High prevalence of goiter in an iodine replete area: do thyroid auto-antibodies play a role?
BACKGROUND
Despite long standing iodine supplementation in Iran the prevalence of goiter remains high in some areas. This may suggest that causes other than iodine deficiency, such as autoimmune thyroid diseases, should also be considered. We therefore assessed the prevalence of anti-thyroid antibodies in children living in an inland area in Iran and correlated these findings with prevalence of goiter within this region.


METHODS
In a cross-sectional study, 1948 students were selected by multistage random cluster sampling from the 108 primary schools (age, 7-13 year-old) of the urban and rural areas of Semirom. After obtaining written consent from their parents, the children were examined by endocrinologists for goiter grading. Grade 2 goitrous children (108 cases) were compared with non-goitrous children (111 children as control group) for anti-thyroid antibodies.


RESULTS
Overall, 36.7% of 1948 students had goiter. The mean urinary iodine excretion level was 1.49+/-0.7 micromol/L. This was within normal limits. Of 219 children studied, 4.3% presented with subclinical hypothyroidism, and 7.3% had positive anti-thyroid antibodies. There was non-significant difference of positive thyroperoxidase antibody (anti-TPO) (Odds Ratio= 3.2, p= 0.13) but significant difference of anti Tg between goitrous and non goitrous children (Odds Ratio: 5.6, 95% CI: 1.18-26.0, p: 0.015).


CONCLUSIONS
This study suggests that autoimmunity may be one of the mechanisms responsible for goiter persistence after iodine replenishment in this iodine deficient region, but the role of other factors should also be considered.
Hashemipour
Mahin
M
Assistant Professor of Endocrinology, Endocrine and Metabolism Research Center, Isfahan University of Medical Sciences, Isfahan, Iran.
Amini
Masoud
M
Aminorroaya
Ashraf
A
Dastjerdi
Mansour Iavash
MI
Rezvanian
Hassan
H
Kachoei
Ali
A
Moaddab
Mohammad Hassan
MH
Mohammadi
Mohammad
M
Kelishadi
Roya
R
Amini
Zhale
Z
Haghighi
Sassan
S
Shojaee-Moradie
Fariba
F
D000293:Adolescent; D001323:Autoantibodies / Q000097:blood* / Q000276:immunology; D016022:Case-Control Studies; D002648:Child; D016000:Cluster Analysis; D016001:Confidence Intervals; D003430:Cross-Sectional Studies; D005260:Female; D006042:Goiter / Q000453:epidemiology* / Q000209:etiology; D006801:Humans; D007453:Iodide Peroxidase / Q000378:metabolism; D007455:Iodine / Q000008:administration & dosage* / Q000172:deficiency / Q000652:urine; D007492:Iran / Q000453:epidemiology; D008297:Male; D016017:Odds Ratio; D015995:Prevalence; D017673:Sodium Chloride, Dietary / Q000008:administration & dosage; D013967:Thyroiditis, Autoimmune / Q000453:epidemiology*
D001323:Autoantibodies; D017673:Sodium Chloride, Dietary; C034024:iodized salt; D007455:Iodine; D007453:Iodide Peroxidase