How can lab testing confirm a hyperthyroidism diagnosis?

Laboratory testing to confirm the diagnosis of hyperthyroidism will include thyroid function tests. Usually, the TSH level will be lower than normal and the T3 and/or T4 levels will be higher than normal. Subclinical hyperthyroidism is defined as cases where there are no clear symptoms or physical signs of hyperthyroidism on history and physical examination, but the blood level of TSH is low, and T3/T4 levels are normal.