Gettysburg Medical News
The Clinical View
by P.E. Hoffsten, M.D.
12 March 2008

WHAT IS HASHIMOTO’S THYROIDITIS?

            Wow, what a crazy name!  The name comes from Dr. Hashimoto who published a paper in 1912 in the German medical literature about a patient that had a nodular hardening of her thyroid gland.  Over the years, a characterization of what caused this abnormality of the thyroid gland was studied much further and now we know a lot more about than we did 96 years ago in 1912. 

            The question came up from a lady who had been to Mayo Clinic and been told that she had Hashimoto’s thyroiditis.  I had never seen her before but she said that she had more questions than answers after she had been to Mayo Clinic.  She wanted some explanations.  Her story was one of having had a “check-up” in which thyroid tests were done.  It turned out that two of the thyroid tests were abnormal.  Specifically her “TSH” (thyroid stimulating hormone) was very high and her thyroid hormone level was very low.  Thyroid stimulating hormone is made in the pituitary gland in the brain and it goes to the thyroid gland and tells to get to work.  Whenever the thyroid level in the body drops too low, the brain figures that out and tells the pituitary gland to make thyroid stimulating hormone to tell the thyroid gland to get to work.  Basically what had happened in this lady was the thyroid gland just wasn’t working well enough and the pituitary gland was yelling at it to work harder.  The question was raised as to why this situation existed.  The local physician that had been caring for this lady tried to explain to her but she wasn’t satisfied so she went to Mayo Clinic and now she still wasn’t satisfied.   So we sat down to figure out what she wanted to know. 

            First, she wanted to know what was Hashimoto’s thyroiditis which is what Mayo Clinic told her she had.  I explained that this was in a disease in which she had become allergic to her own thyroid gland and that the immune system in her body was attacking her thyroid gland.  She said that she had been told this but just couldn’t believe it.  I promised her it was the truth. She then wanted to know why her body was doing that and I had to explain that we didn’t have a clue.  It is a condition called autoimmunity in which for some reason the person’s immune system decides that a given part of the body doesn’t belong anymore and the immune system decides to reject it.  This is very much like what the immune system would do in rejecting a foreign piece of skin or a foreign kidney or a foreign heart that is transplanted unless immunosuppressant drugs are used. 

            She then wanted to know what could be done to stop her immune system from attacking her own thyroid gland.  I explained that immunosuppressant drugs such that are used for transplant patients might be tried if she was hurting or there were life threatening situations developing.  But then I explained to her that that really wasn’t the case.  Her thyroid gland did not hurt her and simply by replacing thyroid hormones, her thyroid status could be rendered normal again.  So immunosuppressant therapy was not a necessary or useful step and would cause more complications than benefit.  Mayo Clinic had told her that she should take 125 micrograms a day of levothyroxine which is the normal hormone that the thyroid makes.  It had already been found that that was the right dose that would make her TSH levels come back to normal and let her brain quit telling her pituitary gland to tell the thyroid to work harder.  With just 125 micrograms a day of thyroid hormone, her body’s needs were met. 

            Her next question got complicated.  It turns out that the thyroid hormone is changed into a different product called T3 (triiodothyronine) by the cells in the body.  This T3 is probably the main driver regulating our metabolism.  She had been told by her sister that she needed to replace her T3 in addition to the Levothyroxine that she was already taking.  Her sister said her doctor gave her Cytomel (synthetic T3) and that the patient really should be taking the same thing.  The patient wondered why Mayo Clinic hadn’t prescribed Cytomel for her. 

            This is a classic example of how anybody that is more than 60 miles away knows more than any doctor in the town that you live in.  If your sister in New York tells you something, it carries much more authority than the Mayo Clinic or the doctor in your local community. 

            I explained that 80% of the hormone released by the thyroid gland is the native levothyroxine (T4).  But 20% of thyroid released hormone is triiodothyronine or T3.  Even if the person makes no T3 from their own thyroid gland, the peripheral tissues of the body will change T4 into T3 and the body will have plenty of T3. The need for Cytomel (synthetic T3) supplementation is vanishingly rare except for some esoteric hereditary diseases.  There is no need for a hypothyroid individual to be supplemented with T3 unless you have stock in the company that sells Cytomel. 

            Lastly, the lady asked if there were other things that she needed to worry about.  In my mind, I thought she already worried enough and didn’t need anything more.  But there was one additional consideration.  As fate would have, individuals who develop autoimmunity to their thyroid gland often develop autoimmunity to other tissues in their body.  For people with Hashimoto’s thyroiditis, there is an increased incidence of a disease called pernicious anemia.  This is a disease in which patients become allergic to the acid producing cells in their stomach and they develop Vitamin B-12 deficiency.  Thus, I told her it was important in the long run to keep track of the B-12 level which we checked and was normal.  Because the autoimmunity to her thyroid gland may be progressive, it was important to check her hormone levels every 6 months to be sure that she stayed in balance. 

            You don’t really need to go to Mayo Clinic to understand Hashimoto’s thyroiditis.  The healthcare providers at your local clinics are very competent to draw thyroid levels and adjust the hormone supplements as needed.  Hashimoto’s thyroiditis is only one cause of a low thyroid condition but basically they are all treated the same.  Simply replace the amount of hormone the person needs and live happily ever after.  And you don’t need to supplement T3 (Cytomel).

This and other columns available at www.macpierre.com.