Thyroid function T3 not high T4 high, may be physiological factors, may also be disease factors, such as hyperthyroidism, subacute thyroiditis, etc., also need to be combined with other indicators such as TSH comprehensive judgment. 1. Physiological factors: age, testing time and other factors may lead to T3 is not high T4 high, no need to intervene, regular review of thyroid function can be. 2. Hyperthyroidism: the thyroid gland’s own pathology, caused by the release of excessive thyroid hormone secretion, may lead to an increase in T4, T3 is not high T4 high situation, can be seen in the T4-type hyperthyroidism. 3. Subacute thyroiditis: Due to the destruction of thyroid follicular cells caused by inflammation, the thyroid hormones stored in them are released into the bloodstream, which may result in an increase in T3 but not T4. If thyroid function test results are abnormal, it is recommended to follow the doctor’s instructions to further improve the examination, with the help of the doctor to clarify the cause, and to carry out targeted treatment.