What does free thyroid mean

When some people go to the hospital for a check-up, they are told that their free thyroid is high or low. In fact, this is an abnormal phenomenon and may be closely related to hyperthyroidism. Therefore, if the free thyroid is found to be abnormal, the doctor will generally ask the patient to undergo a detailed physical examination to confirm whether it is caused by hyperthyroidism. If so, treatment should be taken.

Free thyroxine (FreeThyroxineIndex.FT4I) is the main part of the biological effect of this hormone. Although FT4 accounts for only 0.025% of T4 and FT3 accounts for only 0.35% of T3, they are closely related to the biological effects of thyroid hormones, so they are the preferred indicators for diagnosing clinical hyperthyroidism. Many hospitals have used these two indicators instead of TT4 and TT3 to diagnose hyperthyroidism.

Thyroid hormones are synthesized, stored, and released by the thyroid gland. The raw materials for synthesizing thyroid hormones are iodine and tyrosine in the body. Under normal dietary conditions, the human body consumes 100 to 200 micrograms of iodine every day. Iodine absorption from the intestine is complete. Iodine in the diet is first converted into iodide in the intestinal mucosa and then absorbed; the skin, mucosa and lungs can also absorb iodine, but the absorption is much worse than that in the intestines. Iodine absorbed by the intestine is mainly distributed in the extracellular fluid. The iodide concentration in serum is 0.5 microgram%. The thyroid gland has the ability to concentrate iodine. The iodine concentration in the thyroid gland is 20 to 40 times higher than that in the blood.

The concentration capacity of patients with hyperthyroidism can increase 100 to 200 times. The salivary glands and the thyroid gland both originate from the foregut, so they also have the function of concentrating iodine. The normal salivary iodine/serum iodine ratio is 20. In clinical practice, the thyroid gland's ability to concentrate iodine can be easily determined by measuring the iodide content in the salivary glands. In addition to the salivary glands, other glands in the body have the ability to concentrate iodine to a similar extent as the thyroid gland. Under normal circumstances, iodine in saliva and gastric juice is reabsorbed through the digestive tract and returned to the extracellular fluid.

Through the above introduction, I believe everyone has a certain understanding of what free thyroid means. In fact, free thyroxine reflects the health of the thyroid gland. If the free thyroxine is low, the body will not be able to absorb iodine, causing thyroid disease, which requires treatment.