The function of the thyroid gland is typically assessed through a single measurement called Thyroid Stimulating Hormone, also known as TSH. TSH can indicate that something is wrong with the thyroid gland if it is too high or too low. If the TSH level is very high this can indicate hypothyroidism, an under active thyroid. If the TSH level is very low this can indicate hyperthyroidism, an over active thyroid.
Why TSH may not be enough
It is possible that your TSH may be considered to be within the normal range, but your thyroid is not functioning optimally. What if your TSH was 2.0 three years ago, 3.1 last year and 3.8 now? Most labs consider TSH above 4.0 an elevated level so in this situation you may be told that your thyroid function is fine and there is no need to treat or to investigate further. But waiting until lab values catch up to symptoms is not the way to prevent dysfunction and disease. If you are experiencing signs and symptoms of hypothyroidism a more comprehensive look at the other thyroid hormones may provide more detail and treatment options.
Comprehensive thyroid testing
If you are experiencing some of the signs and symptoms of a thyroid disorder, testing beyond TSH can give a more comprehensive look at how the thyroid is functioning. This can help identify an issue in thyroid function before TSH is out of range and help you take charge of your symptoms and body before the issue progresses.
Depending on the individual, additional testing I recommend may include:
The most active of the thyroid hormones. TSH and T4 levels can be normal but T3 levels can be low. Since T3 is the hormone that is most active, a low T3 will result in hypothyroid symptoms. If just TSH or T4 are tested this may be missed.
The most abundant of the thyroid hormones. T4 is produced in much larger quantities than T3 and converted to T3 in our tissues. If you have low T4 levels but normal T3 this could be a sign that your body isn’t producing enough T4 and struggling to convert into the more active T3 hormone.
Anti-TPO & Anti-TG
Both of these are antibodies that are elevated in autoimmune hypothyroidism (also known as hashimotos hypothyroidism). Hashimotos is the most common cause of hypothyroidism in North America. Read more about Hashimotos here.
In states of chronic disease and stress the body converts the active free T3 hormone to the inactive reverse T3. If free T3 is low and reverse T3 is high this could be an indication that chronic stress is impacting the function of the thyroid.
The above are just some of the tests I recommend specific to the thyroid. Keep in mind that there are may other aspects that affect the function of the thyroid. Read about the minerals that are essential for proper thyroid function here.