To understand the purpose of thyroid replacement therapy, you need to understand the how thyroid hormones interact with each other. T3 and T4 are the hormones that are necessary to sustain life. If either of them are out of balance it can wreak havoc on health.
The thyroid gland is controlled by the pituitary gland, a small peanut-sized gland at the base of the brain. When the amount of thyroid hormones (T3 and T4) dip below optimal amounts in the body, the pituitary gland releases Thyroid Stimulation Hormone (TSH) which tells the thyroid gland to make more hormones.
The function of the thyroid gland is to take iodine, found in many foods, and convert it into thyroid hormone T4. The cells in the thyroid gland absorb iodine and combine it with the amino acid tyrosine to make T4. This T4 is then released into the bloodstream. T4 is not the active thyroid hormone; it has to be converted into T3 in your body in order to activate your metabolism. This conversion mostly occurs in your liver, kidneys, and muscles. However, this conversion doesn’t always occur properly in some people for various other reasons. It could be that your liver is overloaded or your kidneys aren’t functioning as well as they should, but there are other hormonal imbalances that can also cause this to occur. If your T3 production is low or, if you are having issues with converting T4 to T3, you may feel tired, depressed, constipated, and experience other symptoms such as feeling puffy, gaining weight, have dry skin, and experience hair loss. If due to such issues or other reasons for insufficient T3 production, you may feel tired, depressed or puffy, have dry skin, and experience unwanted hair loss.
Every cell in your body depends upon thyroid hormones for regulation of their metabolism. A healthy thyroid gland generally produces about 80% T4 and about 20% T3, however, T3 possesses about four times the hormone “strength” as T4. T3 and T4 control your body’s metabolism. If you don’t have enough hormone, then your metabolism slows down. Your metabolic rate dictates how quickly you process food, how fast your heart beats, how much heat your body generates and even how quickly you can think. In short, T3 and T4 are in charge of how your body uses energy.
Despite T3 being the stronger of the two, taking synthetic T4 hormone is considered the “standard” treatment for hypothyroidism, with the reasoning being that the body will take T4 and turn it into T3. However this is not always the case and it can often occur that when T4 is taken very little T3 is produced. This is why some people have little to no effect from taking common thyroid treatments as they are a synthetic T4 and their body is not effectively transforming it into T3.
In some cases the body actually converts T4 into Reverse T3. This increase in Reverse T3 typically intensifies the symptoms of low thyroid hormone disorder; most noticeably an increase in fatigue and weight gain.
The mainstream medical community usually tests your TSH (Thyroid Stimulating Hormone) level and possibly your T4. If either of those indicate that your thyroid is underperforming, you are generally prescribed a T4 medication such as Synthroid or Levothyroxine. The medical community has long been aware that testing only these two measures is an inadequate measure of thyroid function, yet this practice still commonly occurs. If someone has a T4 to T3 conversion problem, this will not show up on these tests. Additionally, if the cause of Hypothyroidism is actually Hashimoto’s Disease, this will not show up either since the testing isn’t looking at antibodies.
At Renewed Vitality, we always run a full thyroid panel which includes testing for TSH, T3, T4, Reverse T3, and for thyroid antibodies which would indicate a Hashimoto’s diagnosis. By doing this, we are able to treat the root cause of your thyroid problem, and provide you with relief of symptoms and better health.