The prevention and treatment of IDD should focus on science
2022-05-16
May 15 is the 29th "national iodine deficiency disease prevention and treatment day". This year's theme is "smart life, healthy road, the first step of scientific iodine supplementation". What is the cognitive process of IDD? How is the prevention and treatment of IDD scientifically carried out in China? For individuals, how to know their iodine nutritional status and then supplement iodine scientifically? The reporter interviewed a number of industry experts. Scientific cognition: never forget the pain after the scar is healed "IDD is a general term for a group of diseases, including endemic goiter, endemic cretinism, and abortion, premature delivery, stillbirth, fetal malformation caused by iodine deficiency." Liu Peng, director of the iodine deficiency disease prevention and Control Institute of the endemic disease control center of the Chinese Center for Disease Control and prevention, said that China's ancient medical book Shennong materia medica had records of goiter and mentioned that seaweed was a good medicine for the disease. "But this is only a description of the disease and symptomatic treatment. The scientific cognition of human etiology began in the 19th century." At that time, human beings found iodine and confirmed that thyroxine was an active ingredient in the thyroid, and the iodine content in the thyroid of patients with goiter was significantly low. Many discoveries in medical physiology make people understand that iodine is an essential trace element for human body and an important raw material for the synthesis of thyroid hormone. These provide a scientific basis for explaining the relationship between iodine deficiency and goiter. This year, China's "iodine deficiency disease prevention and control day" focuses on the role of iodine on the brain development of fetuses and infants, that is, iodine deficiency can cause endemic cretinism. Liu Peng said that scientific research has found that thyroid hormone can promote the intellectual development of the brain, especially in the fetal period and 0-3-year-old infants, which is the key period of brain development. At this time, if there is a lack of iodine supply, the normal development of the brain will be affected. Therefore, iodine is also known as "wisdom element". Liu Peng said that the fact of iodine deficiency in the natural environment cannot be changed, and the prevention and treatment of IDD can only be through human intervention. The World Health Organization clearly pointed out in 1994 that "universal salt iodization is the main public health means to eliminate IDD". In 2000, China basically achieved the goal of eliminating iodine deficiency diseases. Practices at home and abroad have fully proved that salt iodization is the most economical, effective and convenient measure to prevent and treat IDD. In 2017, the national health and Family Planning Commission organized a national survey on the iodine content of drinking water, and investigated the iodine content of drinking water in villages and towns. The survey results show that the iodine content in the external environment in most areas of China is low. We should continue to adhere to the strategy of universal salt iodization, and implement various prevention and control measures according to the principles of adjusting measures to local conditions, classified guidance and scientific iodine supplementation. "In short, from a scientific point of view, iodine supplementation is a matter that needs to be adhered to for a long time. We can't relax just because our country has eliminated iodine deficiency disease. We should never forget the pain when we get rid of the scar." Liu Peng said. Scientific prevention and control: continuous monitoring and dynamic adjustment In 1991, Shen Hongmei, who had just joined the work, witnessed the Chinese government's signing of the United Nations World Declaration on the survival, protection and development of children, and solemnly promised the international community that China would achieve the goal of eliminating IDD by 2000. "In order to achieve this goal as scheduled, China has taken a series of actions." Shen Hongmei, now deputy director of the center for endemic disease control of the China CDC, said. "Over the past 20 years, China's iodine deficiency disease prevention and control strategy has been continuously adjusted." Shen Hongmei said that the first time was in 1996. The upper limit of iodine content in iodized salt was set to 60 mg / kg. The second adjustment was in 1998. At that time, the Ministry of Health issued a document to stop the expansion and abuse of iodine fortifiers, and strengthen the concept and measures of scientific iodine supplementation. The third time in 2000, the iodine content standard of edible salt was lowered to 35 mg / kg. The fourth adjustment was in 2011. According to the principles of adjusting measures to local conditions, classified guidance and scientific iodine supplement, the average level of iodine content in edible salt was adjusted to 20 ~ 30 mg / kg based on iodine element according to the standard of iodine content in edible salt, and the provincial health administrative departments were required to adjust measures to local conditions according to the actual situation of iodine nutrition level of local people. The allowable fluctuation range of iodine content in iodized salt was 30% up and down of the determined iodine level. "Behind the dynamically adjusted prevention and control strategy is the scientific basis provided by continuous monitoring." Shen Hongmei said that the monitoring of IDD in China began in 1989, and the current monitoring indicators have covered IDD condition indicators, population iodine nutrition indicators and the implementation of prevention and control measures. "Monitoring is also developing." Shen Hongmei said that in July 1989, the Department of endemic disease prevention and control of the Ministry of health formulated the "standards and monitoring plan for the prevention and control of iodine deficiency diseases"; After the signing of the World Declaration on the survival, protection and development of children in 1991, in view of the fact that the original key monitoring can no longer meet the needs of understanding the condition of IDD in the whole country, China decided to change the key monitoring in some areas to nationwide random sampling monitoring, including IDD condition monitoring and iodized salt monitoring. After the discovery of cretinism patients in young age in southern Xinjiang in 2006, in order to strengthen the organic combination of IDD monitoring and prevention and intervention measures, the Ministry of health revised the national IDD monitoring plan and the national iodized salt monitoring plan in 2007, involving three parts: iodized salt monitoring, IDD high-risk area monitoring, investigation and evaluation, and strengthened the monitoring of key areas and key populations. "As there are still excessive iodine hazards caused by excessive iodine content in drinking water in some areas of China, monitoring in areas with high water iodine was added in 2012." "The most recent revision was in 2016." Shen Hongmei said that this time, the monitoring scope was expanded to all counties in the country, realizing the full coverage of IDD monitoring at the county level. At the same time, the monitoring contents were adjusted to once a year, which enhanced the timeliness of monitoring. Scientific iodine supplement: know your iodine status Because most of the external environment (water, soil, etc.) is iodine deficient, the iodine stored in the human body can last up to 3 months, so it is necessary to supplement iodine continuously through diet. "The diet mainly includes food, drinking water and iodized salt." Yang Xiaoguang, a researcher at the Institute of nutrition and health of the Chinese Center for Disease Control and prevention, said that residents in most areas get about 10 micrograms of iodine from drinking water and 25-50 micrograms of iodine from food every day, which is far from reaching the daily requirement of 120 micrograms and must be supplemented by iodized salt. "Although the iodine content in marine food is high, the intake of iodine rich food is low, which can not independently meet the human body's demand for iodine. Iodized salt should also be eaten. In addition, in areas with high water iodine or areas with high iodine goiter, salt without iodine should be eaten to avoid high iodine goiter." For individuals, how to know their iodine status and then supplement iodine scientifically? Yang Xiaoguang said that there are two kinds of indicators to evaluate the iodine nutritional status. One is the index used to evaluate the iodine nutrition of the group, including the content of urinary iodine, the rate of goiter and the positive rate of neonatal thyroid stimulating hormone screening. "Use these indicators to monitor the iodine nutrition status of the national population and adjust the prevention and control strategies in time." The other is thyroid volume and serum iodine. Yang Xiaoguang admitted that although these two indicators can be used to evaluate individual iodine nutritional status, their practicability is limited. For example, thyroid volume can be obtained through detection, but iodine deficiency or iodine excess can lead to goiter. In addition, the detection of serum iodine requires sophisticated equipment and professional analysts, which is difficult to popularize. "In the future, we need scientific and technological innovation, research and development of detection means, similar to blood glucose meter, just take a test paper." "Under the existing conditions, a more practical method is to scientifically estimate their daily iodine intake and compare it with the relevant indicators in the reference intake of dietary nutrients for Chinese residents formulated by the Chinese Nutrition Society, so as to scientifically determine their iodine nutritional status." Yang Xiaoguang said that the "reference intake of dietary nutrients for Chinese residents" has clearly defined the daily safe intake range of iodine for children aged 4-6, 7-10, 11-13, adolescents aged 14-17, ordinary adults, pregnant women and lactating women, and the corresponding standard iodized salt can be selected accordingly. "For example, if the iodine content of table salt is 25 mg / kg, the daily intake of 5 grams of table salt is calculated based on the cooking loss rate of 20%. The intake of 100 micrograms of iodine from iodized salt, plus the iodine obtained from water and food, can meet the needs of most people. Pregnant women and lactating women also need to intake seafood rich in iodine once or twice a week; especially pregnant women, thyroid function should be monitored to prevent the lack of iodine intake from affecting the health of the fetus Normal development. " Science Education: reject rumors and "carry the pot" In recent years, the prevalence of thyroid diseases has increased year by year. Many people believe that it is related to the consumption of iodized salt, which is caused by excessive iodine. "It's wrong to let iodized salt carry this pot." Shan Zhongyan, chief physician of the Department of Endocrinology and metabolic diseases of the First Affiliated Hospital of China Medical University, said that the increase in the incidence rate of thyroid nodules and thyroid cancer was not directly related to iodine excess. Shan Zhongyan said that there are standards for the evaluation of iodine nutritional status of ordinary people. When the median urinary iodine of adults exceeds 300 μ g / L, it belongs to iodine excess, and less than 100 μ g / L is iodine deficiency. Hypothyroidism caused by iodine deficiency often occurs in iodine deficiency areas. Eating iodized salt is the most effective method. The degree of hypothyroidism caused by iodine excess is relatively light, and subclinical hypothyroidism is common. At this time, it is necessary to find out the causes of iodine excess, such as high water iodine and eating too many iodine rich foods, so as to limit the intake of iodine. "At present, scientific research has concluded that clinical hyperthyroidism and subclinical hypothyroidism are related to iodine nutrition excess." But there is no evidence that iodine excess is associated with an increased incidence rate of thyroid nodules, Shan said. "Patients with thyroid cancer can eat a normal iodine diet. If they are treated with radioactive iodine nail cleaning or focal cleaning after surgery, they need a low iodine diet before treatment." Shan Zhongyan said that there are misunderstandings in preventing thyroid cancer by not eating iodized salt. Iodine deficiency will reduce the proportion of papillary thyroid cancer with low malignancy and good prognosis, and increase the proportion of pathological types with high malignancy. "It is recommended that patients with thyroid cancer take enough iodine under the advice of doctors". Another rumor about eating iodized salt is that it can prevent radiation. In this regard, Shan Zhongyan said that taking a large amount of iodine, such as iodine tablets, can prevent the intake of radioactive iodine. The conventional dose of iodine tablets is 100 mg / tablet. In most areas of China, the iodine content of iodized salt is generally 20 ~ 30 mg per kilogram of table salt. "To achieve the same iodine content of iodine tablets, you need to eat 3 ~ 5 kg of table salt at a time. Therefore, it is impossible to prevent the radiation of radioactive iodine by eating iodized salt". Short comment Take the road of sustainability □ Zhang Lei In 1991, the Chinese government signed the United Nations World Declaration on the survival, protection and development of children, and solemnly promised the international community to achieve the goal of eliminating IDD by 2000. By taking effective measures such as popularizing salt iodization, China basically achieved this goal in 2000, which has been 22 years now. After 22 years of unremitting efforts, China has maintained the state of continuous elimination of iodine deficiency diseases. Iodine deficiency diseases such as endemic goiter and endemic cretinism have been relatively rare. At the same time, it should be recognized that iodine deficiency in the natural environment is an objective fact that cannot be changed. Supplementing iodine required by the human body through diet is a long-term measure. If we cannot adhere to and improve the sustainable elimination of IDD
Edit：Yuanqi Tang Responsible editor：Xiao Yu
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