Assessment of Nutritional Status PDF

UNIT 25 ASSESSMENT OF NUTRITIONAL STATUS Structure 25.1 Introduction 25.2 Methods of Assessing Nutritional Status 25.2.1 Anthropometric measurements 25.2.2 Clinical Method 25.2.3 BiochemicalAnalysis 25.2.4 Diet Survey 25.3 Growth Monitoring 25.4 Le...

UNIT 25 ASSESSMENT OF NUTRITIONAL STATUS Structure 25.1 Introduction 25.2 Methods of Assessing Nutritional Status 25.2.1 Anthropometric measurements 25.2.2 Clinical Method 25.2.3 BiochemicalAnalysis 25.2.4 Diet Survey 25.3 Growth Monitoring 25.4 Let Us Sum Up 25.5 Glossary 25.6 Answers to Check Your Progress Exercises 25.1 INTRODUCTION Health and nutritional status of an individual depends on the food he eats. This is a fact and it must be evident to you from the study of nutrition so far. Another aspect that is crucial and should be of interest to us all is - how to find out whether the individual is in a state of good nutrition or not? You may recall reading about the good signs of health in Unit 1, Block 1. Examination or appraisal of the individual according to these signs could be one way of assessing the nutritional status. What are the others? Collecting food intake data of individuals could be the other. Sometimes, you may remember being asked by your doctor to get your blood or urine sample examined for specific diagnosis. For example measuring the level of Haemoglobin (Hh) in the blood or measuring the level of glucose in the urine. These tests also constitute the assessment of nutritional status. How? In this unit we will learn about the various different methods and their application in assessing nutritional status of an individual or group of individuals in the community. How to measure growth (since growth is a measure of nutritional status)? What are the specific signs and symptoms one should look for during assessment? How does measuring the constituents of body fluids (i.e. blood, urine) help in assessing nutritional status? How to collect food intake data? These are the other set of questions which this unit attempts to answer. Objectives After studying this unit, you will be able to: describe the methods used in assessment of nutritional status and a discuss the relative significance of each method used. 25.2 METHODS OF ASSESSING NUTRITIONAL STATUS How do we determine the nutritional status of individuals? Before we discuss the techniques, let us quickly recall the meaning of nutritional status. Nutritional status, we know,refers to the state o f health of an individual as it is affected by the intake and utilisation of nutrients. From this definition, it seems that evaluation of nutrient intake alone can help judge the nutritional status of individuals. Would you agree? Well, it is not all that simple. Consider the example of a child who is not growing adequately. The child's failure lo achieve an adequate rate of growth, for instance, may be caused due to heredity factors, infectionslother diseases, dietary lack or any other factor. Hence, evaluating the food intake alone may not give sufficient evidence for judging the nutritional status. What might be helpful would be to put together information about the type of illness, if any, including the observable signs of ill health the child is suffering from; the level of nutrients and other substances in the blood and urine. This information you would notice would help confirm whether the growth failure is caused by inadequate nutrient intake or some other factor. Examining the child's food intake pattern, for example, may suggest the existence of  nutritional deficiency but mzasuring the particular nutrient (or ~ t compounds) s concentration in the bloodluiine may confirm the tentative diagnosis. Measuring the level of nutrients and other substances in the body fluid on one hand can indicate tissue depletion of nutrients before clinical signs are observable, on the other hand, a study of food intake pattern may strengthen the argument. I From our discussion above it is, therefore, evident that there is and can be no one simple procedure for assessing nutritional status. Because a particular finding may be due to any of the several causes, a variety of standard assessment techniques may be used to determine nutritional status. There are four major methods used to assess nutritional status of individuals and population groups which include. - Anthropometric measurement - Clinical method - Biochemical analysis - Diet survey What are these methods? What information do they provide? How and when to use these techniques in assessing nutritional status. These are some of the aspects discussed in the next section. Remember each of these methods has an unique contribution as well as inherent limitations that needs to be considered in the interpretation of data, but taken together they can confirm suspicions and provide factual basis for corrective measures. We begin the study of the techniques with anthropometric measurements. 25.2.1 Anthropometric Measurements 1I Anthrbpometric measures simply refer to the measurements of body size. You may recall reading earlier in Block 3 that measuring body weight and height provide useful data for analysing growth and for determining body size and composition. Growth as measured in terms of weight for age or height for age, reflects the sum total of what has occurred up to that point in time. Besides height and weight, measuring body circumference facilitates identification of the degree of body fat and the amount of lean body tissues i.e. muscles in the body. It aids in the identification of PEM and obesity. The four most commonly used and simple body measurements (which serve as good indicators of nutritional status), therefore, are : Weight for age Height for age ~rm'circumferencefor age Weight for height. This section presents a detailed study on these anthropometric measurements. A brief discussion on various other measurements (i.e. head circumference, chest circumference and skinfold thickness) is also presented in Highlight 5, which will give a complete picture of anthropometric measurements and their role in assessing nutritional status. Before we begin, we would like to draw your attention to the fact that the use of anthropometric measurements specially height and weight depends on two factors : 1) Accurate age assessment and 2) Appropriate normal values or standards for comparison. Accurate age assessment is necessary simply, because the body measures (i.e. height, weight, body circumference) increase with age. If the correct age is not known, it might not be possible to have an accurate assessment. Furthermore, the use of body measurements become useful only if, the actual measurements obtained on an individual are compared with known values or standards. What do we mean by standards? The average body measurements o f well-nourished and healthy children (belonging to the well-to-dosocieties) who are medically and socially well-protected are referred to as standards and these values are used for the purpose o f comparison. If the body measurements for age are comparable with those of well-to-do and healthy children, the child is considered nutritionally healthy. Tables providing standard measurement values of well nourished children are available. For example, Indian standards (data compiled by National Institute of Nutrition, NIN) and NCHS standards (USA). We will be using NCHS (National Centre for Health Statistics) standards for comparison, since studies conducted in India have shown that at least 30 until adolescence, the growth pattern of well-to-do Indian children is comparable with that of American children. Tables providing standard measurement values are given in Appendix 2 at the end of the block. With this knowledge let us begin our study of anthropometric measures. a) Height for age : Length or height is a very reliable measure t h lrflects~ the total increase in size of the individual up to the moment it is determined (and could indicate adequate nutritional status). For example, we know that normally 4 baby 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. Thereafter, the child gains about 5 cm in height every year, until the age of 10 years. Recording the height would, therefore, help us to know whether the child is growing normally and is in good health or not. But it is also important to note that height changes too slowly t o be used by itself to detect changes in growth pattern within a short time interval. In other terms, it is not a very sensitive measure for short duration malnutrition (i.e. the condition of the body resulting within a short time interval due to relative or absolute deficiency of one or m.ore essential nutrients). Furthermore, height does not decrease and, therefore, cannot indicate a deterioration in health. Height for age, therefore, is only a measure of long duration malnutrition (i.e. the condition resulting from a relative a r absolute deficiency of one or more nutrients over a very long period of time. LOW HEIGHT FOR AGE is indicative ofstunting and of chronic malnutrition. Next we come to the question how to measure height? A vertical measuring tape scale fixed on the wall can be used to record height of older children and adults as indicated in Figure 25.la. Alternatively height measurement can be taken against a wall (Figure 25.lb). The individual should stand with barefeet on a flat floor against a perpendicular wall with feet parallel and with heels, buttocks, shoulders and back of the head touching the wall. The head should be held erect and a mark should be made on the wall with a flat object touching the top of the head horizontally and its vertical edge flat against the wall. Height can then be measured using a good measuring tape. Fig. 25.1 Height Measurements In the case of infants, an infantometer (Fig. 2 5. 1 ~ can ) be used. This is a specially prepared wooden scale on which the infant is made to lie down, with the head touching the fixed head piece. The legs are extended fully by pressure on the knees and the movable sliding piece is allowed to touch the flat of the soles of the feet and the measurement is recorded. b) Weight for age : Weightfor age is-acommonly used indicator of body size, and it reflects the level of food intake. The relative change of weight with age is more rapid than that of height and is much more sensitive to changes in the growth pattern of the individual. Significant changes can be observed over periods of few days. Therefore, unlike height for age, weight for age is, a very sensitive measure of short duration malnutrition. The weight of children should be recorded regularly to check if there is regular gain in weight. The weight, recorded can then be compared with standard values or alternatively the weight can be plotted against age on a graph to see if the pattern of growth is normal (by comparing it with the normal curve). We will learn more about this aspect later i n this unit. A LOW WEIGHT FOR AGE is called UNDERWEIGHT. How do we measure weight? Weight can be measured with a beam balance (platform scale) as indicated in Figure 25.2a. More recently for weighing children salter scales (Fig. 25.2b) are being extensively used. The Salter scale can be hung from a roof or a tree as shown in the figure. The child is placed in the sling and then the weight is recorded. Fig. 25.2 Weight Measurements One can also use the ordinary weighing balance asshown in Figure 2 5. 2 ~to measure weight. But for measuring the weight of children using this balance we need to be more careful. First the weight of the mother and child together shobld be recorded and then the mother should be weighed alone. The difference in the two weights is the weight of the child. This measure, however, may not give very accurate results. So it should be used with caution. c) Weight for height :By relating 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 specially in situations where child health services are not available to carry out periodic monitoring and children are seen irregularly say once in a whlle. The measure has an added advantage that accurate age assessment is not required and, therefore, it is age-independent and can be easily used in populations where the child's age is not known. A too LOW WEIGHT FOR HEIGHT is called WASTING. Weight for height standards are available wh~chare given in Appendix 2 (Table IV) at the end of the block. d) Mid upper arm circumference (MUAC): l ' h ~mid upper arm circumference is an useful indicator of nutritional status of individuals and comhunities. How does this measure reflect the n u t r i t i o n a h m f individuals ts what we shall study first Arm circumference, you might be aware hasically includes bone, fat and muscle. Fat and muscle, you know, are the body's energy and 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 circrrmference normally increase with age, but between one to five years it does not change much and remains fairly constant. At this time the baby fat is replaced by ~nuscle.Measuring the arm circumference of this age group would, therefore, give a good idea whether the child is in good health or not. The mid arm circumference for age of well nourished Indian children is given in Table 111 in Appendix 2 at the end of the block.'^ measurement below 80per cent of the normal i.e.