Why we need more than a TSH test to understand your thyroid function

11 Jun 2020

Did you know that June is Thyroid Awareness month in Canada? Thyroid health is so important to how your body works but as many as 50% of people with a thyroid disease will go undiagnosed. Getting tested is the first step and to really see how your thyroid is working, it’s important to look at more than thyroid stimulating hormone (TSH).  Im going to share with you why we need more than a TSH test to understand your thyroid function.

Quick points you need to know about your thyroid: 

• The thyroid is a butterfly-shaped gland found in the lower front of the neck 
• The thyroid is responsible for production and release of thyroid hormones – T3 and T4 – which are released into circulation and carried to every tissue in the body
• The thyroid produces more or less of these hormones in response to signals from thyroid stimulating hormone (TSH)
• Thyroid hormones help to keep the brain, heart and muscles working their best, regulate our temperature to keep us warm and control metabolism and use of energy in the body

How a healthy thyroid works: 

In response to thyrotropin-releasing hormone, TSH is released from the anterior pituitary gland, found in the brain. It’s release and increasing levels tell the thyroid to increase production of thyroid hormones. T4 is released from the thyroid and is converted into T3, mostly by the liver. When the levels of T3 and T4 are optimized, they turn off the switch in the brain and TSH release is slowed down. 

When we look at blood testing for thyroid function, TSH levels tell us how strong a signal is coming from the brain to the thyroid. It’s a good test to use as an early warning sign. If it’s high or high normal, this suggests the thyroid isn’t making enough thyroid hormone. The downside of only testing TSH is that it doesn’t tell us why.

Naturopathic doctors like to see free T3, free T4, reverse T3 and thyroid antibody levels to help us understand the root of the problem. 

• Total T4 measures the bound and free hormone. Looking at free T4 allows your naturopathic doctor to assess how much T4 is in circulation, unbound, and able to affect the body tissues. 
• Often T3 testing is used by endocrinologists to assess hyperthyroidism. Your naturopathic doctor may want to see this test to determine how well your medication is working or to determine if an under functioning thyroid is the reflection of inefficient conversion of T4 to T3. In these cases, medication may not be necessary. Your naturopathic doctor may recommend vitamins and minerals that facilitate conversion and support liver function could help you feel much better! 
• Naturopathic doctors also like to test reverse T3. This product of hormone conversion pathways is inactive and can be high in people who are under a lot of stress. In some people with high stress, T4 conversion to reverse T3 is favoured ahead of active T3 resulting in low or low normal T3. In these cases, TSH could actually be testing as normal. Addressing the underlying stress and supporting adrenal function can help you feel much better! 
• Some people with low thyroid function are actually suffering from an autoimmune disease. For naturopathic doctors, this significantly changes how we would treat your case. Your naturopathic doctor may recommend including thyroid antibodies to fully assess your thyroid. If levels are high, you may have Hashimoto’s thyroiditis – an autoimmune form of hypothyroidism. These people require additional treatment on top of their standard thyroid medication to really feel better.  

Conclusion

So although TSH is a great way to take a quick look at thyroid function, it doesn’t tell us much. Looking at the thyroid hormones and antibodies alongside TSH gives your naturopathic doctor a much clearer picture of what is going on with your health and helps to determine the best plan for treatment. Now you know why we need more than a TSH test to understand your thyroid function.

If you’re interested in checking how your thyroid is working, book a virtual initial consultation with Dr. Alaina Gair, ND

By Dr. Alaina Gair, ND