The five thyroid function tests refer to the five indicators of thyroid function, namely total thyroxine (TT4), total triiodothyronine (TT3), thyroid stimulating hormone (TSH), free triiodothyronine (FT3), free thyroxine (T4), and they can assist in the diagnosis of whether the thyroid function is abnormal or not. 1. In hyperthyroidism: total thyroxine (TT4), total triiodothyronine (TT3), free triiodothyronine (FT3) and free thyroxine (FT4) are elevated, and thyroid stimulating hormone (TSH) is lowered. 2. In hypothyroidism: total thyroxine (TT4), total triiodothyronine (TT3), free triiodothyronine (FT3) and free thyroxine (FT4) are decreased, and thyroid stimulating hormone (TSH) is increased. If abnormalities in the five thyroid function tests are detected during physical examination, prompt medical consultation should be sought to avoid delaying the condition.