High serum free T4 is generally suggestive of abnormal thyroid function, such as possible hyperthyroidism, or iodine-derived abnormalities.
Hyperthyroidism should be considered when the serum free T4 is elevated at more than 2 times the normal value, or when it is accompanied by elevated free T3 and decreased free TSH; when the free T4 is elevated at less than 2 times the normal value, and the free T3 and free TSH are normal, then the patient has T4-type hyperthyroidism, which is mostly iodine-origin abnormality.
Patients with hyperthyroidism, depending on the patient’s condition, age, and whether or not they are pregnant, choose the appropriate treatment, such as medication, iodine 131 treatment, or surgical treatment. In the case of iodine-derived abnormalities, medication is usually not necessary, a high iodine diet is restricted, and changes in free T4 values are dynamically observed.
If the serum free T4 is abnormal, it is recommended to consult a doctor in time.