Why TSH Alone Isn’t Enough to Properly Assess Thyroid Function

Have you ever been told that your thyroid function is normal since your TSH is within the "normal range"? Or maybe your TSH is higher than the range stated on the lab report, but it's not "high enough" to initiate treatment, so you're told to watch and wait.

Whether you're having symptoms but your TSH appears to be "normal," or if your TSH is high but you're not comfortable with the watch and wait approach, there's more to the puzzle, and there's a lot we can (and should) look into, to help you feel like yourself again!

What Does the Thyroid Do?

The thyroid is a butterfly-shaped gland located at the base of the neck. The thyroid gland gets a signal from the brain to produce hormones called T3 and T4. These thyroid hormones play a role in the metabolism of organs and tissues throughout the entire body — heart, adipose tissue, bones, muscles, nervous system, gut, reproductive organs, etc. If this signalling pathway is not working properly, it can result in our thyroid producing too much or too little thyroid hormones, which leads to a variety of systemic symptoms since these hormones play such a vital role in the metabolism of every single cell in our body.

Since every cell in our body is dependent on thyroid hormones to regulate its metabolism, you can imagine the wide range of symptoms that could result from a thyroid that is under or over-functioning. If the thyroid is under-functioning (hypothyroidism), common symptoms someone may experience are fatigue/exhaustion, constipation, sensitivity to cold, dry skin, hair thinning, and weight gain; however, these may vary from person to person. For a more comprehensive list of symptoms for both hypothyroidism and hyperthyroidism, click here.

What is TSH and is it Helpful?

TSH, or "thyroid-stimulating hormone," is a blood test that gives us great insight into how the thyroid is functioning. However, to get the most out of its interpretation, it should be used in conjunction with other thyroid markers (free T3, free T4, and thyroid antibodies). Whether someone's hypothyroidism is autoimmune in nature or not, TSH will likely be elevated at some point during the disease process. This is why TSH is not enough to assess thyroid function on its own. Seeing an elevated TSH in isolation from other thyroid markers does not give us insight into the cause of the hypothyroidism.

What Other Thyroid Tests Should We Look At?

thyroid antibodies

Antibodies (anti-TPO and anti-thyroglobulin) should be tested to assess the cause of the hypothyroidism, as their presence rules in Hashimoto's thyroiditis (autoimmune hypothyroidism).

thyroid hormones (free t3 & t4)

There may also be instances where, after initiating medication, a person’s TSH normalizes but they still experience symptoms (fatigue, brain fog, etc.). This is where testing thyroid hormones (FT3 and FT4) would be beneficial in order to understand where their thyroid needs more support.

nutrient levels

For a thorough and comprehensive assessment, nutrients that impact the thyroid should also be considered, such as iron and vitamin D. Iron deficiency can be found in up to 60% of people with hypothyroidism, and anemia can be seen in 30% of individuals with Graves’ disease (autoimmune hyperthyroidism). Higher levels of vitamin D deficiency have been seen in those with thyroid dysfunction.

You can see with these few examples how testing thyroid hormones, thyroid antibodies, and nutrients that impact the thyroid, in addition to TSH gives a more individualized, well-rounded picture of someone's thyroid health.

A Final Word

Overall, TSH is a useful blood test when it comes to assessing and monitoring the thyroid, however, it is important to note that TSH is not the only valuable test out there. It is crucial to establish the cause of your thyroid imbalance, assess possible deficiencies of nutrients that impact thyroid function, and most importantly, assess how you are feeling — are your symptoms improving, or worsening?

Looking For More Support?

If you are unsure if your thyroid is being properly assessed or monitored, and would like more guidance, there is so much we can do to support you! If you want to learn more about how naturopathic medicine can improve your thyroid health, you can read more about that here. You can reach out to us for more information or book a complimentary consult with me here!