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Brief Reports Indian Pediatrics 2003; 40:406-409 |
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Assessment of Iodine Deficiency Disorders in Urban Areas of Udaipur District, Rajasthan |
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Iodine deficiency not only causes endemic goiter and cretinism but also a wide spectrum of disabilities like deaf mutism, mental and physical retardation and various degrees of neuromotor dysfunction(1). In India more than 150 million people are at the risk of Iodine Deficiency Disorders (IDD); 54 million have goitre, 2.2 million suffer from cretinism and an estimated 6.6 million are affected by milder neurological defects(2). In 1993, a goiter prevalence of 10.2 per cent was reported from Udaipur district(3). According to WHO the area is classified as endemic if more than 5% of school age children (6-12) are found to be suffering from goiter(4). Thus, on the basis of goiter prevalence, the Udaipur district has been identified as one of the endemic areas for the deficiency of iodine. Considering the fact that no recent data is available for Udaipur district, the present study was conducted with the objectives to assess the current prevalence of iodine deficiency disorders in urban areas of Udaipur district and to estimate the iodine content of salt consumed by the population. Subjects and Methods The study was conducted in the urban areas of Udaipur district, Rajasthan. A stratified multistage sampling design was used for selecting children in the age group of 6-12 years from five directional zones namely, East, West, North, South and Center. From each of these zones all the schools were enlisted and two coeducational senior secondary schools were selected. Subse-quently, children in the age group of 6-12 years were identified from school records for inclusion in the study. Children in this age group were selected because of their combined high vulnerability to the disease, representativess of their age group in community and easy accessibility(4). The school teachers and children were briefed about the deficiency of iodine and activities to be undertaken for the study. The sample size of the children to be surveyed was calculated with a presumption that the prevalence of goiter at the time of survey was 15%. Utilising the confidence level of 95% and a relative precision of 10% a sample size of 2190 children was calculated. The clinical examination of goiter was done using the traditional recommended method of thyroid palpation after obtaining training from an expert endocrinologist at Maharana Bhopal Singh Government Hospital, Udaipur. Grading of goiter was done according to the criteria recommended by WHO/UNICEF/ICCIDD(4). The sum of percentages of goiter grade I and grade II provided the Total Goiter Rate (TGR) in the study population. The percentage of goiter grade II provided the Visible Goiter Grade (VGR) for the study population. On the spot urine samples were collected from nearly 10% of the subjects. The casual urine samples of each subject was collected in wide mouthed screw capped plastic bottle and a drop of toluene was added to inhibit bacterial growth and to minimise bad odour. Collected urine samples were refrigerated till analysis. Iodine in urine was determined by wet digestion method(5) at Human Nutrition Unit, All India Institute of Medical Sciences Sciences, New Delhi. The results were expressed as mcg of iodine/dL of urine. For estimation of iodine content in the salt, from each zone nearly 50 salt samples were collected from the households of the children included in the study. The subjects were asked to bring about 20 g of salt which was being used in their respective homes in the auto seal polythene pouches. The iodine content of salt was estimated using the standard iodometric titration method(6) at Human Nutrition Unit, All India Institute of Medical Sciences, New Delhi. Results A total of 2329 children in the age group of 6-12 years were included in the study (1448 males and 881 females). The total goiter prevalence rate was found to be 8.4% and visible goiter rate was found to be 0.3%. The prevalence of goiter was found to be higher among females as compared to males but the difference was not statistically significant. However, prevalence of goiter increased with increase in age. Urinary iodine levels were estimated in about 300 casual urine samples. It was found that 0.3, 0.7 and 7.3 percent of the children had deficient Urinary Iodine Excretion (UIE) at the level of <2, 2-4.9 and 5-9.9 mcg/dL, respectively. The median urinary iodine levels of the study population was 20 mcg/dL. Analysis of 281 salt samples revealed that uniodised salt was not consumed by any of the beneficiaries. Only 15% of the salt samples had iodine content less than the stipulated level of 15 ppm of iodine and rest 85% were consuming salt with iodine content 15 ppm or more. Discussion The area is classified as endemic for iodine deficiency if more than 5% of school age children (6-12 years) are found to be suffering from goiter(4). In the present study, a total goitre prevalence rate of 8.4% was found. An earlier prevalence of 10.2% was reported by WHO(3) in the Udaipur district. The decrease in the prevalence of goitre could possibly be attributed to the availability of iodised salt to the population. Similar decline in the prevalence of iodine deficiency from 22.9 in 1990(3) to 20.5 in 1997(7) has been reported in the district of Bikaner(7). In 1999, following the intensive salt iodisation programme a decrease in the prevalence of Total Goiter Rate has also been reported by other authors(8). WHO(4) recommends that iodine deficiency is not a public health problem in a population when median urinary iodine excretion is more than 10 mc/dL. In the present study population median urinary iodine excretion of the children was 20 mcg/dL indicating normal iodine nutriture. Positive impact observed in the present study is in conformity with the result of the pilot surveys(9) conducted during 1996-1999 to assess urinary iodine levels in the population in 28 districts of 8 states (including Rajasthan) and 1 union territory of the country. In all the states the median urinary iodine levels were 10 mcg/dL or more except for district Lakhimpur Kheri, Uttar Pradesh. Estimation of iodine levels in the salt samples revealed that all salt samples were iodised but only 85% of salt samples were adequately iodised i.e., salt with iodine content of 15 ppm or more. It was interesting to note that the none of the salt samples had nil iodine content indicating effective implementation of National Iodine Deficiency Disorders Control Programme in the urban areas of Udaipur district. The result of the decline in the goiter prevalence as well as in the biochemical deficiency i.e., urinary iodine excretion are consistent with other studies(7,8). However, one study(10) revealed that except for the state of Goa (49.1) and Rajasthan (68.1), in all other states studied namely Bihar, Madhya Pradesh, Haryana, Punjab, Himachal Pradesh, Delhi, Andaman and Nicobar and Pondicherry, more than 90 per cent of salt samples were iodised. Further, in all the other states the number of salt samples which had nil iodine content varied from 0 to 6% with the exception of Rajasthan (31.9) and Goa (48.9). In conclusion, the urban area of Udaipur district appears to be in transition from iodine deficient to iodine sufficient which is evident from the decrease in prevalence of clincial deficiency and absence of biochemical deficiency. Consumption of adequately iodised salt by more than 85 per cent study population shows effective implementation of salt iodisation programme. Acknowledgement The financial aid provided by Indian Council of Medical Research, New Delhi to conduct the study is duly acknowledged. We are also thankful to the School Principals, teachers and students for their kind cooperation in data collection. Contributors: RP conducted the study and drafted the manuscript. MC guided and supervised the study. Funding: The study was funded by Indian Council of Medical Research, New Delhi. Competing interests: None stated.
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