Prevalence of Nutritional Anemia in Infancy and Childhood with Emphasis on Developing Countries

Iron Nutrition in Infancy and Childhood, edited by A. Stekel. Nestle\ Vevey/Raven Press, New York © 1984. Prevalence of Nutritional Anemia in Infancy and Childhood with Emphasis on Developing Countries Rodolfo F. Florentine) and Romualda M. Guirriec Nutrition Center of the Philippines, Metro Manila, Makati, Philippines 3116 Even a rapid review of the literature reveals that millions of people around the world, especially in developing countries, suffer from nutritional anemia despite advances in detection as well as in methods of prevention and treatment. This high prevalence is due to multiple and complex factors that abound in developing countries. In these countries, there is a low standard of living with a high prevalence of malnutrition, poor environmental sanitation, high morbidity among children, and unequal distribution of wealth leading to extremes of wealth and poverty; all these conditions favor the onset of anemia. Although the major causes of nutritional anemia are, firstly, of dietary origin due to low intake and low bioavailability of iron and, secondly, due to blood loss caused by parasitism, these two factors are basically the result of interaction of other deep-seated factors linked to underde- velopment. It is imperative therefore that the causes of iron deficiency and of anemia be viewed beyond the immediate environment of the affected individual. The disease can be traced to its basic social, economic, and political environment. Figure 1 summarizes the underlying and immediate causes of iron deficiency. Not only is iron deficiency caused by a low amount of iron in the diet but also by its poor absorbability. The poor absorption of iron from cereal-vegetable-based diets is well known. Economic factors often limit the intake of meat and ascorbic- acid-rich foods that would enhance the absorption of iron. There are also socio- cultural practices that directly or indirectly affect dietary intake. Some religions prohibit the intake of certain meats. Preschool children, girls, and women are often at a disadvantage; cultural taboos and superstitious beliefs may prohibit the intake of certain foods at certain times, especially during infancy and childhood or during pregnancy and lactation. Parasitic infection is the second leading cause of iron deficiency anemia, and hookworm is the most notorious in this regard. Hookworm assumes greater signif- icance among older children, but fortunately not much in infants. Parasitic infection thrives in an unsanitary environment, and transmittal is enhanced by poor sanitary habits, inadequate health facilities, ignorance, poverty, and poor agricultural practices. The hidden losses become significant when iron stores are depleted because of increased physiological requirements, making infants and children particularly vul- 61 62 PREVALENCE IN DEVELOPING COUNTRIES UNDERLYING CAUSES IMMEDIATE CAUSES LOW FOOD SUPPLY ERRONEOUS FEEDING PRACTICES -INADEQUATE DIET - LOW SOCIOECONOMIC- STATUS LOW INTAKE OF- AVAILABLE IRON UNSUITABLE MEAL COMPOSITION -^POOR ABSORPTION- EXCESS OF INHIBITORS LACK OF ENHANCERS—I IRON DEFICIENCY GROWTH PREGNANCY & •*-INCREASED REQUIREMENTS- LACTATION — ACUTE BLEEDING CHRONIC BLOOD LOSS -BLOOD LOSS- •*• & PARASITISM L-POOR SANITATION- INADEQUATE HEALTH — -INFECTION- SERVICES FIG. 1. The development of iron deficiency. nerable. The iron requirements of infants and children, despite their much smaller body size, are almost as high or higher than those of the adult male. This situation is responsible for the high prevalence of nutritional anemia during infancy and childhood. DIAGNOSTIC PARAMETERS/PROCEDURES FOR ESTIMATING IRON DEFICIENCY Iron deficiency may be defined as a condition when the iron supply is inadequate for the normal synthesis of essential iron compounds (1). With the advancement of technology, new laboratory tests have become available; these have made possible a clearer definition of iron deficiency and a recognition of the limitations inherent in the traditional methods. The various tests have been thoroughly discussed, including their applications and limitations in several publications (2-6). Several factors influence the selection of diagnostic tests; it is important to realize that their usefulness for defining iron deficiency depends on the objectives for which they are being used. Thus nationwide surveys, for example, are designed to obtain data on prevalence and to identify populations at risk as targets of PREVALENCE IN DEVELOPING COUNTRIES 63 intervention strategies, whereas to a clinician the focus is on the individual diagnosis, therapy, and follow-up. One factor affecting the selection of a test procedure, especially among infants and young children, is the volume of the blood sample required and the manner in which it is obtained. With the exception of transferrin saturation, the various tests can be performed on a very small amount of blood that can easily be obtained by finger prick. The selection of tests will also depend on the equipment available and the level of expertise or training of laboratory technicians. The time required to obtain results of analysis is also a factor to consider. It should be pointed out that in most developing countries, where man- power and material resources are limited, the diagnostic tests generally used are the simplest and least expensive ones. Our present knowledge of the extent of iron deficiency has been dependent on the parameters used in laboratory diagnoses. Infants and children, however, pose certain problems in the use of such parameters. The laboratory diagnosis of iron deficiency in this age group, for example, requires the use of age-specific reference standards (5,6). There are marked developmental changes in normal values for hemoglobin, hematocrit, mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), erythrocyte protoporphyrin, serum ferritin, and transferrin saturation. Dallman (5) has discussed the "physiological anemia of infancy" wherein there is a decline in the concentration of hemoglobin during the first 2 months after birth from the highest to the lowest levels observed at any period of development. This is independent of nutritional factors and is primarily attributed to an abrupt decrease in erythropoiesis in response to increased postnatal delivery of oxygen to the tissues. Special attention must therefore be taken when interpreting data from infants and children. Ideally, reference standards for "normal" values should be obtained from healthy populations that have been screened to exclude individuals with mild iron or folate deficiencies or with conditions such as thalassemia minor. The nature of the population from which normative data are derived will greatly influence estimates of prevalence of iron deficiency, especially in infants and children (6). The parameters for the diagnosis of iron deficiency may be considered within the framework of the three stages occurring in its development. The first stage is the depletion of stored iron, and this is detected by the concentration of serum ferritin. The second stage involves transport of iron to the bone marrow, and deficiency is reflected in an increase in iron-binding capacity, decrease in transferrin saturation, decrease in serum iron, and increase in concentration of free erythrocyte protoporphyrin. The third stage is a decrease in erythropoiesis, resulting in a fall in hemoglobin and the presence of hypochromic microcytic red cells as reflected in a low hematocrit. Hemoglobin determination is the traditional method used for diagnosis, treatment, and follow-up of iron deficiency. Where the prevalence of iron deficiency is high, hemoglobin remains the best parameter for use in prevalence surveys. The concept of distribution analysis is very useful in public health practice (2,4). This is particularly helpful where prevalence is high. By comparing the proportions 64 PREVALENCE IN DEVELOPING COUNTRIES of the population below an arbitrary standard at different times, the changes in the severity of the anemia problem can be clearly seen. At any given point in time, however, the problem of what arbitrary standard to use becomes the issue. Marzan and Ibe (7), for example, using distribution analysis, proposed a value for the Philippines of 8.8 g% hemoglobin for children 1 to 3 years old as a cutoff point between "deficient-low" and "acceptable" levels, and corresponding values of 10.5 and 10.8 g% for children 4 to 6 and 7 to 9 years, respectively. These values are somewhat different from those recommended by the World Health Organization. In any event, such standards or cutoff points are, by their nature, arbitrary because they depend on the objectives for which they have been set. In the planning of public health interventions, for example, one not only considers the number of iron responders vis-a-vis nonresponders that would be below the cutoff point, but also the logistical constraints and available resources for such interventions. Since estimates of prevalence have critical implications on public health pro- grams, they should ideally be determined through appropriate surveys with three important considerations: (a) well-defined criteria for diagnosis, (b) well-defined "normal" values, and (c) adequate representativeness of the population. Although this is hypothetically possible, most of the prevalence studies done so far have been conducted on the segment of the population most at risk from nutritional anemia. In practice also, data are obtained from infants and young children admitted

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