Inclusion Criteria:

1. aged 20 to 75 years

2. under birth control, if fertile women

3. Groups

- who received radioactive iodine treatment for recurrent and metastatic thyroid
cancer, and did not showed any uptake at post-therapeutic whole body scan

- who planned to receive empirical radioactive treatment due to high expected
recurrence

Exclusion Criteria:

- allergic to alpha-lipoic acid

- severe heart failure, lung disease, or end-stage renal disease

- liver function abnormalities (x2.5 above normal limits)

- neuropsychologically unstable patients

- previous history of drug medication such as oral steroid, digoxin, theophylline,
carbamazepine, valproic acid, phenobarbital, methotrexate, cyclosporin, tacrolimus
within 3 months before this recruitment.

- who is already taking alpha-lipoic acid for other purpose.