Low free thyroxine generally occurs in hypothyroidism patients. Free T3 and free T4 are thyroxines that play a direct role in the body. If FT3 and FT4 are low in the five items of A function, TSH will often increase, which is a manifestation of primary hypothyroidism. If FT3 and FT4 are reduced, but TSH is normal, there are many reasons for this situation. The most common one is called low T3 syndrome. This is because the iodine intake is insufficient under such weak circumstances, which affects the synthesis of thyroxine, which is only a compensatory reaction of the body. If the TSH value is low, FT3 and FT4 are also low, it may be that there is a central hypothyroidism, or it needs to make a judgment based on the patient's physical condition to decide whether to carry out intervention treatment.
