1. The incidence of differentiated thyroid cancer is increasing in Korea. A significant number of them experience severe hypothyroidism in preparation for radioactive iodine (RAI) therapy after total thyroidectomy.
2. Because the function of thyroid hormone is closely linked with lipid and glucose metabolism, overt hypothyroidism after thyroid hormone withdrawal during RAI therapy may induce the changes of metabolic parameters.
3. We investigate the effects of thyroid hormone withdrawal on metabolic and cardiovascular parameters during radioactive iodine therapy in differentiated thyroid cancer.

1. Study design measurement of various parameters during hypothyroid state (before 1 month, the day and after 1 month of RAI therapy)

2. Measurements

   1. Measurement of metabolic and cardiovascular parameters

      • glucose profiles : HbA1c, fasting glucose level
      • lipid profiles : free fatty acid, total, LDL-, HDL-, cholesterol, triglyceride
      • adipocytokines : retinol binding protein(RBP)
      • 4, leptin, resistin, adiponectin
      • markers of endothelial and cardiac function : high-sensitivity C-reactive protein(hsCRP), homocystein, B-type natriuretic peptide(BNP)
      • bone turnover markers : CTX, bone ALP

   2. Scoring of symptoms and signs of hypothyroidism (Zulewski score)

      • symptoms
      • physical signs

Inclusion Criteria:

• radioiodine therapy after total thyroidectomy in differentiated thyroid cancer
• age over 18

Exclusion Criteria:

• kidney failure, liver failure, heart failure
• infection
• inflammation
• autoimmune disease
• other chronic disease

the patients who experience severe hypothyroidism after thyroid hormone withdrawal for radioiodine therapy in differentiated thyroid cancer