Are you tired, cold, and can’t lose weight? These symptoms together come through my office almost daily. The most common cause of these symptoms is a low functioning thyroid. Over the next few posts, we will talk about how the thyroid works, how to test it thoroughly and what options correct a low functioning thyroid.
The thyroid gland is a butterfly-shaped organ that resides in the front of the throat. It is the power plant that gets a message from the anterior pituitary gland in your brain to manufacture thyroid hormone as needed via thyroid stimulating hormone (TSH). So if your metabolism is getting sluggish or your internal thermostat is running low, you will produce thyroid hormone to kick these systems into gear.
When we talk about thyroid hormone we are actually talking about a group of hormones. Knowing the individual hormones will allow you to know how to test them properly.
Thyroxine or T4 is the main thyroid hormone made in the thyroid gland. T4 is actually comprised of bound T4 and free T4. It is made in great amounts but it doesn’t do a good job to correct the tired, cold, or overweight symptoms. For that, we need to convert T4 into T3. T3 is also made to a lesser extent in the thyroid gland as well. T3 is also comprised of bound and free T3.
Free T3 is the most active and potent thyroid hormone. It is this thyroid hormone that corrects the tired, cold, and overweight symptoms and is often deficient in a low functioning thyroid. Free T3 is so powerful that in excess it can be toxic.
It’s because of the potentially toxic nature of free T3 that the body has a safety valve called reverse T3. T4 will convert to reverse T3 to protect itself from too much free T3. The problem is when the body coverts too much of T4 to reverse T3 and not enough to free T3.
So when we are testing thyroid function we need to test all these components:
Complete T4 (free and bound)
Complete T3 (free and bound)
Just testing TSH and T4 never gives us the complete picture. Advocate for yourself by getting a complete picture of your thyroid function with these additional tests.