One of the most common complaints I have seen in practice over the years is “My doctor says my blood tests look normal, how come I cannot lose weight?”
The most common blood test ordered to address thyroid function is known as TSH (Thyroid Stimulating Hormone). However, this hormone is only one marker of thyroid function and sometimes misses the whole picture of how healthy the thyroid truly is. It is best to not only understand how the brain is responding to thyroid function, but also to understand how much hormones the thyroid gland is producing and, if the thyroid is under attack from antibodies.
If you are looking to reach a healthy weight and you have either already been diagnosed with hypothyroidism, or you believe you may have hypothyroidism despite your TSH test being “normal”, I strongly encourage you to have more blood tests.
Statistically, hypothyroid is an under diagnosed condition. In fact, it is estimated that in the US only ½ of Americans that have hypothyroidism know it!!
Testing the Thyroid
Thyroid tests should be easy to obtain from your primary Medical Doctor, Naturopathic Doctor or Functional Medicine Doctor. However thyroid tests do take some skill to interpret and some Doctors may be reluctant to order more than a TSH test, especially if you are working within a public health care system. If this is the case, consider getting a second option by a doctor that is familiar with thyroid health and testing.
Thyroid Test #1: TSH (Thyroid Stimulating Hormone)
This hormone is produced by the pituitary gland (a small gland in your brain). TSH communicates with the thyroid to tell it to produce more thyroid hormones such as T3 and T4. When thyroid function is optimal in the body, TSH is in a normal healthy range and so is T3 and T4. However, when the T3 and T4 hormones are LOW, TSH starts to INCREASE, telling the thyroid gland to pick up the pace and produce more T4 and T4.
The “healthy TSH range” has become a somewhat controversial topic in medicine. Most Canadian labs consider the upper range of TSH to be 4-5mIU/L. But, many experts, including many conventional endocrinologists, consider the upper limit of TSH should be no higher than 2.5-3mIU/L. This is based on the data collected on Americans without any hypothyroid symptoms. When these healthy individuals have a TSH test done, the upper range of TSH is not over 3mIU/L. If your TSH is consistently close to 3mIU/L and you also have symptoms of hypothyroidism, more testing may be very helpful!
Thyroid Tests #2: Free T4 (thyroxine)
As mentioned above, T3 and T4 are hormones produced by your thyroid gland. T4, known as the INACTIVE thyroid hormone, is produced in much higher amounts by your thyroid gland, and then is converted into the ACTIVE T3 in the periphery (by the liver, kidneys, digestive tract). Testing Free T4 provides an indication of how much hormone is being produced directly from the thyroid.
Thyroid Test #3: Free T3 (Triiodothyronine)
T3 is the ACITIVE form of thyroid hormone and is necessary for metabolic function. By testing for Free T3, it can provide an indication of how well you are converting the T4 thyroid hormone into its active form. If you are currently on thyroid medication (synthroid or levothyroxine), the body must convert the medication into T3. Some individuals have difficulty with this conversion. However, if your T3 is low, there are supplements and dietary changes that can be helpful to increase conversion!
Thyroid Tests #4 TPO (Thyroid Antibodies)
Autoimmune hypothyroidism is the most common cause of hypothyroid. As with any other health condition, to achieve optimal health we must look at the underlying cause of the problem. If a patient has hypothyroidism, but does not address the autoimmunity (if present), the problem will not be addressed at the root cause. Thyroid antibodies can also be measured every 6-12 months to gauge how thyroid treatment is progressing. Testing TPO can not only reveal if there is underlying autoimmunity, it can also provide early detection of hypothyroidism. TPO antibodies may be elevated in the body for up to 5 years before TSH levels change. This is very important because if you address autoimmunity before TSH becomes too high, the thyroid may be brought back into balance.
If you have an inkling that your thyroid health is sub-optimal and your doc is not open or familiar with thyroid testing, consider switching doctors or having a second opinion.
Yours in Health,
Dr. Emily