the Effect of Universal Salt Iodization on Thyroid Diseases

1. acquire the environmental iodine status of Hangzhou
2. acquire the iodine status of population in Hangzhou
3. acquire the prevalence of thyroid diseases in Hangzhou
4. explore the association between iodized salt and thyroid disease

Inclusion Criteria:

1. age ≥ 6 years old;
2. living for above 5 years at present residence.

Exclusion Criteria:

1. resident with coronary angiography (CAG) or endoscopic retrograde cholangiopancreatography (ERCP) in 6 months;
2. resident taking amiodarone drug;
3. resident with abnormal kidney function or serious illness