What is T4 Free Thyroxine?

T4 free thyroxine is a measurement of the free thyroxine, i.e. the thyroxine that is not bound to proteins in the blood. T4 is a thyroid hormone that is important for regulating body temperature and metabolism. Too high or too low a level of T4 can indicate thyroid problems such as hyperthyroidism or hypothyroidism.

Why is T4 Free Thyroxine analyzed?

It can be useful to analyze your levels of free T4 through a blood test as it gives a more accurate picture of how much thyroxine is available for the body to use. When thyroxine is measured in the blood, some of it may be bound to proteins, rendering it useless to the body. Free T4 measures the thyroxine that is not bound to proteins and is therefore more accurate in determining how much thyroxine is available to the body.

Another advantage of measuring free T4 is that it can help distinguish between different types of thyroid problems. For example, if the TSH (thyroid-stimulating hormone) level is high, it may indicate hypothyroidism, but if the free T4 level is normal, it may indicate that the problem is in the hypothalamus or pituitary gland instead of the thyroid gland.

Another reason to measure free T4 is that it can help monitor the treatment of thyroid problems. When a person is being treated with drugs for hypothyroidism or hyperthyroidism, it may be important to measure free T4 to ensure that the treatment is effective and that there is a normal level of thyroxine in the body.

Overall, measurement of free T4 provides more accurate and relevant information about thyroid hormone production and can help the doctor make an accurate diagnosis and choose the right treatment.