Non-immune Related Hypothyroidism in Iodine Sufficient Area
Non-immune Related Hypothyroidism in Iodine Sufficient Area
Background: Autoimmune hypothyroidism has been regarded as the most common cause of primary
 hypothyroidism in iodine sufficient area and has relationship with excess iodine induced
 hypothyroidism. However, non-immune related hypothyroidism and its relationship with excess
 iodine have been rarely evaluated.

 Objective: Therefore, the investigators planned to calculate proportion of non-immune related
 hypothyroidism and relationship with iodine intake using nationwide data from Korea National
 Health and Nutrition Examination Survey (KNHANES) 2013-2015.

 Design:

 1. Korea National Health and Nutrition Examination Survey VI (2013 to 2015) - The national
 data - which is the government designated statistics (Approval No. 117002 ) of South
 Korea based on the Article 17 of the National Health Promotion Act - were used. The
 survey was approved by the Institutional Review Board of the Korea Centers for Disease
 Control and Prevention, and provides only non-identified measures for academic research
 purposes.

 2. The participants who were examined for thyroid stimulating hormone, free thyroxine,
 thyroid peroxidase antibody (TPO Ab), and urine iodine concentration (UIC) were
 included.

 3. The proportion of immune related and non-immune related hypothyroidism was evaluated.
 Demographic variables and severity of hypothyroidism were compared between the two
 groups. To analyze iodine effect on hypothyroidism in TPO Ab positive or negative
 population, prevalence of hypothyroidism were assessed in each TPO Ab negative and
 positive population according to UIC subgroups.

 4. This study protocol was approved by IRB of SMC (2017-05-149).
Inclusion Criteria:

 -  examined for thyroid stimulating hormone, free thyroxine, thyroid peroxidase antibody
 (TPO Ab), and urine iodine concentration (UIC)

 Exclusion Criteria:

 -  already have a thyroid disease(benign thyroid diseases or thyroid cancer).