Hyperthyroidism is hyperthyroidism. Subacute thyroiditis is not hyperthyroidism, but symptoms of hyperthyroidism can sometimes occur. Subacute thyroiditis is mainly caused by viral infections, immune system abnormalities, etc., which can lead to the destruction of thyroid follicular epithelial cells, further leading to free thyroxine into the bloodstream, which may lead to the manifestation of sexual hyperthyroidism. However, the corresponding disease is not hyperthyroidism, and with the stabilization of the physical condition, some may even develop hypothyroidism. If you have subacute thyroiditis, you need to consult a doctor to confirm the diagnosis of the condition and then carry out standardized treatment under the guidance of the doctor to avoid delays in the condition.