
What are anthropometric indices?
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