Thyroid Hormone Testing Dr. Kimberley O'Brien

Always Tired? Here’s Why You Should Consider Comprehensive Thyroid Hormone Testing

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Do you experience symptoms of hypothyroidism, including fatigue, water retention, depression, or constipation, yet upon thyroid hormone testing you’ve been told that your thyroid function is normal?

There’s a right and a wrong way to go about thyroid hormone testing, and in this article I’ll be sharing how I approach thyroid health as a naturopathic doctor. Early-stage cases of hypothyroidism are often missed through conventional thyroid hormone testing. This can lead to confusion and frustration when you feel certain that your thyroid is underperforming based upon the symptoms you’re experiencing!

What Are The Symptoms of Hypothyroidism?

Your thyroid is a small, yet critically important gland that sits at the front of your neck and regulates the speed of your metabolism. Thyroid hormones have the important role of providing energy to nearly every organ in your body. Your thyroid hormones also affect the production of your sex and stress hormones, control the speed of your heart rate, affect how easy (or difficult) it is for you to maintain a healthy weight, and influence your digestive function. Without adequate production of thyroid hormones, your bodily processes slow down, and fatigue is one of the primary symptoms you will likely experience.

A list of the most common symptoms you may experience with hypothyroidism include:

  • Fatigue
  • Weight-gain
  • Water retention
  • Bloating
  • Constipation
  • Feeling cold
  • Dry skin 
  • Hair loss
  • Depression
  • Poor memory
  • Joint or muscle pain and weakness
weight gain thyroid hormone testing

What Causes Hypothyroidism?

The most common cause of hypothyroidism is due to Hashimoto’s thyroiditis, which is an autoimmune reaction directed against the cells in your thyroid gland that produce thyroid hormones. This damages your thyroid and impairs its ability to produce adequate levels of thyroid hormones. I’ll discuss Hashimoto’s in more detail in the next section of this article on thyroid hormone testing.  

Other causes of hypothyroidism can be deficiencies of vitamins and minerals like zinc, selenium and iodine that are required for thyroid hormone production. It’s also possible for certain toxic elements, like cadmium or bromine to accumulate in your thyroid gland and block thyroid hormone production. Levels of other hormones, including estrogen and stress hormones like cortisol, will affect your body’s thyroid set-point if they are too high or low. Therefore, it’s very helpful to have a comprehensive picture of your hormone status to most effectively optimize your thyroid hormones. 

Hypothyroidism affects women more frequently than men, and the incidence of hypothyroidism  becomes more common with advancing age. As a naturopathic doctor, I routinely screen my patients for hypothyroidism, especially if they are also experiencing symptoms like weight gain or constipation in addition to their fatigue.  In addition to thyroid hormone testing, which I’ll discuss further in the next section, I often also assess sex and stress hormones for my patients via detailed urinary-based hormone assessments.

thyroid hormone testing naturopathic doctor

What You Need to Know About Thyroid Hormone Testing

If you suspect that hypothyroidism may be at the root cause of your fatigue, it’s very important that you work with a doctor who is well-versed in proper thyroid hormone testing. Unfortunately, early-stage hypothyroidism is often missed through conventional medical testing. This is because the testing is not performed in a way that will detect subtle shifts in hormone levels. 

Thyroid stimulating hormone (TSH) is a hormone that the pituitary gland in your brain produces to instruct your thyroid gland to produce thyroxine (T4). From there, your body must convert the T4 it has produced into the most active thyroid hormone, triiodothyronine (T3). If all is functioning correctly, T3 should provide feedback to the pituitary gland that there is enough thyroid hormone and reduce your TSH levels. If your T3 levels are too low, that should signal to your pituitary gland to increase TSH production since more thyroid hormone is required.   Although I know this sounds complicated, what you need to understand is that a LOWER value for TSH means that you have a HIGHER level of thyroid function (which is what we want!). 

Optimal thyroid function is generally associated with a TSH value of approximately 1 to 2 pmol/L, but unfortunately the conventional “normal” reference range far too wide (ranging from approximately 0.5 to 5.0 pmol/L through most labs). Upon thyroid hormone testing, you will likely be told your thyroid function is completely normal until your TSH levels are above 5 pmol/L.  This means that even if your TSH level is up to 4 pmol/L, which is twice as high as the upper end of the optimal range,  your results still fall within conventional “normal” range. Know that if your test results have been reported within “normal” range, you may NOT necessarily be within the optimal range.  Additionally, more extensive testing is always required to identify if you have enough active thyroid hormones (T3 and T4).

TSH is generally all that’s tested through conventional medical screening, but unfortunately there are issues that can occur along the chain of thyroid hormone production that aren’t always fully reflected in your TSH levels. For example, there are rare cases of “central hypothyroidism”, which result when your pituitary gland does not release enough TSH despite abnormally low T3 and T4 levels. Additionally, I diagnose many cases of sub-optimal thyroid function in my practice, which is when T3 and T4 are below their ideal range despite a normal TSH.  If your T4 and T3 levels are not tested as well then we simply do not have the full picture in regards to your thyroid health.


Thyroid Hormone Testing for Hashimoto’s Thyroiditis

As mentioned earlier in this article, Hashimoto’s thyroiditis is the most common cause of hypothyroidism in North America.  For those with Hashimoto’s, thyroid antibodies are produced as part of an immune reaction that your body is directing against your thyroid gland.  These antibodies, called thyroid peroxidase antibodies (TPO), can often be detected in your bloodstream long before there is enough damage to your thyroid gland to produce obvious changes in your thyroid hormone levels. This provides us with an important opportunity to assess and address the underlying cause of this immune over-reactivity BEFORE you have long-term damage to your thyroid requiring hormone replacement. Therefore, I almost always test TPO antibody levels as part of my screening protocol for potential thyroid issues.

Hypothyroidism and Thyroid Hormone Testing

How is Hypothyroidism Treated?

Hypothyroidism is treated by replacing your thyroid hormones with thyroxine (Synthroid) or with a combined prescription that provides both thyroxine (T4) and triiodothyronine (T3) replacement.  The good news is that if hypothyroidism is caught early, which it often is when more extensive thyroid hormone testing is completed, then it’s likely we can avoid the progression of thyroid damage and the need for thyroid hormone replacement.  

Treatment should always be geared specifically to the cause of your hypothyroidism, whether that be calming an autoimmune reaction, boosting nutrients that are required for optimal thyroid function, or clearing toxic elements from your body that are impeding thyroid health.  Working with a health practitioner who is well trained in the natural treatment of hypothyroidism, such as a naturopathic doctor, will help you to benefit from a clear and targeted treatment plan.

Foods for thyroid health

What Other Imbalances May Be Dragging Down Your Energy?

Often there may be more than one underlying cause of your fatigue and other symptoms, and it’s important to do a thorough health assessment to ensure that other imbalances aren’t missed. For example, there are many nutrient deficiencies that can lead to fatigue without affecting thyroid hormone levels (ex: vitamin B12).  Additionally, if you have been diagnosed with Hashimoto’s, we might discover that food sensitivities are one of the elements causing you to experience elevated immune reactivity. It’s also important to note that the symptoms of food sensitivities may include fatigue, brain fog, joint pain, bloating and constipation, which closely mimic the symptoms of hypothyroidism.

I encourage you to download my free eBook, Fatigued to Fabulous, which includes a quiz to help you determine if your symptoms may be caused by hypothyroidism or if something else could be at play for you. What has your experience been with thyroid hormone testing?  Let us know in the comments below!

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Always Tired? Here's what you need to know about thyroid hormone testing

About the Author

Dr. Kimberley O'Brien


Dr. Kimberley O'Brien is a Naturopathic Doctor in  Nelson, BC with expertise in the treatment of digestive disorders, fatigue and hormone imbalances.  She is the founder of Healthy Life Redesign and creator of the Elimination Diet Meal Plan and the Real Food Recharge online programs.  Her mission is to help you own your health and live a life you love!

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