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Friday, April 8, 2011

Thyroid Hormones

I thought I might take some time to try and explain the Thyroid gland, how it works and why I will need to be on medication for the rest of my life. 

The thyroid gland is a small butterfly shaped gland that lives at the base of the neck.  It produces thyroid hormones which are necessary to run our bodies by maintaining metabolism.  That is they make sure that organs are not running too fast, or too slow.  If you have too much thyroid hormone your body will overwork and this can be dangerous, especially to your heart. If your thyroid levels are too low, you feel run down. Very severe instances of low thyroid hormones can result in severe swelling of the tissues and coma. This is called "myxedema coma" and can be fatal. Therefore, it is very important that your body has the right amount of thyroid hormone. Your Thyroid gland produces two hormones T4 and T3.   However, your organs can't use the T4 hormone and so your body needs to change T4 to the active hormone T3. The half life of the thyroid hormone (T4) that your body produces is about 7 days. What this means is that every 7 days the amount of hormone will drop to half of it's previous level. So, if I started with 100% T4 before surgery, it would have been 50% last week and 25% today. The half life of the T3 is even shorter and so at this point I likely don't have any of my own T3 hormone. Without medication, my body will run out of thyroid hormone. That is why I was given the Cytomel. Cytomel is a T3 supplement which has a shorter half life. If I need to have RAI (Radioactive Iodine) which is the treatment fro thyroid cancer, I will need to be hypothyroid. Because the half life or T3 is shorter it would take less time for this to occur and the RAI could be done sooner. Also, T3 is the active thyroid hormone. T4 needs to be converted to T3 in the body to be effective. Therefore Cytomel will have effects sooner and so this may have played a role in the rapid weight loss I experienced the first week. Since I have not had any blood tests to determine the levels of my thyroid hormones it could be possible that my T3 was to high, thus increasing my metabolism and thereby decreasing my weight.

Side effects of Cytomel are related to allergic reactions or over dosage symptoms which are the symptoms of hyperthyroidism (too much thyroid hormone).  These can include:


fast or irregular heartbeat (palpitations)
feeling faint
mood swings
muscle weakness
extreme restlessness
light irregular menstrual cycles
heat intolerance
weight loss

In severe instances over dosage or severe hyperthyroidism can result in heart failure. 


  1. My thyroid is low. I have seen that some people who are using synthetic medicines suffer from depression/fatigue. But in my own belief, natural thyroid is much better compared to synthetic. I have been using it for many years now and there are no side effects.

  2. Thanks Gwen,
    I have been on synthetic thryoid medications for only 3 months now but I actually feel better than I have in a long time. My mood is more stable and I have more energy.