List the different methods used for assessment of nutritional status. How are anthropometric measurements used in the assessment of nutritional status?
The different methods used for the assessment of nutritional status are-
i) Anthropometric measurement.
ii) Clinical method
iii) Diet survey
iv) Biochemical assessment.
Anthropometric measurements used in the assessment of nutritional status:
Anthropometric measures simply refer to the measurements of body size. The four most commonly used & simply body measurements are:
i) Weight for age
ii) Height for age
iii) Arm circumference for age
iv) Weight for height
v) Other anthropometric measures.
i) Weight for age:
Weight for age is a commonly used indicator of body size & it reflects the level of food intake. The relative change in weight with age is more rapid than that is height & is much more sensitive to changes in the growth pattern of the individual. Significant changes can be observed over periods of a few days. Weight for age is very sensitive measure short duration malnutrition. The weight of children should be recorded regularly to check if there is a regular gain in weight. Then the weight recorded can be compared with standard values.
ii) Height for age:
Length or height is a very reliable measure that reflects the total increase in size of individual up to the moment it is determined. For example, we know that normally a body measures 50 cm at birth. This birth length increased to 75 cm at one year of age. By the age of four years, the child is 100 cm tall. There often the child gains about 5 cm in height every year, until the age of 10 years. Therefore the recording height would help us to know whether the child is growing normally & is in good health or not. But it is also important that height changes too slowly to be used by itself detect changes in growth patterns within a short time interval. In other terms height for age is only a measure of long duration malnutrition.
iii) Mid-upper arm circumference:
The mid-upper arm circumference is a useful indicator of nutritional status at individuals & communities. Arm circumference includes bone, fat & muscle. Fat & muscle are the body's energy & protein reserves. These reserves are reduced in the body if the body does not absorb or take enough food as appears in the case of protein-energy malnutrition thus resulting in reduced arm circumference. Arm circumference normally increases with age but between one to five years it does not change much & remains fairly constant. At this time the body fat is replaced by muscle.
iv) Weight for height:
By resetting the weight of a child to its height or length, an objective measure of the child's degree of thinness can be obtained. Weight for height basically is a very good index for short duration malnutrition. This measurement is of value especially in situations where child health services are not available to carry out periodic monitoring. The measure has an added advantage that accurate age assessment is not required & therefore it is age-independent & can be easily used in populations where the child's age is not known.
v) Other anthropometric measures:
Head & chest are the two other linear measurements which are used to study the growth pattern in children.
(a) Head circumference: The head circumference is mainly related to brain size. The infants have a large head at birth as compared to the rest of the body. The head circumferences increase rapidly during the first months after birth & thereafter it increases slowly. The brain size can vary with nutritional status. Therefore, the head circumference is a good indicator of nutritional status.
(b) Chest circumference: The chest circumference is also useful to detect malnutrition in children. A chest or head circumference ration is less than one taken between the age of six months & 5 years which is the indicator of malnutrition in children.