Laboratory investigations include the following:

I. Thyroid Function test

  • Serum TSH level: TSH levels are decreased in hyperthyroidism
  • Serum T4 level: Serum T4 is increased
  • Serum T3 level: Serum T3 is increased
  • Resin T3 uptake test: Resin T3 uptake is increased
  • Radioactive iodine uptake test: Radioactive iodine uptake is high in hyperthyroidism

II. TSH receptor antibody (TSH-R Ab): It is high in 80% of cases.

III. Other blood test:

  • Increased blood calcium level (hypercalcemia) and alkaline phosphatase
  • Increased ESR (Erythrocyte sedimentation rate) in thyroiditis

IV. Electrocardiogram (ECG or EKG) and Echocardiography (ECHO) may be required in case of heart involvement.