STATUS OF IODINE NUTRITION IN CHILDREN (6-12 YEARS OLD) IN ABAKALIKI AND OHAOZARA LOCAL GOVERNMENT AREAS OF EBONYI STATE.

Transcription

1 1 STATUS OF IODINE NUTRITION IN CHILDREN (6-12 YEARS OLD) IN ABAKALIKI AND OHAOZARA LOCAL GOVERNMENT AREAS OF EBONYI STATE. BY ONYEKWELU KENECHUKWU CHIBUIKE PG/M.Sc./08/47648 DEPARTMENT OF MEDICAL BIOCHEMISTRY UNIVERSITY OF NIGERIA ENUGU CAMPUS JULY 2012

2 2 TITLE PAGE STATUS OF IODINE NUTRITION IN CHILDREN (6-12 YEARS OLD) IN ABAKALIKI AND OHAOZARA LOCAL GOVERNMENT AREAS OF EBONYI STATE. BY ONYEKWELU KENECHUKWU CHIBUIKE REG. NO PG/M.Sc./08/47648 A PROJECT SUBMITTED TO THE DEPARTMENT OF MEDICAL BIOCHEMISTRY, UNIVERSITY OF NIGERIA, ENUGU CAMPUS IN PARTIAL FULFILMENT OF THE REQUIREMENT FOR THE AWARD OF THE DEGREE OF MASTER OF SCIENCE (M.Sc.) IN MEDICAL BIOCHEMISTRY RESEARCH SUPERVISOR PROFESSOR I.E. EZEAGU JULY 2012 CERTIFICATION

3 3 This is to certify that Mr. Onyekwelu Kenechukwu Chibuike, a Post-graduate student in the Department of Medical Biochemistry, University of Nigeria, Enugu Campus has satisfactorily carried out this research work for the award of degree of Master of Science (M.Sc.) in Medical Biochemistry under my supervision. SUPERVISOR.. PROFESSOR. I.E. EZEAGU Date 2012

4 4 DEDICATION. This work is dedicated to my parents Sir and Lady M.C. Onyekwelu for their love and support.

5 5 ACKNOWDGEMENT My very sincere gratitude and appreciation are expressed to my supervisor, Prof. I.E Ezeagu for making available to me his expert knowledge and experience. I am also indebted to him for his patience, encouragement, accessibility and untiring effort in procuring materials for this study. My sincere thanks also to Prof. P.O.J Ogbunude, Prof. P.O Egwim, Mrs J.E. Ikekpeazu, Dr. C.O Ezeh, Mr. D.M. Ibegbu and Dr. E. Ejezie for their constant advice and criticisms. The entire staff of the Department of Medical Biochemistry are too numerous to mention individually but every one of them has contributed, in one way or the other to the success of this study. I so much appreciate UNICEF for supplying the iodized salt test kits used for this study. Finally, I am very grateful to my fellow Post-graduate students in the Department of Medical Biochemistry for their support.

6 6 ABSTRACT Iodine is essential for normal growth, brain development, cognitive ability and functioning of the body. On a worldwide basis, iodine deficiency is the single most important preventable cause of brain damage. Iodine deficiency has an immediate effect on child learning capacity, women s health, the quality of life in communities, and economic productivity. The study was to determine the iodine status of selected primary school children and household access to iodized salt and was carried out in Ohaozara and Abakaliki LGA s of Ebonyi state. Five schools were randomly selected from each LGA with 40 pupils from each school. A total of 400 pupils aged 6-12 years old were recruited for the study. Early morning casual urine samples were collected from the pupils using plastic bottles screwed with caps for the analysis of Urinary Iodine Concentration (UIC). UIC was estimated using the sensitive colorimetric method of Sandell- Kolthoff reaction after digesting the urine with ammonium persulfate as outlined by WHO/UNICEF/ICCIDD. The pupils who donated their urine were asked to collect about 2 teaspoons of salt (about 10g) from their family kitchen. The salts were tested on the spot using rapid iodized salt test kits. Analysis of the urine samples showed that the UIC for children in Abakaliki LGA ranged between 20 µg/l and 350 µg/l with160 µg/l as the median, while that of Ohaozara ranged between 15 µg/l and 380 µg/l with 140 µg/l as the median. The median UIC for the total study population was 145 µg/l. This result indicated iodine sufficiency according to the criteria of the WHO/ UNICEF/ICCIDD. Results of the household salt iodization testing showed that 90.0% of the total household salt samples collected during the survey proved iodized, only 63.5% were adequately iodized (>15ppm). The median iodine intake in the whole study population was at the recommended level ( µg/l), however, some groups had a low intake and may be prone to iodine deficiency disorder. Also some groups had high iodine intake (excess) and may be prone to iodine induced hyperthyroidism. The proportion of households consuming adequately iodized salt (63.5%) was below the recommended target of >90%. According to epidemiological criteria for assessing iodine nutrition based on median urinary iodine concentration of school-age children, the median urinary iodine concentration for the total children were in the adequate and within the optimal ( µg/l) range of iodine, strongly suggesting that iodine deficiency seems not to be a public health problem among the pupils in Abakaliki and Ohaozara LGAs.

7 7 TABLE OF CONTENT Contents Page Title Page i Certification ii Dedication iii Acknowledgement iv Abstract v Table of Contents vi List of Tables viii List of Figures ix CHAPTER ONE: INTRODUCTION Introduction 1 CHAPTER TWO: LITERATURE REVIEW 2.1 Iodine physiology Dietary sources Goitrogens Iodine Deficiency Disorder (IDD) Establishing Universal Salt Iodization (USI) in Nigeria Specific Iodine Deficiency Disorder Effects of iodine deficiency through the life cycle Nutritional status and goiter Thyroid hormones Metabolic effects of thyroid hormones 12

8 Treatment and prevention Increasing Iodine intakes in population and iodine excess Side effects of iodine supplementation 15 CHAPTER THREE: MATERIALS AND METHODS 3.1 Experimental design Qualitative determination of dietary iodine Quantitative determination of dietary iodine Calculation of result 20 CHAPTER FOUR: RESULTS 4.1 Urinary iodine concentration Household salt iodine testing 24 CHAPTER FIVE: DISCUSSION 5.1 Assessment of urinary iodine status Monitoring salt at the household level 31 Conclusion 34 Recommendation 34 References 35 APPENDIX 41

9 9 LIST OF TABLES Table Page Table 4.1 Result of urinary iodine analysis: Abakaliki L.G.A. (n=199) 21 Table 4.2 Result of urinary iodine analysis: Ohaozara L.G.A. (n=199) 22 Table 4.3 Result of urinary iodine analysis: Total study population (n=398) 23 Table 4.4 Summary of urinary iodine concentration (µg/l) 24 Table 4.5 Result of household salt iodization & testing: Abakaliki L.G.A (n = 200) 24 Table 4.6 Result of household salt iodization & testing: Ohaozara L.G.A (n = 200) 25 Table 4.7 Result of household salt iodization & and testing: Total study population ( n = 400) 26

10 10 LIST OF FIGURES Figure Page Fig 4.1 % Household access to Iodized salt 27 Fig 4.2 Comparism of Universal Salt Iodization (USI) assessments in Nigeria 28 CHAPTER ONE INTRODUCTION. Iodine is an essential component of the thyroid hormones, thyroxine (T 4 ) and triiodothyronine (T 3 ). They regulate many key biochemical reactions, especially protein synthesis and enzymatic activity. Major target organs are the developing brain, muscle, heart, pituitary, and kidney. Thyroid hormones, and therefore iodine, are essential for mammalian life (Daryl and Granner, 2000).

11 11 Iodine was found in the thyroid gland by Baumann (1896). Marine & Kimball (1917) showed that thyroid enlargement (goiter) was caused by iodine deficiency and could be prevented by iodine supplementation. Goiter prophylaxis through salt iodization was first introduced in Switzerland and the United States in the early 1920s. In 1980, the World Health Organization (WHO) estimated that 20 60% of the world s population was iodine deficient and/or goitrous, with most of the burden in developing countries. Controlled studies in iodine-deficient regions showed that iodine supplementation not only eliminated new cases of cretinism but also reduced infant mortality and improved cognitive function in the rest of the population (Hetzel, 1983). Iodine deficiency has multiple adverse effects on growth and development in animals and humans. These are collectively termed the iodine deficiency disorders (IDDs) and are one of the most important and common human diseases (Hatzel, 1983). They result from inadequate thyroid hormone production due to lack of sufficient iodine. Problems of IDD could be averted by a lowcost intervention; using universal salt iodization (USI). Since 1990, elimination of IDD has been an integral part of many national nutrition strategies (Zimmermann et al., 2008). In nearly all regions affected by iodine deficiency, the most effective way to control iodine deficiency is through salt iodization. Universal salt iodization (USI) is a term used to describe the iodization of all salt for human (food industry and household) and livestock consumption (WHO, UNICEF, ICCIDD 2007). Salt iodization is the recommended strategy for control of IDD because: Salt is one of few foodstuffs consumed by virtually everyone.

12 12 Salt intake is fairly consistent throughout the year. In many countries, salt production/importation is limited to a few sources. Iodization technology is simple and relatively inexpensive to implement. The addition of iodine to salt does not affect its color or taste. The quantity of iodine in salt can be simply monitored at the production, retail, and household levels. Urinary iodine excretion is a good marker of the very recent dietary intake of iodine and, therefore, is the index of choice for evaluating the degree of iodine deficiency and of its correction. Iodine concentrations in casual urine specimens of children or adults provide an adequate assessment of population iodine nutrition, provided a sufficient number of specimens are collected. (WHO, UNICEF, and ICCIDD. 2001). Nigeria having achieved sustained 98% of households access to adequately iodized salt since 1998 was certified as USI compliant in 2005 by the network for sustained elimination of iodine deficiency (SCN NEWS, 2007). This made Nigeria the first country in Africa to achieve this feat. Nigeria currently ranks 6th on the global iodized salt consumption out of the 200 countries assessed. The four goiter endemic states that prevented the country from recording 100% success in the universal salt iodization (USI) programme since its commencement in 1993 are Taraba, Benue, Nasarawa and Ebonyi States. The objective of the present study is to: To determine the availability of iodized salt in households in some areas of Abakaliki.

13 13 To access the adequacy of iodization of salt consumed by the population. To determine the urinary iodine status of children in the study population. The rationale for the study arises from recent report on backsliding on the usage of iodized salt/infiltration of un-iodized salt into the market. Therefore, there is need for re-assessment to know if the usage of iodized salts in our homes is maintained.

14 14 CHAPTER TWO LITERATURE REVIEW 2.1 Iodine Physiology Iodine is essential for normal growth, development, and functioning of the body. Since only minute amounts are required each day, it is known as a micronutrient. Iodine is required for synthesis of the thyroid hormones, thyroxine (T 4 ) and triiodothyronine (T 3 ), which are necessary for the regulation of body metabolism (Hetzel, 1989). In stable iodine intake situations, the amount of iodine excreted in the urine correlates well with the iodine intake and serves as an estimate of iodine intake. Less than 10% of human iodine losses are excreted in the faeces (Choufoer et al., 1963), sweat (Mao and Ko, 1990), and milk (Vermiglio et al., 1992). The stomach and the upper small intestine rapidly absorb iodine as either one of two chemical forms: iodide or iodate. Iodate is reduced to iodide, which is transported in the blood to the thyroid gland, where an active transport mechanism pumps it into the thyroid cell. About 60 μg of iodine needs to be trapped per day to maintain an adequate thyroxin level; the efficiency of the trapping mechanism is regulated with the help of Thyroid Stimulating Hormone (TSH) depending on the availability of iodine and the gland s activity. In the gland, iodide is oxidized to iodine, which is bound to tyrosine to form mono- and diiodotyrosine. These are coupled to form trioodothyronine (T 3 ) and thyroxin (T 4 ) in the thyroid epithelial cells. Thyroxin is then stored in colloid follicles bound to thyroglobulin. When needed, the TSH will stimulate the proteolysis of thyroglobulin in the thyroid cells to release thyroxin into the blood stream (Passmore and Eastwood, 1986; Hetzel, 1989).

15 Dietary Sources The native iodine content of most foods and beverages is low. In general, commonly consumed foods provide 3 to 80 µg per serving (Pennington et al., 1995 and Haldimann et al., 2005). Foods of marine origin have higher iodine content because marine plants and animals concentrate iodine from seawater. Iodine in organic form occurs in high amounts in certain seaweeds. Inhabitants of the coastal regions of Japan, whose diets contain large amounts of seaweed, have remarkably high iodine intakes amounting to 50 to 80 mg/d. In many countries, use of iodized salt in households for cooking and at the table provides additional iodine. Boiling, baking, and canning of foods containing iodated salt cause only small losses ( 10%) of iodine content (Chavasit et al., 2002). 2.3 Goitrogens Dietary substances that interfere with thyroid metabolism can aggravate the effect of iodine deficiency, and they are termed goitrogens (Gaitan, 1989). Cruciferous vegetables, including cabbage, kale, cauliflower, broccoli, turnips, and rapeseed, contain glucosinolates; their metabolites compete with iodine for thyroidal uptake. Similarly, cassava, lima beans, linseed, sorghum, and sweet potato contain cyanogenic glucosides; these may be metabolized to thiocyanates that compete with iodine for thyroidal uptake. For example, linamarin is a cyanogenic glycoside found in cassava, a staple food in many developing countries. If cassava is not adequately soaked or cooked to remove the linamarin, it is hydrolyzed in the gut to release cyanide, which is metabolized to thiocyanate (Ermans et al., 1972). Cigarette smoking is associated with higher serum levels of thiocyanate that may compete with iodine uptake. Smoking during the period of breastfeeding is associated with reduced iodine levels in breast milk (Laurberg et al., 2004).

16 16 Unclean drinking water may contain humic substances that block thyroidal iodination. Industrial pollutants may also be goitrogenic (Gaitan, 1989). It appears that most of these goitrogenic substances do not have a major clinical effect unless there is coexisting iodine deficiency. Goitrogens are usually active only if iodine supply is limited and/or goitrogen intake is of long duration. Many compounds have been tested in animals and have shown to possess anti-thyroid effects in vitro. These compounds belong to the following chemical groups: Sulfurated organics (like thiocyanate, isothiocyanate, goitrin and disulphides) Flavonoids (polyphenols) Polyhydroxyphenols and phenol derivatives Pyridines, phthalate esters and metabolites, Polychlorinated (PCB) and polybrominated (PBB) biphenyls Organochlorines (like DDT) Polycyclic aromatic hydrocarbons (PAH) Inorganic iodine (in excess) Lithium. 2.4 IODINE DEFICIENCY DISORDER (IDD). The term iodine deficiency disorders refers to all the ill-effects of iodine deficiency in a population that can be prevented by insuring that the population has an adequate intake of iodine (Hatzel, 1983, WHO, UNICEF, and ICCIDD. 2001). These effects include abortions, stillbirths, endemic cretinism, neonatal hypothyroidism, endemic mental retardation, goiter, impaired mental function, retarded physical development and others.

17 17 Iodine deficiency is now recognized as a global problem with large populations at risk who are living in an environment where the soil has been deprived of iodine. Brain damage and irreversible mental retardation are the most important disorders induced by iodine deficiency. It therefore appeared that iodine deficiency is the leading cause of preventable mental retardation (WHO, UNICEF, and ICCIDD. 1994). 2.5 Establishing Universal Salt Iodization (USI) in Nigeria USI was established by Law in 1993 to ensure effective iodization of edible salt in Nigeria. To provide legal backing for the effective regulation, Standard Organization of Nigeria (SON) produced the Nigerian industrial standard for food grade salt, NIS: 168/1992, regulating salt iodization using the potassium iodide (KI) as a fortificant. Based on a growing body of evidence from USI programs worldwide indicating major losses of potassium iodide, especially when sold in bulk in open air markets, SON published a revised standard for food grade salt, specifying potassium iodate (KIO 3 ) to improve retention (NIS 168:1994). The revised SON standard defines properly iodized salt as: > 50 ppm iodine at port of entry and salt factory level. > 30 ppm iodine at distributor and retail levels. > 15 ppm iodine at household level. As part of the standard, the salt is also required to be packed in smaller pack sizes of 250g, 500g and 1kg in high density polyethylene pouch. In addition to the registration number on salt bags indicating that the product has complied with the national standard, NAFDAC also introduced a logo that shows the salt is iodized.

18 Specific Iodine Deficiency Disorder a. Endemic goiter The term endemic goiter is a descriptive diagnosis and reserved for a disorder characterized by enlargement of the thyroid gland in a significantly large fraction of a population group and is generally considered to be due to insufficient iodine in the daily diet. Endemic goiter may be said to exist in a population when more than 5% of the preadolescent (6-12) school-age children have enlarged thyroid glands (WHO, UNICEF, and ICCIDD. 2001). A whole variety of naturally occurring agents have been identified that might be goitrogenic in man (Gaitan, 1980). Thiocyanate and precursors of thiocyanate, such as the cyanogenic glycosides form a group of widely distributed natural antithyroid substances. They have been found particularly in cassava tubers (Ermans et al., 1980). Cassava causes goiter when fed to rats (Ekpechi, 1967). Excessive intake of iodine may itself cause goiter. A localized endemia has been reported on the coast of Hokkaido in Northern Japan (Suzuki et al., 1965). In this district the diet contained a huge amount of seaweed and excretion of iodine in the urine exceeded 20 mg/day. Similar findings have been reported from coastal (Ma et al., 1982) and continental (Zhao et al., 2000) China. b. Cretinism Cretinism is a condition caused by a deficiency of thyroid hormone at birth and during infancy, as a result of abnormal development of the thyroid gland. About 1 in 4000 babies are affected. Cretinism causes very serious retardation of physical and mental development; if the condition is left untreated, growth is stunted and the physical stature attained is that of a dwarf. In addition,

19 19 the skin is thick, flabby, and waxy in color, the nose is flattened, the abdomen protrudes, and there is a general slowness of movement and speech. Cretinism (also called congenital hypothyroidism) may not be obvious at birth because thyroid hormone from mother's blood can benefit the baby before and several months after birth. Types of cretinism includes: endemic cretinism, neurological cretinism, myxedematous cretinism (Zimmermann, 2009). 2.7 Effects of iodine Deficiency through the Life Cycle a. Pregnancy and infancy. In areas of iodine sufficiency, healthy women maintain iodine stores of mg in the thyroid. During pregnancy, to help meet the approximately 50% increase in maternal iodine requirements women may draw on this significant iodine store (Glinoer, 1997, Elnagar et al., 1998, Zimmermann, 2009). However, in areas of chronic iodine deficiency, women enter pregnancy with already depleted iodine stores. With little thyroidal iodine to draw on to meet the increased maternal iodine requirement, pathological changes goiter and hypothyroidism may occur that can adversely affect maternal and fetal health. Iodized oil given to iodine-deficient pregnant women in Zaire at approximately 28 wk gestation decreased infant mortality (Thilly et a., 1994). In Algeria, rates of abortion, stillbirth, and prematurity were significantly lower among women given oral iodized oil 1 3 months before conception or during pregnancy than among untreated women (Chaouki and Benmiloud, 1994). Infant survival is improved in infants born to women whose iodine deficiency is corrected before or during pregnancy. DeLong et al. (1997) added potassium iodate to irrigation water over a 2- to 4-weeks period in three areas of severe iodine deficiency in China and found a large reduction in both neonatal and infant mortality in the following 2 3 years compared with areas that did not

20 20 receive iodine. The median urinary iodine increased in women of child bearing age from less than 10 to 55 µg/liter, whereas the infant mortality rate decreased in the three treated areas. Similar results were also observed for neonatal mortality; the odds of neonatal death were reduced by about 65% in the population who had iodine treatment. Infant survival may also be improved by iodine supplementation in the newborn period. A randomized, placebo-controlled trial of oral iodized oil (100 mg iodine) was conducted in an area of presumed iodine deficiency in Indonesia to evaluate the effect on mortality (Semba et al., 2008). The iodine or placebo was given in conjunction with oral poliovirus vaccine; infants (n = 617) were treated at approximately 6 weeks of age and were followed to 6 months of age. There was a significant 72% decrease in risk of infant death during the first 2 months of follow-up (Semba et al., 2008). In a large cross-sectional study in Indonesia, use of adequately iodized salt was associated with a significantly lower prevalence of child malnutrition and mortality in neonates, infants, and children younger than 5 years of age (Cobra et al., 1997). Taken together, these results suggest that iodine repletion in severely iodine-deficient pregnant women or infants may reduce the infant mortality rate by at least 50%. b. Childhood There have been many cross-sectional studies comparing cognition and/or motor function in children from chronically iodine-deficient and iodine-sufficient areas, including children from Asian and European backgrounds (Boyages et al.,1989, Choudhury and Gorman, 2003, Gao et al., 2004 and Amarra et al., 2007). These cross-sectional studies, with few exceptions, report reduced intellectual function and motor skills in children from iodine-deficient areas.

21 21 Several randomized, controlled trials in school-aged children have tried to measure the effect of iodized oil on cognition (Bautista et al., 1982, Shrestha 1994, Isa et al., 2000 and Huda et al., 2001). Three of the studies found no effect, whereas one found that cognition improved with treatment. c. Adulthood In adults, mild-to-moderate iodine deficiency appears to be associated with higher rates of more aggressive subtypes of thyroid cancer, increased risk for diffuse goiter, and increased risk of nontoxic and toxic nodular goiter and associated hyperthyroidism (Laurberg et al., 2001 and Zimmermann et al., 2008) Observational studies also suggest subtle but widespread adverse effects in adults secondary to hypothyroidism, including impaired mental function with decreased educability, apathy, and reduced work productivity (Hetzel, 1983). 2.8 Nutritional Status and Goiter Besides iodine deficiency and goitrogens, protein-calorie malnutrition also result in various alterations of thyroid morphology and function (Gaitan et al., 1986 and Medeiros Neto, 1989). Protein calorie malnutrition and endemic goiter frequently coexist and poor nutrition appears to increase the risk of goiter development in susceptible groups of the population (Gaitan, 1990). Studies demonstrate that malnourished individuals have the same thyroid gland abnormalities that have been shown in experimental animals to favour enlargement of the thyroid gland (Gaitan et al., 1983). A low protein diet in rats impairs the thyroidal transport of iodine, decreases iodine concentration in the thyroid, and is accompanied by an enlargement of the thyroid (Gaitan, 1990). Under these circumstances, the goitrogenic effect of antithyroid agents is enhanced. The

22 22 administration of protein reverses these alterations and decreases the action of such goitrogenic agents. 2.9 Thyroid Hormones. In the normal adult, the thyroid weighs about 25g and consists of two connected lobes, closely associated with the trachea. The thyroid hormones, thyroxine (T 4 ) and tri-iodothronine (T 3 ) are synthesized in the thyroid gland by iodination and coupling of two molecules of the amino acid, tyrosine, a process that is dependent on an adequate supply of iodine. Normally about a third of dietary iodine is taken up by the thyroid gland, a little by the mammary and salivary glands and the gastric mucosa. The rest is excreted by the kidney (Mayne, 2005) Metabolic effects of thyroid hormones a. Calorigenic effects. Thyroid hormone increases heat production and oxygen consumption. It was originally considered that this effect was mediated by uncoupling of oxidative phosphorylation in mitochondria, which would increase heat production and oxygen consumption, but recent research has not supported this hypothesis. Heat production may be a by-product of increased biosynthesis of mitochondrial proteins (Alberts et al., 1994). b. Effects of thyroid hormones on carbohydrate metabolism. i. Stimulates glycogenolysis in the liver. ii. Stimulates intestinal absorption of glucose. iii. Stimulates insulin breakdown.

23 23 c. Effect of thyroid hormones on lipid metabolism i. Increases lipolysis ii. Stimulates oxidation of fatty acids iii. Reduces plasma cholesterol by stimulation of oxidation of cholesterol to bile acid. d. Effects of thyroid hormones on protein metabolism. i. Stimulates synthesis of protein, mainly enzymes, involved in oxidative reactions and are necessary for a normal rate of protein synthesis. ii. Stimulate protein catabolism, especially in muscle when present in excess Treatment and Prevention a. Salt fortification with iodine Salt iodization remains the most cost-effective way of delivering iodine and of improving cognition in iodine-deficient populations (Engle et al., 2007). WHO/UNICEF/ICCIDD (2007) recommends that iodine is added at a level of mg iodine/kg salt, depending on local salt intake. Iodine can be added to salt in the form of potassium iodide (KI) or potassium iodate (KIO 3 ). Because KIO 3 has higher stability than KI in the presence of salt impurities, humidity, and porous packaging, it is the recommended form in tropical countries and those with low-grade salt (Diosady et al., 1997). In a multi-country study, high humidity combined with porous packing resulted in up to 90% losses of iodine in one year of storage through sublimation in high-density polyethylene bags, compared with 10 15% from low-density polyethylene bags (Diosady et al., 1998).

24 24 b. Other fortification vehicles. Bread can be an effective vehicle for iodine by including baker s salt enriched with iodine (Seal et al., 2007). Iodizing drinking water or irrigation water can also be effective (Cao et al., 1994). Iodine-containing milk is a major adventitious source in countries such as Switzerland and the United States (Haldimann et al., 2005) due to the use of iodophors in the dairy industry, rather than to the deliberate addition of iodine. In Finland, iodine-fortified animal fodder has increased the iodine content of foods derived from animal sources. In countries affected by IDD, whenever possible, iodine should be routinely added to complementary foods for weaning infants to provide approximately 90 µg of iodine per day (Dunn, 2003). c. Iodine supplementation In some regions, iodization of salt may not be practical for control of iodine deficiency, at least in the short term. This may occur in remote areas where communications are poor or where there are numerous small-scale salt producers. In these areas, iodized oil supplements can be used (WHO, UNICEF, ICCIDD, 2007). Iodine can also be given as KI or KIO 3 in drops or tablets. Single oral doses of KI monthly (30 mg) or biweekly (8 mg) can provide adequate iodine for school-age children (Todd et al., 1998). Lugol s iodine, containing approximately 6 mg iodine per drop, and similar preparations are often available as antiseptics in rural dispensaries in developing countries and offer another simple way to deliver iodine locally Increasing Iodine intakes in population and iodine excess. More than two thirds of the 5 billion people living in countries affected by iodine deficiency now have access to iodized salt (Zimmermann et al., 2008). Iodine excess is occurring more

25 25 frequently, particularly when salt iodine levels are too high or are poorly monitored. For example, in Brazil, Armenia, and Uganda, median urinary iodine is more than 300 µg/liter, whereas in Chile it is above 500 µg/liter (de Benoist et al., 2008, IDD Newsletter, 2009). High dietary iodine can also rarely come from natural sources, such as seaweed in coastal Japan (Nagataki, 2008), iodine-rich drinking water in China (Li et al., 1987), and iodine-rich meat and milk in Iceland from fish products used for animal feed (Sigurdsson and Franzson, 1998). The median urinary iodine in primary school-aged children in the United States is 229 µg/liter (Caldwell et al., 2008), resulting from iodine-containing agents used in dairying and food preparation and iodine fortified salt (Pearce et al., 2004) Side effects of iodine supplementation As discussed so far, iodine deficiency is associated with the development of thyroid function abnormalities. Similarly, iodine excess, including following overcorrection of a previous state of iodine deficiency, can also impair thyroid function. The effect of iodine on the thyroid gland is complex with a U shaped relation between iodine intake and risk of thyroid diseases as both low and high iodine intake are associated with an increased risk. It is stated that normal adults can tolerate up to about 1000 μg iodine/day without any side effects (WHO, 1994). The possible side effects of iodine excess are as follows: a. Iodide goiter and iodine-induced hypothyroidism. When the iodine intake is chronically high, as for example in coastal areas of Japan and China due to the chronic intake of seaweeds rich in iodine or in Eastern China because of the high iodine content of the drinking water from shallow wells, the prevalence of thyroid enlargement

26 26 and goiter is high as compared to normal populations and the prevalence of subclinical hypothyroidism is elevated (Ma et al., 1993). b. Iodine-induced hyperthyroidism (IIH) Iodine-induced hyperthyroidism (IIH) is the main complication of iodine prophylaxis. It has been reported in almost all iodine supplementation programs (Stanbury et al., 1998). IIH occurred in Tasmania in the late 1960 s following iodine supplementation simultaneously by tablets of iodide, iodized bread and the use of iodophors by the milk industry (Connolly et al., 1970). c. Iodine-induced thyroiditis In experimental conditions, excessive iodine intake can precipitate spontaneous thyroiditis in genetically predisposed strains of beagles, rats or chickens (Delange and Lecomte, 2000). The mechanism involved in iodine-induced thyroiditis in animal models could be that elevated dietary iodine triggers thyroid autoimmune reactivity by increasing the immunogenecity of thyroglobulin or by inducing damage of the thyroid and cell injury by free radicals. d. Thyroid cancer In animals, the chronic stimulation of the thyroid by TSH is known to produce thyroid neoplasms (Money and Rawson, 1950). However, the relationship between thyroid cancer and endemic goiter has often been debated without agreement being reached on many aspects, including on a possible causal relationship (Williams, 1985). In conclusion, it appears that the benefits of correcting iodine deficiency far outweigh its risks ((Delange and Lecomte, 2000). Iodine-induced hyperthyroidism and other adverse effects can be almost entirely avoided by adequate and sustained quality assurance and monitoring of iodine supplementation which should also confirm adequate iodine intake.

27 27 CHAPTER THREE MATERIALS AND METHODS 3.1 Experimental design. The study was carried out in Ohaozara and Abakaliki Local Government Areas (L.G.A s) of Ebonyi state. Five schools were selected from each L.G.A. 40 pupils from each school. A total of 400 pupils aged 6-12 years old were recruited for the study. The study involved qualitative and quantitative determination of iodine. 3.2 Qualitative determination of iodine. Qualitative determination of iodine was conducted by testing kitchen salt for iodine. The selected pupils were asked to collect 2 teaspoons of salt (about 10g) from their family kitchen. The salts were tested on the spot using rapid Iodized salt test kit and the color changes recorded. Rapid iodized salt test kits. The rapid iodized salt test kits were supplied by UNICEF. Principle: Iodide (I - ) as potassium iodide in iodized salt is converted to elemental iodine by potassium iodate in an acidic medium. The free iodine will react with starch to form a deep blue purple complex. In this reaction system the colour intensity of the iodine-starch complex is directly proportional to the liberated iodine and hence the iodide content of the salt.

28 28 Test apparatus a. metal or plastic pan. b. Iodized salt test kits (Test solution and Recheck solution) Procedure - a. The plastic pan was filled with salt. b. Two drops of test solution was to the surface of the salt. c. The colour on the salt was compared with the colour chart within one minute and the iodine content determined. If no colour appears on the salt after one minute, on a fresh sample add up to five drops of recheck solution and then add two drops of test solution on the same spot. Now compare the colour with the colour chart and determine the iodine content. 3.3 Quantitative determination of urinary iodine. Quantitative determination of urinary iodine was conducted by testing urine samples for iodine. Casual morning urine samples were collected from the selected pupils using plastic bottles screwed with caps. The samples were stored in a refrigerator until analysis. Urinary iodine was determined using ICCIDD/UNICEF/WHO standard method which involves the digestion of urine with ammonium persulphate ( ICCIDD,UNICEF,WHO. Dunn, 1993).

29 29 Principle Urine is digested with ammonium persulfate. Iodide is the catalyst in the reduction of ceric ammonium sulfate (yellow) to the cerous form (colourless), and is detected by the rate of colour disappearance (Sandell-Kolthoff reaction) Equipment Water bath Spectrophotometer Thermometer Test tubes (13 x 100 mm), assorted glassware and Storage bottles, pipettes, vortex, magnetic hotplate, magnetic stirrer, analytical balance. Reagents 1. Ammonium persulfate (H 8 N 2 O 8 S 2 ) 2. Arsenic trioxide (As 2 O 3 ) 3. Sodium chloride (NaCl) 4. Sulfuric acid (H 2 SO 4 ) 5. Sodium hydroxide (NaOH) 6. Ceric ammonium sulfate [Ce(NH 4 ) 4 (SO 4 ) 4 2H 2 O] 7. Deionized water (H 2 O) 8. Potassium iodate (KIO 3 )

30 30 Procedure The urine samples to be analysed were mixed to suspend sediments. With a micropipette, 250µl of each urine samples were added into a test tube. The same volume of 250µl of deionized water was also added into another test tube as blank. A volume of 250µl of each iodine standards (20, 40, 80, 120, 200, and 300 µg/l) were also pipetted into test tubes. To each of the set of test tubes (urine samples, water blank and iodine standards), 1.0ml of ammonium persulphate was added and mixed gently. All the tubes were heated for 60 minutes at 100 C followed by cooling at room temperature. To each of the test tubes, 2.5ml of arsenous acid solution was added and vortexed. The test tubes were allowed to stand for 15 minutes at room temperature. To each of the tubes, 300µl of ceric ammonium sulphate solution was added and quickly mixed at intervals of about seconds. The test tubes were allowed to stand at room temperature. Exactly 30 minutes after the ceric ammonium sulphate solution was added to the first test tube, the absorbance was read at 420 nm. The other successive tubes were read at the same interval of 30 minutes after ceric ammonium sulphate was added to the tube samples, blank and standards. 3.4 Calculation of result A standard curve was constructed on graph paper by plotting the iodine concentration of each standard on the abscissa against its optical density at 420 nm on the ordinate. From the curve, the urinary iodine concentration were determined for each sample assayed by finding its absorbance reading on the standard curve and subsequently locating its corresponding iodine concentration. The Median value, mode, mean, range, maximum, minimum and standard deviation were calculated using Microsoft 2007 excel.

31 31 CHAPTER FOUR RESULTS 4.1 Urinary iodine Concentration Table 4.1 shows the result of urinary iodine analysis in Abakaliki Local Government Area (L.G.A) of Ebonyi state. The result showed that 16 (8.04%) and 32 (16.08%) had moderate iodine deficiency and mild iodine deficiency respectively while 77 (38.69%) had adequate iodine nutrition. 40 (20.10%) and 33 (16.58%) were at risk of iodine induced hyperthyroidism and risk of adverse health consequences respectively. Table 4.1. Result of urinary iodine analysis: Abakaliki L.G.A. (n=199) UI Conc. µg/l IODINE INTAKE IODINE NUTRITION FREQUENCY PROPORTION % <20 Insufficient Severe iodine deficiency Insufficient Moderate iodine deficiency Insufficient Mild iodine deficiency Adequate Optimal More than adequate. Risk of iodine induced hyperthyroidism >300 Excessive Risk of adverse health consequences

32 32 Table 4.2 shows the result of urinary iodine analysis in Ohaozara Local Government Area (L.G.A) of Ebonyi state. The result showed that 1 (0.50%) had severe iodine deficiency, 38 (19.09%) had moderate iodine deficiency, 28 (14.07%) had mild iodine deficiency while 70 (35.17%) had adequate iodine nutrition. 45 (22.61%) and 17 (8.54%) were at risk of iodine induced hyperthyroidism and risk of adverse health consequences respectively. Table Result of urinary iodine analysis: Ohaozara L.G.A. (n=199) UI Conc. µg/l IODINE INTAKE IODINE NUTRITION FREQUENCY PROPORTION % <20 Insufficient Severe iodine Deficiency Insufficient Moderate iodine deficiency Insufficient Mild iodine deficiency Adequate Optimal More than adequate. Risk of iodine induced hyperthyroidism >300 Excessive Risk of adverse health consequences

33 33 Table 4.3 shows the result of urinary iodine analysis of the whole study population (Abakaliki and Ohaozara local government areas). It showed that 1 (0.25%) had severe iodine deficiency, 54 (13.81%) had moderate iodine deficiency, 60 (15.07%) had mild iodine deficiency while 148 (37.18%) had adequate iodine nutrition. 85 (21.35%) and 50 (12.56%) were at risk of iodine induced hyperthyroidism and risk of adverse health consequences respectively. Table 4.3. Result of urinary iodine analysis: Total study population (n=398) UI Conc. IODINE IODINE FREQUENCY PROPORTION µg/l INTAKE NUTRITION % <20 Insufficient Severe iodine deficiency Insufficient Moderate iodine deficiency Insufficient Mild iodine deficiency Adequate Optimal More than adequate. Risk of iodine induced hyperthyroidism >300 Excessive Risk of adverse health consequences

34 34 Table 4.4 shows that the Median Urinary Iodine (MUI) value for Abakaliki and Ohaozara is 160 µg/l and 140 µg/l respectively while that of the total study population is 145 µg/l. Table 4.4. Summary of urinary iodine concentration (µg/l) LGA MIN-MAX MEAN ±SD MEDIAN ABAKALIKI ± OHAOZARA ± TOTAL POPULATION ± Household Salt Iodine Testing Table 4.5 shows the result of household salt iodization and testing in Abakaliki Local Government Area. It showed that out of 200 salt samples collected form 200 families, 4 (2%) had no iodine, 75 (37.5%) had inadequate iodine content (<15ppm) and 121 (60.5%) had adequate iodine content (> 15ppm). Table 4.5. Result of household salt iodization & testing: Abakaliki L.G.A (n = 200) S/N IODINE CONTENT FREQUENCY % 1. 0 ppm 4 2 (no) 2. < 15 ppm (inadequate) 3. >15 ppm (adequate)

35 35 Table 4.6 shows the result of household salt iodization and testing in Ohaozara Local Government Area. It showed that out of 200 salt samples collected form 200 families, 36 (18%) had no iodine, 31 (15.5%) had inadequate iodine content (<15ppm) and 133 (66.5%) had adequate iodine content (> 15ppm). Table Result of household salt iodization & testing: Ohaozara L.G.A (n = 200) S/N IODINE CONTENT FREQUENCY % 1. 0 ppm (no) 2. < 15 ppm (inadequate) 3. >15 ppm (adequate)

36 36 Table 4.7 shows the result of household salt iodization and testing of the general study population (Abakaliki and Ohaozara local government areas). It showed that out of 400 salt samples collected form 400 families, 40 (10%) had no iodine, 106 (26.5%) had inadequate iodine content (<15ppm) and 254 (63.5%) had adequate iodine content (> 15ppm). Table 4.7. Result of household salt iodization & and testing: Total study population ( n = 400) S/N IODINE CONTENT FREQUENCY % 1. 0 ppm (no) 2. < 15 ppm (inadequate) 3. >15 ppm (adequate) Results of the Household salt iodization testing (Tables 4.5 and 4.6) showed that 60.5 and 66.5% of household salt samples were adequately iodized (>15ppm) in Abakaliki and Ohaozara LGAs respectively. 2.0% of household salt from Abakaliki LGA and 18% from Ohaozara LGA were non- iodized.

37 37 Fig. 4.1: % Household access to Iodized salt % no iodine iodine below 15 ppm iodine above 15 ppm 0 MICS 2007 EBONYI STATE 2010

38 38 Fig. 4.2.Comparison of Universal Salt Iodization (USI) assessments in Nigeria % BS 1999 MICS 2002 N.A 2003 NDHS 2003 N.A2005 N.A 2007 MICS 2008 NDHS 2010 EBONYI STATE BS: Baseline Survey, MICS: Multiple Indicator Cluster Survey, NDHS: National Demographic Health Survey, NA: National Assessment.

39 39 CHAPTER FIVE DISCUSSION 5.1 Assessment of urinary iodine status. Assessing urinary iodine status provides information on whether there is adequate iodine intake in the population surveyed. Monitoring the urinary iodine status of a population is helpful in knowing if salt iodization program (or other interventions) is improving iodine intake and if iodine deficiency has been eliminated in the population. Urinary Iodine status is the most immediate measure of whether the thyroid gland has adequate iodine to function normally and protect the individual from the manifestations of iodine deficiency. Urinary iodine concentration is currently the most practical biochemical marker for iodine nutrition. This approach assesses iodine nutrition only at the time of measurement. Assessment of body iodine content through the measurement of excreted iodine based on classification of iodine nutrition of the studied population, using the joint criteria of WHO, UNICEF and ICCIDD (2001) had shown the urinary iodine concentration ranging between µg/l to be sufficient. Higher incidence of insufficient iodine nutrition (<20-99 µg/l ) occurred in Ohaozara (67 pupils representing 33.66%) (Table 4.2) than in Abakaliliki (48 pupils representing 24.12%) (Table 4.1), while higher incidence of more than adequate iodine intake (200- >300 µg/l) occurred in Abakaliki (73 pupils representing 36.68%) than in Ohaozara (62 pupils representing 31.15%). Insufficient iodine nutrition could result to iodine deficiency disorder (IDD) and more than adequate iodine nutrition could result to risk of iodine induced hyperthyroidism with adverse health consequences.

40 40 In the total study population, 115 pupils (29.13%) had insufficient iodine intake (<20-99 µg/l), 148 pupils (37.18%) had adequate iodine intake ( µg/l) and 135 pupils had more than adequate iodine intake (200- >300 µg/l) (Table 4.3). This is in accordance with the WHO/ICCIDD/ UNICEF (1994) criteria for monitoring for monitoring progress towards eliminating IDD as a public health problem. According to this criteria, the proportion with urinary iodine below 100 µg/l should be <50% and the proportion with urinary iodine below 50 µg/l should be <20%. The median urinary iodine concentration for the total study population is 145 µg/l which is within the sufficient / optimal range. Result of surveys conducted in Nigeria like the 1999 sentinel site survey, 2001 national food consumption and nutrition survey and 2005 goiter prevalence survey had median urinary iodine excretion within the sufficient / optimal range as µg/l, 150 µg/l and 131 µg/l respectively (SCN NEWS, 2007). Iodine deficiency is still a serious public health problem in many countries in the world and it results from inadequate iodine intake. Brazil is a country historically affected by iodine deficiency and severe endemic goiter and cretinism were reported (IDD Newsletter, 2009). Moderate to severe endemic goiter due to iodine deficiency has been historically found in the western part of Argentina (IDD Newsletter, 2009). Urinary iodine excess occurs particularly when salt iodization is excessive and poorly monitored. Tolerance to high doses of iodine is quite variable and many individuals ingest amounts of several milligrams or more per day without apparent problems. The median urinary iodine in primary school-aged children in the United States is 229 µg/l(caldwell et al., 2008), as a result

41 41 of iodine-containing agents used in dairying and food preparation, together with iodine from fortified salt (Pearce et al., 2004). In Armenia, and Uganda, median urinary iodine is more than 300 µg/l as a result of high level of iodine in salt (IDD Newsletter, 2005), whereas in Chile it is above 500 µg/l as a result of law mandating the iodization of all salt for human consumption at 100 ppm (IDD Newsletter, 2009). In Brazil, autoimmune thyroiditis/iodine-induced hyperthyroidism was reported as a result excessive iodine intake (IDD Newsletter, 2009). Children in Urban area (Abakaliki) with median urinary iodine concentration of 160 µg/l had higher iodine intake than children in the rural area (Ohaozara) with median urinary iodine concentration of 140 µg/l. similar situation occurred in Serbia (IDD Newsletter, 2010). The result of this investigation demonstrated that despite normal median urinary iodine, cases of insufficient iodine intake and excessive iodine intake still exist. The most likely explanation is the uneven iodization of the salt. The requirement of >90% household consumption of iodized salt with 15 ppm of iodine has not been met Monitoring salt at the household level Monitoring iodine in salt at the household level provides information on what percentage of households uses salt iodized at any iodine concentration and what percentage uses salt that is within an acceptable range of iodine concentration. This information indicates what is actually used in households on a national basis and provides important information about the successful delivery of iodized salt to the consumer as well as about use of non-iodized salt obtained from unconventional marketing sources.

42 42 Tables 4.5 and 4.6 shows that 98% and 82% of pupils/households in Abakaliki and Ohaozara respectively consume iodized salt as of the time of the survey. In 66.5 % of the households in Ohaozara, salt was found to be adequately iodized and contained 15 parts per million (ppm) or more of iodine; while 15.5 % of households had iodized Salt with less than 15 ppm of iodine and 18.0% of the pupils/households consume un-iodized salt (Table 4.6). In 60.5% of the households/pupils in Abakaliki, salt was found to be adequately iodized and contains about 15 parts per million (ppm) or more of iodine; while 37.5% of the households/pupils had iodized salt with less than 15ppm of iodine and 2.0% of the pupils/households consume un-iodized salt (Table 4.5). In the total study population (Table 4.7), 90.0% of the total household salt samples collected during the survey proved iodized, only 63.5% were adequately iodized (>15ppm). This proportion is below the threshold of above 90% recommended by WHO/UNICEF/ICCIDD and the national average value of 98% attained in Comparison of the result of salt iodization of this study with the result of Multiple Indicator Cluster Survey (NBS, 2007) (Fig 4.2) showed a decline in household consumption of adequately iodized salt and increase in household consumption of inadequately iodized and non-iodized salt. Fig 4.3 is a comparison of Universal Salt Iodization (USI) in Nigeria since 1993 which reviled that there was a decline in USI level from Similar situation occurred in Ethiopia (IDD Newsletter, 2010) where iodized salt consumption dropped to as low as 5% as a result of consumption of locally produced un-iodized salt. In Indonesia, CBS (2005) indicated 73% of

43 43 households as consuming adequately iodized salt. Later surveys indicated a fall in this number to 62.8%. This decline was attributed to low quality iodization. Also decline in USI was observed in Argentina in the 1980s and 1990s. The main reason for this relapse were poor comprehension of the problem and its magnitude, inadequate governmental support, the absence of educational efforts, no law enforcement and absent or inadequate monitoring. Non-iodized salt samples detected in this survey could be attributed to iodine losses at the retail level, particularly when exposed to moisture and direct sunlight after decanting from 20 kg bags and displayed in open bowls (mudus) in the open market. It could also be locally produced salt since there are many salt lakes in the state. Some of the salts may have not been adequately iodized at the site of production. Distributing salt in smaller, airtight and moisture proof consumer packs of 500 grams will significantly improve retention of iodine. Some households still consume non-iodized salt because it is more directly available, cheaper and because of the lack of awareness on adverse health consequences associated with the consumption of un-iodized salt.