There are a number of investigations used in the diagnosis of Graves' disease:
1. Free T3 and T4 LevelsIn classical cases, both T3 and T4 are elevated
2. Serum TSH LevelsSerum TSH levels are classically suppressed.
3. Radioactive Iodine or Technetium ScanThis will show an increased uptake in Graves' disease.
4. Thyroid AntibodiesAutoantibodies against microsomal thyroid cell antigens are present in 90% of cases.