| ObjectiveTo obtain people’s iodine nutritional status of different regions with varied iodine concentrations of iodine through epidemiological investigation and laboratory examination. We also acquire the morbidity of thyroid nodule, electrocardiographic abnormality and carotid artery plaque and the level of blood lipid and hemorheology and to explore the effect of high iodine on the cardiovascular system and the possible mechanism.Methods1. The choice of populationWe chose three investigation group according to the criterion of iodine in water including low iodine group (LI,<10μg/L), normal iodine group (NI,50-150μg/L), high iodine group (HI,150-300μg/L). We adopt the method of stratified sampling to selected 3-5 villages in every group and choose the subject accordance with the inclusion criteria. The inclusion criteria include:(1) at the age of 20-65 years old; (2) the people are local farmers and have no relocation; (3) people use the same drinking water and eat locally produced food and vegetables, and don’t have other iodine supplement way; (4) agree with the investigation and able to complete the questionnaire; (5) people have no endemic fluorosis or other endemic diseases.2. The content of the investigationThis survey includes two parts, namely the nutrition survey and epidemiological survey and the nutrition survey includes 3 days 24 hour dietary survey and food frequency questionnaire.3 days 24 hour dietary questionnaire is used to record the investigation object of three consecutive days of food intake and calculate the intake of various nutrients. Food frequency questionnaire designed by ourselves incorporate into the regular consumption food of local and high iodine content food. We calculated the food iodine intake by food frequency questionnaire and detecting the iodine content of local food. And we calculated the water iodine intake according to the water consumption and water iodine content. People’s iodine nutritional status is the sum of food iodine and water iodine intake. The epidemiology survey includes general survey and physical examination. General survey includes gender, age, nationality, occupation, marital status and other general information. Physical examination includes height, weight, waist circumference, hip circumference, blood pressure, thyroid ultrasound, electrocardiogram, carotid ultrasound examination. At the same time includes the laboratory tests of urinary iodine, blood lipid and hemorrheology.3day dietary questionnaires were converted into Excel tables using nutrition calculator V2.65 software. The other questionnaire and physical examination data were imported into Epidata3.1 software. All data were analyzed using SPSS 20.0 software.Results1. Basic situationThis investigation got 1378 effective questionnaires, including 458 in low iodine group,450 in normal iodine group and 470 in high iodine group. And it contained Male 503 and female 875. Age distribution between 20 to 65 years old and the median age was 50. There was no difference of gender, age, height, weight, BMI and other basic situation among groups.2. The iodine nutritional status of different groupsThe food iodine intake in LI group was higher than NI group and HI group. The tendency of water iodine intake and iodine nutrition status in sequence from high to low was:HI group, NI group and LI group. In all the food, aquatic product kind at the top contribution to iodine nutrition, accounted for 51.44%, then is vegetables, staple food, beans, meat, eggs, milk, fruit and nuts. It showed significant correlation between urinary iodine and iodine nutrition (P< 0.05), and the correlation coefficient was 0.267.3. The indexes of physical examination of different groups3.1 The examination of thyroid ultrasonic of different groupThe thyroid volume in NI group was higher than LI group, while there was no difference of the goiter rate among groups. Compared with LI group, the incidence of thyroid nodule and single nodular in NI group and HI group were higher (P< 0.05). The nodule boundary unclear ratio of HI group was higher than HI group and NI group (P< 0.05). The node size, nature, echo, shape, calcification rate showed no difference among the group.3.2 The blood lipid and hemorrheology of different groupsThe level of serum total cholesterol in HI group was higher than LI group and NI group (P< 0.05). The value of low density lipoprotein cholesterol of LI group was the highest in the three groups, next was NI group, and it was the lowest in HI group. The radio of high-density lipoprotein cholesterol to low density lipoprotein cholesterol in LI group was lower than NI group and HI group. The concentration of apolipoprotcin AI of NI group was lower than LI group and HI group. The hematorict of HI group was higher than NI group, and the blood viscosity of HI group was higher than the other two groups. LI group’s plasma apparent viscosity was the highest in groups, next was HI group, and the last was NI group.3.3 The electrocardiogram of different groupsThe abnormal rate of electrocardiogram (ECG) and myocardial injury rate in NI group were lower than the other groups (P< 0.05), while the rate of arrhythmia in HI group was the highest (P< 0.05). There was no difference in the occurance of conduction block and atrioventricular hypertrophy of different groups.3.4 The examination of carotid ultrasound of different groupsThe left carotid artery diameter of LI group was significantly greater than NI group and HI group. The right carotid artery diameter of LI group was the highest in the groups, second was HI group, and the last was NI group. The carotid plaques rate and IMT thickening rate rises with iodine concentration increased, and the two in HI group were higher than LI group. The results showed no difference in hemodynamic index of different groups.3.5 The logistic regression analysis of carotid plaquesRegression analysis showed that the age, smoking, drinking, carotid intima-media thickness, serum triglyceride and cholesterol levels, pulse pressure and the nutritional status of selenium and iodine were the influence factors of carotid plaques. The results showed that smoking, drinking, age over 50, pulse pressure over 60mmHg, and iodine intake over 500ng may be the risk factor for carotid plaques. In addition, the risk increased with the increase of carotid intima-media thickness, serum triglyceride and cholesterol.Conclusions1. There were differences in iodine nutrition of different water iodine regions. Food iodine intake plays an important role in ensuring appropriate iodine nutrition, especially for low water iodine area, and the aquatic product food contributes the most to food iodine intake, accounted for half of the food iodine intake.2. High iodine intake can promote the occurrence of thyroid nodule, the multiple nodules and the nodule boundary unclear ratio were higher and calcification rate has increased with iodine increased. The possibility of deterioration of nodules in HI group is higher.3. Excessive iodine intake can affect the level of blood lipid, and the hematorict and plasma viscosity in HI group was higher than NI group. High iodine intake can increase the risk of cardiac disease, also promote the occurrence of arrhythmia and myocardial injury. The incidence of carotid plaques showed a tendency of increased with iodine concentration, and the incidence in HI group was the highest.4. High iodine may be a risk factor for diseases of heart and vasculature, high iodine may promote the occurrence of disease through the regulation of thyroid hormone and direct damage to blood vessel cells. |
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