| Objective Iodine is one of the trace elements to the human beings and the essential component of thyroid hormones. Iodine deficiency or iodine excess will both have adverse effects on the body. To realize the difference of prevalence rate and disease composition of thyroid tumor between iodine-excess area and iodine-normal area by epidemiological survey. To valuate character of age and gender of thyroid tumor especially thyroid cancer, in iodine-excess area. To investigate the factors of the occurrence of thyroid tumor and reasons of high iodine intake in iodine-excess area. To explore the effect of high iodine on people for scientific basis of the treatment and prevention of thyroid tumor in iodine-excess area..Method Based on the historical data and acquired MUI of pupils in pilot investigation, we determined to select NanDaGang of CangZuo City, Hebei, as our destiny. Selected 1575 adult inhabitants was more than 10 years of residence in the local, did not leave the area the last 2 weeks, and without history of radiation exposure before the age of 15 (≥20 year; M 808, F 767;mean age 45.26±18.15)were questioned, then were given further examination. We also measured the iodine amount in the drinking water and iodinized salt. All those given further examination were questioned for detailed thyroid diseases history and taken physical examination, also, their blood and urine samples during morning fast were collected. Urinary iodine was evaluated.Thyroid ultrasouds were also done to the people. The prevalence of thyroid diseases was assessed. We select a iodine-normal area which has similar economic, sanitary, environmental conditions as control region. A total of 400 patients of Tianjin with 200 thyroid benign and 200 malignant tumor seen in our hospital between Aug 2009 and Feb 2010 tumor were detected empty stomach urine iodine concentration by arsenic-cerium catalytic spectrophotometry, meanwhile 200 normal person were set as control group.All these data were input into database and analyzed with SPSS.Results1.The really examined population of resident(2,403) is 1,575(M 808, F 767;mean age 45.26±18.15) in iodine-excess area; The really examined population of resident(2,011) is 1,258(M 640, F 618;mean age 44.21±16.25) in iodine-normal area. The population of two area are similar. MUI of iodine-excess area (439 ug/L) is higher than that of iodine-normal area (198 ug/L) (P<0.05). Iodine concentration higher than 500 ug/L accounts for 41.5% of the sampling crowds, higher than 1000 ug/L accounts for 6.2% in the iodine-excess area. Iodine concentration higher than 500 ug/L accounts for 5.1% of the sampling crowds, higher than 1000 ug/L accounts for 0.0% in the iodine-normal area.452 people in iodine-excess area were diagnosed having thyroid tumor and its prevalence rate was 2869.84 per 10,000, which is 2.10 times higher than that in iodine-normal area. Higher prevalence of thyroid tumor was found across age groups in iodine-excess area. The prevalence of thyroid tumor among females in iodine-excess area was 2.06 times higher than that in iodine-normal area, the prevalence of thyroid tumor among males in iodine-excess area was 2.19 times higher than that in iodine-normal area.2. Thyroid divided into 5 categories:diameter more than 2cm single benign tumor, diameter more than 2cm single benign tumor, the maximum tumor diameter less than 2cm multifocal benign tumor, the maximum tumor diameter less than 2cm multifocal benign tumor, thyroid malignant tumor. All thyroid malignant tumors is PTC. Tumor classification of two area is similar and common types is the maximum tumor diameter less than 2cm multifocal benign tumor (iodine-excess area:73.09%, iodine-normal area:79.28%). In iodine-excess area,the number of patients with thyroid goiter is 395 (12.54%), incluing nodular thyroid goiter(280), diffused thyroid tumor (115).The number of thytoid tumor without goiter is 632.3. MUI of male in iodine-excess area (432 ug/L) is not higher than that of female area (445 ug/L) (P>0.05).266 female people in iodine-excess area were diagnosed having thyroid tumor and its prevalence rate was 3468.04 per 10,000, which is 1.50 times higher than male. Female prevalence rate of thyroid tumor in the 40-year-old age group reached peak and then decline slowly. Male prevalence of thyroid tumor showed a slow increase with age.4.33 people in iodine-excess area were diagnosed having thyroid carcinoma and its prevalence rate was 209.52 per 10,000, which is 13.18 times higher than that in iodine-normal area. Higher prevalence of thyroid carcinoma was found across age groups in iodine-excess area. The prevalence of thyroid carcinoma among females in iodine-excess area was 16.12 times higher than that in iodine-normal area, the prevalence of thyroid carcinoma among males in iodine-excess area was 10.29 times higher than that in iodine-normal area. Female prevalence rate of thyroid carcinoma in the 40-year-old age group reached peak. Male prevalence of thyroid carcinoma showed a slow increase with age. The total patient of thyroid carcinoma in iodine-excess is PTC, including multifocal thyroid carcinoma (21.21%), single thyroid carcinoma (78.79%), the maximum tumor diameter more than 1cm carcinoma(18.18%) and the maximum tumor diameter less than 1cm carcinoma (81.82%).5. The formation of thyroid tumor in iodine-excess area was a result of the action of multiple factors, among which, sex (OR=1.797,95%CI 0.915-3.530), age (OR=2.978,95%CI 0.608-14.592), history of thyroid disease (OR=2.336,95%CI 1.096-4.982), smoking (OR=1.868,95%CI 0.373-9.364), the number of pregnancy (OR=1.572,95%CI 0.668-3.695), contraceptive use (OR=1.326,95%CI 0.682-2.575), breast disease (OR=1.580,95%CI 0.838-2.979), BMI (OR=1.919, 95%CI 0.724-1.9610) and urinary iodine (OR=1.386,95%CI 0.688-2.751) have influence on its formation (P<0.05). Thyroid tumor had no significant relation with income, labour, history of cancer of Immediate family, drinking and tea (P>0.05)6. There is no statistical significant difference between median urinary iodine(MUI) of benign thyroid tumor(519ug/L) and PTC (524ug/L) (P>0.05) in Tianjin cancer hospital,which both are in excessive iodine intake. MUI of the control group without thyroid disease is 196ug/L,in adequate iodine intake, and the two former groups are both higher than it,(P<0.05).7. The median of water iodine of well in iodine-excess is 448.22 ug/L and tap water is 427.15 ug/L.The main type of drinking water is well and tap water(60.68%). The main type of salt in iodine-excess is iodized salt(74.48%),the median of salt intake is 7.2±3.78 per day and people. Iodine intake in iodine-excess had relation with the type of drinking water (OR=2.207,95%CI 0.956-5.096), salt intake (OR=1.743, 95%CI 0.862-3.521),the type of salt (OR=1.925,95%CI 0.989-3.747) and brined vegetables (OR=2.092,95%CI 0.899-4.869)Conclusions 1. The prevalence and incidence of thyroid noeplasm in iodine excessive area are much higher than those in the normal area and MUI of PTC is higher than normal. There may be a relation between high iodine intake and occurrence and development of thyroid neoplasm.2.Prevalence rate of thyroid carcinoma in iodine-excess area is higher than that in iodine-normal area. The total patient of thyroid carcinoma is PTC, of which is mainly single micro-carcinoma. The histological type of thyroid carcinoma seems to shift, presenting as increased PTC incidence and decreased FTC incidence.3.Benign tumor classification of two area is similar and common types is the maximum tumor diameter less than 2cm multifocal benign tumor which can received drug treatment or regularly observation. Rate of tumor with surgical indications is smaller.4.In our study,thyroid tumor has relation with sex, age, history of thyroid disease, smoking, the number of pregnancy, contraceptive use, breast disease, BMI and urinary iodine. The thyroid of risk group should be monitored carefully.5. The finding suggests that intervention measures should be taken to reduce the intake of iodine on the basis of the distribution of water iodine and iodized salt to lower the prevalence rate of thyroid tumor. |
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