In the previous thyroid article, we discussed about the importance of a healthy thyroid, how it works, and what symptoms you might experience if your thyroid is not working properly or if your thyroid hormones are out of balance.
Your thyroid is like the engine in your car. It dictates how fast or slow you are moving. In your body, it also determines how many calories you are burning and how fast your body produces energy. The following symptoms were found to be associated with low thyroid function:
- Dry skin, fatigue, cold sensitivity, constipation and muscle cramps [1]
- Increase in cholesterol, low-density lipoprotein (LDL) cholesterol, and triglycerides. [2]
- Subclinical Hypothyroidism was found to be associated with ischemic heart disease in people of 65 years and younger. [3]
- Lower sexual function, Depression. [4]
- Slow bowel movement or constipation. [5]
- Dysfunctional sugar metabolism as was noticed by higher HbA1C. [6]
- Cold hypersensitivity in the hands and feet (CHHF) [7]
- Hair loss [8]
- Chronic fatigue [9]
- Headaches [10] *clinical observational note, occasionally reported in the morning
- Weight gain (especially associated with levels of free T3 and free T4 levels) [11]
Why are most people with low thyroid function undiagnosed?
The reason for that is simple. When complaining of thyroid symptoms, such as fatigue, weight gain, constipation, or even the presence of high cholesterol in your labs, most doctors will only test for the thyroid-stimulating hormone (TSH). This measures how much your anterior pituitary is trying to stimulate your thyroid to work. There is an assumption within the medical community that measuring how much the thyroid is stimulated is enough to determine whether it is working. Unfortunately, that is not always the case.
A study published in the Journal of Nutritional & Environmental Medicine showed that, in many cases, thyroid symptoms did not correlate with levels of TSH. (12) This means that if you went to your doctor and complained of fatigue, constipation, cold hands or feet, or weight gain, measuring your TSH levels is just the “tip of the iceberg”. It won’t show the whole picture. Many patients are misdiagnosed and do not know it. Their doctors look at their labs and send them home while they still suffer from symptoms of low thyroid function.
Why is it important to measure T3 and T4 and not just TSH?
The thyroid makes two hormones: T3 and T4. Measuring the hormones that the thyroid produces will show us how much your thyroid gland is working. Unfortunately, many doctors test a small number of these hormones, such as just TSH.
Take the hormone T3 for example. A study published at the Department of Medicine of University of California, found that normal levels of TSH may not be correlating with normal levels of T3. [12] This means that measuring your TSH hormones, without measuring T3, will not give us enough information about how much thyroid hormone T3 you have in your blood. You might have normal levels of TSH, but low levels of T3. Remember that T4 is converted to T3, the most active hormone that stimulates your cells and metabolism. If your levels of TSH and T4 are normal, but the T3 is low, all the cells in your body won’t be stimulated enough to work properly.
If your TSH, T3, and T4 levels are normal, could you still have symptoms of low hypothyroidism?
The short answer is, yes. Measuring your TSH, T3, and T4 is a good starting point, however, to get a complete picture of the thyroid-related function, we must also measure reverse T3 (rT3) and thyroid antibodies. Reverse T3 is a biologically inactive form of the active hormone T3. In other words, it does not activate the cells as T3 hormone does. It simply ‘floats’ in your blood without influencing your metabolism and energy production. Another study found that rT3 is not just an inactive metabolite, but a powerful inhibitor of the conversion of T4 to T3. It is so powerful that it is estimated to be 100 times stronger than propylthiouracil, a medication used to decrease thyroid function. [13]
What causes the conversion of T4 to Reverse T3?
Factors or triggers that increase conversion of T4 to RT3 are chronic stress, trauma, low-calorie diet, inflammation (cytokines, etc.), toxins, infections, liver/kidney dysfunction, and certain medications. [12] That is why, in some cases, it is important to measure T4, T3, and reverse T3.
While most doctors do not look at these factors, a well-trained Functional Medicine doctor will be able to identify these triggers, offer the appropriate lab testing, and address these triggers. The biggest challenge in a world of a ‘pill for every ill’ is that if we ignore these triggers, they might lead to other health problems, such as inflammation, oxidative stress, and cellular damage. Eventually, many of these patients might develop more symptoms or chronic diseases.
Can thyroid antibodies destroy your thyroid?
Another important factor to consider is thyroid antibodies, Anti-thyroid peroxidase (anti-TPO), and Thyroglobulin Antibodies (TgAb), which impair the proper function of the thyroid. The presence of these antibodies might indicate systemic inflammation and that your thyroid is being attacked. [12, 14] It is important to measure these antibodies since there your immune system (antibodies) might be ‘attacking’ your thyroid and you might not know it.
Impaired Sensitivity to Thyroid Hormones
The last thing to mention about the connection between your thyroid hormones and the rest of your body is T3 receptor issues. In certain chronic conditions, your body might not respond to the thyroid hormones (such as T3). In this case, even proper and healthy levels of TSH, T4, and T3 will not be enough, since your cells will not respond to them. An example for this condition is called impaired sensitivity to thyroid hormone, which was previously referred to as reduced sensitivity to thyroid hormone or Mild Acquired Thyroid Hormone Resistance. This condition describes a reduction in the effectiveness of thyroid hormone on the cells and includes defects in the action or metabolism of the thyroid hormone, leading to clinical symptoms.
Impaired sensitivity to thyroid hormone (ISTH) might lead to several symptoms and chronic conditions. For example, ISTH was found to be associated with higher levels of HbA1c and a higher risk of diabetes-related deaths and metabolic syndrome. [15]
From my experience, high levels of T3 together with symptoms of low thyroid function (fatigue, excess weight, etc.), might indicate that your cells do not respond to these hormones, which could be due to high reverse T3, a state of chronic (and possibly subclinical) inflammation, or nutritional deficiencies that prevent cells and enzymes from functioning properly.
Addressing symptoms of low thyroid and hormonal imbalances
To find out what might be causing your symptoms and is ‘holding your body’ from getting healthier, you must start with a comprehensive review of your symptoms, thyroid, related hormones, diet, and lifestyle. A well-trained Functional medicine provider would be able to order the right tests and provide you with a complete picture of your thyroid function, related hormones, and your body’s reaction to these hormones. Most doctors won’t order these tests, so find a Functional medicine provider that will properly evaluate the function of your thyroid and will look for thyroid symptoms. If you are not testing, you’re guessing.
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