Effects of iodized salt consumption on goiter prevalence in Isfahan: the possible role of goitrogens

Knowledge, attitude, and practice of iodized salt use in Al-Riyadh and Al-Ozozab areas, Khartoum, Sudan

Iodine deficiency and subsequent iodine deficiency disorders have been a longstanding problem in many areas of the world, including Sudan, and still remains as the leading cause of preventable brain damage. According to the Sudan Household Health Survey, in 2006, the consumption of iodized salt in Sudan was 11%, only to deteriorate later on in 2011 to 9.5%. This is a descriptive cross sectional study which assesses the knowledge, attitude, and practice regarding the use of iodized salt in two socioeconomically different residential areas, Al-Riyadh and Al-Ozozab, Khartoum city, Sudan. From total of 152 participants selected from Al-Riyadh and Al-Ozozab areas (50% from each), there were 87 (57 %) females. Participants from Al-Riyadh had a higher educational and income level than those from Al-Ozozab, and better knowledge regarding the importance of regular iodized salt consumption to treat iodine deficiency (61% and 54%, respectively). However, only 39% of the participants were actually buying iodized salt. There was a significant relationship between residency and buying of iodized salt among the participants from Al-Riyadh (49%) and Al-Ozozab (30%) areas (p-value = 0.02). There was also significant association between the educational level and buying iodized salt (p-value = 0.014), but not with the income (p-value = 0.23). The consumption of potential goitrogenic foods (pearl millet or peanut butter) was high among the participants (n = 142) from Al-Riyadh and Al-Ozozab, and constituted 76% and 83%, respectively. Compulsory national salt specification needs to be established in Sudan, together with monitoring the market availability of iodized salt.

Incidence of thyroid dysfunction in an Iranian adult population: the predictor role of thyroid autoantibodies: results from a prospective population-based cohort study

Background

The prevalence of thyroid dysfunction is high in Isfahan, an area of iodine sufficient in Iran. The aim of this study is to investigate the incidence of thyroid dysfunctions in adults of metropolitan Isfahan and to determine the role of thyroid autoantibodies.

Methods

In a population-based cohort study in 2006–2011, we measured TSH, T4, T3, thyroid peroxidase antibody (TPOAb), and thyroglobulin antibody (TgAb) in 618 out of 2254 people who were euthyroid in 2006. The incidence rates per 1000 person-year (pr) were calculated. The odds ratio (OR), relative risk (RR), and 95% confidence interval (95% CI) were calculated based on logistic regression to quantify the potential predictors of thyroid dysfunction. The receiver-operator characteristic (ROC) analysis along with area under the curve (AUC) was used to determine the optimal cutoff values for baseline TPOAb and TgAb as predictors of thyroid dysfunction.

Results

Within a 6-year follow-up, the incidence rate of hypothyroidism was 3.3 in women and 2.1 in men while the incidence rate of hyperthyroidism was 3.8 in women and none in men per 1000 (person-year). A cutoff value of TPOAb at 38 IU/mL was obtained to differentiate the patients with hypothyroidism and hyperthyroidism, with specificity of 0.75 and sensitivity of 0.76, and AUC (CI 95%) of 0.882 (0.743–1.02), P = 0.01 and 0.817 (0.600–1.035) P = 0.033, respectively. There is a statistically significant association of hypothyroidism and hyperthyroidism with positive TPOAb [RR (CI 95%): 1.99 (1.27–3.13) and 2.20 (1.23–3.95), respectively].

Conclusions

The incidence rate of thyroid dysfunction is high in Isfahan, and higher TPOAb concentration is its strong predictor.

The TSH levels and risk of hypothyroidism: Results from a population based prospective cohort study in an Iranian adult's population

OBJECTIVE

The aim of current study was to assess the relationship between serum TSH levels and hypothyroidism risk in the euthyroid population.

METHODS

In a population-based cohort study, a total of 615 individuals with a normal baseline TSH, from of total population (n=2254) in 2006, were followed up for 6years. TSH, total T4, thyroid peroxidase antibody (TPOAb), and thyroglobulin antibody (TgAb) were measured. The relative risk (RR) and 95% confidence interval (95%CI) were calculated based on logistic regression. The Receiver Operating Characteristic (ROC) analysis along with area under the curve (AUC) was used to prediction of future hypothyroidism.

RESULTS

TSH level in 2006 was a significant predictor for overt hypothyroidism, in the total population (RR=3.5) and female (RR=1.37) (all, P value<0.05). A cutoff value of TSH at 2.05mIU/L [AUC: (CI95 %), 0.68 (0.44-0.92; P=0.05)] was obtained for differentiating the patients with overt hypothyroidism from euthyroid. However, this cut off was not observed when we included only negative TPO and TgAbs people in 2006. The RR of hypothyroidism increased gradually when TSH level increased from 2.06-3.6mIU/L to >3.6mIU/L in the total population and both sexes. In women, the risk of overt hypothyroidism was significantly higher in subjects with TSH above 3.6 than those subject with THS levels≤2.05 [RR: (CI95 %), 20.57(2.-207.04), P value<0.05].

CONCLUSION

A cutoff value of TSH at 2.05mIU/L could predict the development of overt hypothyroidism in future. However, it was not applicable for people with negative TPOAb and negative TgAb.

Urinary iodine concentration (UIC) could be a promising biomarker for predicting goiter among school-age children: A systematic review and meta-analysis

OBJECTIVES

To evaluate whether urinary iodine concentration (UIC) can predict goiter among school-age children, and to assess the association between UIC and goiter prevalence.

METHODS

We searched the MEDLINE, EMBASE, Cochrane Library (Cochrane Database of Systematic Reviews), Web of Science, CNKI, VIP, and Wan Fang databases for relevant reports in both English and Chinese up to August 25, 2016. The mean differences (MD) and 95% confidence intervals (CI) were calculated for the UIC and goiter prevalence assessments. Pooled odds ratios and 95% CIs were used to compare the prevalences of goiter in the different UIC groups.

RESULTS

We identified 11 case-control studies, and found that children with goiter had lower UIC values, compared to children without goiter (MD: -1.82, 95% CI: -3.24, -0.40, p < 0.05). An increased risk of goiter was associated with UIC values of < 20 μg/L or > 200 μg/L.

CONCLUSION

The results of our meta-analysis suggest that lower UIC values were associated with an increased risk of goiter, and that iodine deficiency may lead to an increased risk of goiter. Furthermore, we observed U-shaped relationships between UIC and the prevalence of goiter, which suggests that both severe iodine deficiency and excessive iodine intake may lead to increased risks of goiter.

Serum zinc levels and goiter in Iranian school children

Iodine deficiency has been shown to have high prevalence in Iran despite sufficient iodine supplementation. Zinc deficiency may also contribute to the pathogenesis of endemic goiter. The aim of this study was to compare serum zinc level in Iranian school children with and without goiter. A cross-sectional study was performed among urban children aged 8-12 years in city of Kerman, Iran. A multistage proportional to size cluster sampling method was used to screen 5500 subjects out of 29,787 students. After the screening phase, serum and urine specimens of randomly selected 165 students were evaluated for serum zinc levels and urinary iodine excretion and compared in goiterous and non-goiterous children. Serum zinc level was 149.5±29.4 μg/l in goiterous children and 141.2±52 μg/l in non-goiterous children but no significant difference was found between the groups (p=0.37). But urinary iodine excretion was significantly (p<0.001) lower in goiterous children (207.5 μg/l in goiterous children and 262.5 μg/l in non-goiterous children). This study showed that serum zinc level in goiterous and non-goiterus children is not different and zinc deficiency is not a risk factor for endemic goiter in this population.

Thiocyanate status does not play a role in the etiology of residual goiter in school children of Isfahan, Iran

BACKGROUND

Despite long standing iodine supplementation in Iran the prevalence of goiter remains high in some areas. In the present study we investigated the possible role of thiocyanate as a goitrogen in the etiology of goiter in Isfahan, Iran.

METHODS

A total of 2331 (6-13 year old) school children were selected by multistage random sampling. Thyroid size was estimated in each child by inspection and palpation. Urinary iodine concentration (UIC) and urinary thiocyanate (USCN) were measured.

RESULTS

Overall, 32.9% of the 2331 students had goiter. The median UIC was 195.5 μg/L. The mean ± SD of USCN in goitrous and nongoitrous subjects was 0.42 ± 0.28 mg/dL and 0.41 ± 0.32 mg/dL, respectively (P=0.86). USCN level in goitrous and nongoitrous boys was 0.41 ± 0.32 mg/dL and 0.43 ± 0.37 mg/dL, respectively (P=0.67). USCN level in goitrous and nongoitrous girls was 0.43 ± 0.26 mg/dL and 0.40 ± 0.28 mg/dL, respectively (P=0.43).

CONCLUSIONS

Thiocyanate overload does not play a role in high prevalence of goiter in the studied population. We suggest the role of other goitrogenic factors should be investigated in this region.

The role of thyroid autoantibodies in the etiology of endemic goiter in schoolchildren of Isfahan, Iran

BACKGROUND

Eleven years after the initiation of universal salt iodization program in Iran, the prevalence of goiter is still high in some areas.

AIM

To investigate the role of thyroid autoimmunity in the etiology of residual goiter in schoolchildren of Isfahan, Iran.

MATERIAL AND METHODS

In a cross-sectional study, 2331 schoolchildren were selected by multi-stage random cluster sampling. Thyroid size was estimated in each child by inspection and palpation. Urinary iodine concentration (UIC), serum anti-thyroperoxidase antibody (anti-TPO Ab), and anti-thyroglobulin antibody (Anti-Tg Ab) were measured.

RESULTS

Overall, 32.9% of children had goiter. The median UIC was 1955.5 microg/dl. There was significant difference in prevalence of positive anti-TPO Ab in goitrous (grade 2) and non-goitrous children (9.7 vs 3.7%, p= 0.02). Goitrous children had higher prevalence of positive anti-Tg Ab than non-goitrous ones (15.1 vs 3.1%, p<0.001).

CONCLUSIONS

According to the present study, goiter is still a public health problem in this region. This study suggests that thyroid autoimmunity is among the contributors of goiter persistence after elimination of iodine deficiency in Isfahan.

Iodine deficiency among hypothyroid patients living in Jeddah

The objective was to determine the prevalence of iodine deficiency among hypothyroid patients and the effect of dietary goitrogens on indices of iodine and thyroid status. This is a case-control study of 106 subjects who were recruited from King Abdulaziz University Hospital, Jeddah. Blood and urine were collected for serum thyroid hormones, thyroid autoantibodies, thyroglobulin (Tg) and urinary iodine concentration (UIC). Dietary iodine and goitrogenic food intake were assessed by questionnaire. Using World Health Organization (WHO) cutoff values for UIC, both controls and cases were iodine deficient (85% and 83%, respectively). Furthermore, dietary iodine was deficient in 23% of controls and 36% of cases. In cases, there was a positive association between UIC levels and serum thyroid stimulating hormone (r = 0.405, p < 0.01) and a negative association with serum fT(4) (r = -0.358, p < 0.01). Serum Tg antibody titers were also positively associated with dietary iodine (r = 0.328, p < 0.05). Patients with elevated serum autoantibodies had lower UIC and dietary iodine than those with normal serum autoantibodies. UIC was associated with dietary goitrogens including turnip (r = 0.280, p < 0.05) and pine (r = 0.289, p < 0.05) among cases. Iodine deficiency is common and the consumption of dietary goitrogens is high among euthyroid and hypothyroid subjects living in Jeddah.

Selenium deficiency as a possible contributor of goiter in schoolchildren of Isfahan, Iran

The prevalence of goiter still remains high in some areas of Iran in spite of iodine supplementation. In the present study, we investigated the role of selenium (Se) deficiency in the etiology of goiter in Isfahan. Two thousand three hundred thirty-one schoolchildren were selected by multistage random sampling. Thyroid size was estimated in each child by inspection and palpation. Urinary iodine concentration (UIC) and plasma Se were measured. Overall, 32.9% of the 2,331 children had goiter. The median UIC was 19.55 microg/dl. Plasma Se was measured in 96 goitrous and 72 nongoitrous children. The mean +/- SD of plasma Se in goitrous and nongoitrous children was 66.86 +/- 21.82 and 76.67 +/- 23.33 microg/l, respectively (P = 0.006). Goitrous girls had lower plasma Se level than nongoitrous girls (65.62 +/- 21.64 vs. 76.51 +/- 22.61 microg/dl, P = 0.02). Goitrous boys had lower plasma Se level than nongoitrous boys (68.45 +/- 22.21 vs. 76.91 +/- 24.76 microg/l, P = 0.14). The prevalence of Se deficiency was significantly higher in goitrous boys and girls than nongoitrous children. Se deficiency is among the contributors of goiter in Isfahan goitrous schoolchildren. However, the role of other micronutrient deficiencies or goitrogens should be investigated in this region.

Vitamin A status does not contribute to the residual goiter in schoolchildren of Isfahan, an iodine replenished area

Two thousand three hundred and thirty-one schoolchildren were selected by multi-stage random sampling. The thyroid size was estimated by inspection and palpation. The urinary iodine concentration and serum retinol (SR) were measured in 454 and 468 schoolchildren, respectively. Overall, 32.9% of 2,331 children had goiter. The median urinary iodine concentration was 195.5 microg/l. The mean+/-standard deviation of SR in goitrous and non-goitrous children was 34.84+/-7.28 microg/dl and 33.73+/-7.87 microg/dl, respectively (P=0.14). There was no child with vitamin A deficiency (SR <20 microg/dl) in both the goitrous and non-goitrous groups. The prevalence of subjects with low vitamin A status (SR <30 microg/dl) in the goitrous and non-goitrous groups was 27.7% and 33.3%, respectively (P=0.21). In conclusion, the present study reveals that vitamin A deficiency and low vitamin A status are not among the contributing factors of goiter persistence in the studied area, and the role of other responsible factors should be investigated.

Risk factors for goiter in primary school girls in Qom city of Iran

OBJECTIVE

Goiter is endemic in Iran. The iodine deficiency disorders program was begun a few years ago in Iran, and the coverage of iodized salt is sufficient now. But, in a periodic yearly medical examination of primary school girls in Qom, the prevalence of goiter was above 30% in 2002. This survey was designed to study the risk factors of goiter in those students.

DESIGN

The study was a randomized (multistage, proportional simple random sampling) case-control study.

SUBJECTS AND INTERVENTIONS

We selected and performed thyroid examinations in 1050 girl students in primary schools in Qom city of Iran in 2002. We found 284 cases: girls in primary schools had goiter in accordance with the clinical exam of World Health Organization classification. Among students who did not present with goiter in the clinical exam, we randomly selected 288 students as the control group. We used a questionnaire to evaluate them for the risk factors of goiter.

RESULTS

The mean+/-s.d. ages of cases and controls were 8.7+/-1.3 and 8.9+/-1.3 years, respectively. There is no significant difference between the two groups regarding history of soya, kale, turnip, fish, daily iodized salt usage, education and job of mothers, monthly family income, nationality, immigration and residential situation. By using multinomial logistic regression, we found that storage of iodized salt in open containers, odds ratio (OR): 2.201 (1.412-3.428); P-value <0.0001, medium socioeconomic situation (SES) of family, OR: 2.099 (1.029-4.282), P-value=0.041, district 2 of Qom city, OR: 2.880 (1.376-6.027), P-value=0.005, and district 3 of Qom city, OR: 2.051(1.032-4.078), P-value=0.041, were the major risk factors for goiter in this population.

CONCLUSIONS

In this study, the main risk factors for goiter were storage of iodized salt in open containers, medium SES and also living in specific districts of Qom city. As the coverage of iodinized salt is over 95% in Iran, we advise the education of the family about storage of iodized salt in closed containers. We also recommend the study of the other risk factors of goiter in the different geographical areas of Iran, because of differences in the SES and nutritional habits.

SPONSORSHIP

This study was supported by issuing permission letters for our activities: (not funding support) Qom Health Network and Medical Services, Qom Medical University, Qom Primary School Education Office, Fathemieh Medical University.

Iodine repletion, thyrotoxicosis and atrial fibrillation in Isfahan, Iran

BACKGROUND

Iodized salt was reintroduced in Iran in 1989. Just before distribution of iodized salt, thyrotoxicosis was observed in 3.7% of the patients with atrial fibrillation (AF) in university teaching hospitals in Isfahan, a centrally located city in Iran. As repletion of iodine may increase the rate of autoimmune thyroid diseases and toxic multinodular goiter, this study was designed to evaluate the rate of thyrotoxicosis in patients with AF in the same hospitals after about a decade of iodized salt consumption.

METHODS

In a case-control study with convenience sampling, 100 patients with AF and an equal number of age- and sex-matched subjects taking the same medications were selected as case and control groups, respectively, in university hospitals in 1997.

RESULTS

Eight percent of patients with atrial fibrillation had overt thyrotoxicosis versus one percent in the control group (odds ratio=8.6, 95% CI = 6.5 to 10.7, P<0.02). Thyrotoxicosis in patients with AF was 8 times higher than in the control group without AF. In comparison with the period before use of iodized salt, AF more than doubled (8% vs. 3.7%).

CONCLUSION

Thyroid function should be evaluated in all patients older than 40 years of age with AF. The benefits of iodine supplementation are great, but more attention should be paid to the complications of iodine repletion, including thyrotoxicosis and its frequent accompaniment, AF.

Comparison of Urinary Iodine Excretion in Neonates and Their Mothers in Isfahan, Iran

OBJECTIVE

To determine the urinary iodine excretion of neonates (28 days of age or younger) and their mothers in Isfahan, a centrally located city in Iran, in 1997 after 8 years of iodized salt distribution in an effort to ameliorate iodine deficiency.

METHODS

Through a cross-sectional study and by means of convenient sampling, 146 mother-neonate pairs were selected among neonates born in Shahid Sadoughi Hospital in Isfahan. In order to eliminate the effect of povidone-iodine on breast milk and urinary iodine, Savlon antiseptic solution was used in normal vaginal delivery and on the umbilical cord. Normal values of urinary iodine concentration for the mothers and their neonates were > or = 10.0 microg/dL and >5.0 microg/dL, respectively. The data were analyzed and compared by the Student t test and Pearson correlation coefficient in SPSS software. P values <0.05 were considered statistically significant.

RESULTS

In only 3% of the neonates and 14% of the mothers, urinary iodine excretion was below the normal range. No mother or neonate had severe iodine deficiency. In 2% of the mothers and 2% of the neonates, mild iodine deficiency was found. The mean urinary iodine concentration of neonates whose mothers were iodine deficient was significantly lower than that of neonates whose mothers were iodine sufficient (17.34 +/- 7.83 microg/dL versus 22.21 +/- 7.57 microg/dL; P<0.01). A direct significant correlation was noted between the urinary iodine excretion of neonates and that of their mothers (r = 0.37; P<0.01).

CONCLUSION

The urinary iodine excretion in mothers paralleled the urinary iodine concentration of their neonates. If urinary iodine concentration is considered an index of total body iodine content, this study demonstrated that prolonged iodized salt intake has minimized the occurrence of iodine deficiency in Isfahan.