Free Thyroxine Index

A high Free Thyroxine Index (FTI) might mean that your thyroid gland is working too hard, which is called hyperthyroidism. This can happen if your thyroid is making more T4 hormone than your body needs to turn food into energy. There are a few reasons this could be happening, like inflammation in your thyroid gland, growths on your thyroid that make too much hormone, or even certain medications or supplements that boost thyroid hormone production. Keep in mind that everyone's health is different, so this is just a general idea of what high FTI levels could mean.

Symptoms of high levels of FTI could include rapid heart rate, unexplained weight loss, increased appetite, nervousness, irritability, tremors, and excessive sweating.

A low Free Thyroxine Index (FTI) might mean that your thyroid gland isn't making enough of the hormone thyroxine (T4), which is important for turning the food you eat into energy. This situation, called hypothyroidism, can happen for various reasons such as stress, not getting enough nutrients, or your body mistakenly attacking your thyroid gland (an autoimmune response). Some medications, like lithium or amiodarone, can also affect your thyroid's ability to make T4. Additionally, conditions like Hashimoto's thyroiditis, a common cause of hypothyroidism, could be playing a role. Keep in mind that this is a general explanation and individual situations can be different.

Symptoms of low levels of FTI may include fatigue, weight gain, feeling cold, dry skin, hair loss, and slowed heart rate. Cognitive changes such as difficulty concentrating or memory problems could also be experienced.