EL ORDEN, GEOMETRÍA Y SIMPLICIDAD

Nutritional assessment or assessment of nutritional status is a process of estimating changes in body’s nutritional composition.

Apart from its declaration of the fitness of the population, it is invaluable in predicting risk for surgery and other stressful therapeutic activities.

Clinical examination, anthropometric measurements and biochemical estimations are frequently used in assessing the nutritional status of a child⁷⁸. Anthropometry has proved to be the cheapest and simplest method when compared to others⁷⁸. Measurements must be related to those expected from a standard population⁷⁷.

Anthropometric Method

This is the measurement of certain parameters of the human body and it is the most frequently used tool in public health evaluation and in the clinical settings. It involves measurements of weight and height based indices, circumferences and skinfold thickness.⁷⁹

Weight for Age

It is the simplest of anthropometric measurement and

weighed lightly clothed on beam balances or weighing scales. The values are compared with accepted standard if the age of the child is known. A weight for age is a measure of undernutrition. A child is underweight if the weight is less than 80% of the standard.

Length or Height for Age

Children with reduced length or height for age are described as stunted. Height for age less than 90% of the standard is considered as significant stunting and a height for age less than 85% of the standard as severe stunting. Sophisticated infant measurement tables and stadiometers are available but much can be achieved with head and foot boards set at right angles to horizontal or vertical planes with accurate steel tapes used for the measurement⁷⁷.

Weight for Height

This is an important indicator of recent or current nutritional status. Children with reduced weight for height are described as wasted. A weight for height of <80% of the standard is considered as wasting and less than 70% as severe wasting. The weight of the child is compared with weight of reference children of the same height.

Mid Upper Arm Circumference

This assesses muscle bulk by measuring the part of the arm whose circumference varies little between ages 1 and 5 years but which wastes rapidly with malnutrition⁸⁰. It is widely used in community screening because it saves time. Shakir’s tape⁸¹ to distinguish marginal and definitely abnormal values is used for this purpose.

Skinfold thickness

Skinfold caliper such as Harpenden or Lange calipers are used to measure the thickness of skin and subcutaneous fat where fat folds can be raised⁸². Classical sites are triceps, biceps, subscapular, abdominal or suprailiac sites. It is judged by reference to centile charts (only triceps and subscapular charts are available).

Body Mass Index (BMI) or Quetelet’s Index (W/H²)

It is mainly used to assess nutritional status of older children and adults. It is calculated by dividing the weight of the child in kilogrammes (W) with the square of the height in metres (H²).

Other parameters include chest circumference and chest circumference- head circumference ratio.

Nutritional Assessment in Developing Countries

Most researchers in developing countries have found the use of anthropometric method suitable in assessing the nutritional status of their subjects. Osisanya et al⁸³, Adekunle⁸⁴ and Esimai et al⁸⁵ in Southwestern Nigeria, Ogechi et al⁸⁶ and Nwokoro et al⁸⁷ in Southeastern Nigeria, Okolo et al⁸⁸ in Northern Nigeria as well as Macharia et al⁸⁹ and Friedman et al⁹⁰ in Kenya employed the effectiveness and simplicity of anthropometric parameters mostly in combinations (height, weight, mid upper arm circumference, skinfold thickness) to determine patients’ nutritional status. Non-invasiveness, cost efficiency, coverage of large population with ease and simple technology are some of the highlighted benefits. For the purpose of this study, anthropometric method will be equally used.

Z- SCORE

Many Reference International Standards for growth have been recommended over the years for example the Harvard and London standards⁹¹. The Havard standards were drawn up by the Havard School of Public Health and based on data collected from children of North European stock in Boston in the 1960s. This was not

selected population. The sample population for the London standards was however taken at random from the London schools in the 1960s and was very extensive. The standards are also not internationally representative. The most widely accepted reference at the present time is that developed by the National Center for Health Statistics (NCHS) in the United States⁸⁰. It was adopted by WHO and has been recommended for International use^79,80.

Mild malnutrition refers to nutrition parameters equal to or below minus one standard deviation (-1SD) from the median of the NCHS standards⁹². A child is moderately malnourished when the parameters are equal to or below minus two SD(-2SD) from the median of the NCHS standards while severe malnutrition is when it is equal to or below minus 3 from the median of the NCHS standards⁹². Normal nutrition is therefore within one standard deviation of the median of the NCHS standards.

Nutrition parameters assessed using the NCHS includes the weight for age Z score (WAZ) which measures degrees of underweight, height for age Z score (HAZ) which measures degree of stunting and weight for Height Z score (WHZ) which measures degree of wasting. Others are the mid-upper arm circumference for

age Z-score, occipitofrontal circumference for age Z-score, and triceps skin fold thickness for age Z score ⁷⁹.

Clinical assessment

This is mostly useful in specific nutritional deficiencies.

Energy and protein deficiencies however tend to be reflected in poor growth, low weight, and loss of fat and muscles. Signs of malnutrition may not be specific, that is, they may be related to non-nutritional factors such as poor hygiene or excessive exposure to the sun particularly in the caucasians. These signs may not correlate with dietary intake data or the biochemical values in the individual or the population. Health workers participating in clincal evaluation of malnutrition should note that various signs have different degrees of reliability. The age of the person being examined also plays a role in the way the signs present themselves and in the interpretation of the signs. For example Scurvy presents in the child as painful swollen joints and gingival bleeding while in the elderly it appears as a small black and blue marks which very often appear on the skin over the medial aspect of the leg. Any physical findings that suggest a nutritional abnormality should be considered a clue rather than a diagnosis.

Biochemical assessment

Estimates of body constituents particularly plasma protein and certain enzymes e.g transferrin are helpful although blood levels do not always reflect body reserves accurately. Assessment of tissue content and store may be more accurate but less practical.

Greater interference, more refined technology and staff training are required in contrast to anthropometric or clinical nutritional assessment⁷⁷. While biochemical assessment of nutritional status is invaluable for completion, it may be an unaffordable luxury for large surveys, deprived communities or uncooperative subjects.