Breakthrough Discovery: Need For t3 Could Be Genetic


Do you wonder if you need t3 (Cytomel, triiodothyronine, liothyronine) added to your thyroid hormone treatment to feel normal again? The answer could be in your genes.

Recent discoveries reviewed by Antonio C. Bianco, M.D., Ph.D. at the recent American Thyroid Association meeting, reveal how genetic differences influence the effectiveness of thyroid hormone replacement. Dr. Bianco’s lecture focused on studies pinpointing inborn differences in the way people metabolism thyroid hormone to explain why t3 treatment of hypothyroidism is probably required by some to restore normal functioning of their brain, muscle and heart.

The most frustrating problem for people with hypothyroidism is being unable to convince their doctor that treatment with Synthroid, Levoxyl or similar pure t4 product, isn’t working. Continued symptoms of fatigue, weakness, inability to concentrate or think clearly, and inability to lose weight despite really trying, result in tension between the doctor and the “complainer”. When assessing the adequacy of thyroid hormone replacement therapy most doctors rely on the blood tests known as the Thyroid Function Panel. Typically this includes a measurement of t4, t3, t3RU, and TSH. Some panels may also include free t4 or free t3 measurements. If the hormone levels on these tests are “within normal limits” the doctor will often insist that the treatment is a success but it is the patient who fails to recognize this. A minority of endocrinologists know many of these “failures” can be turned into success by the addition of t3, the less utilized but much more powerful form of thyroid hormone.

Most of the biological effects of thyroid hormone in the body are due to the action of t3. The most common forms of thyroid hormone replacement however, involve giving t4 in the form of Synthroid, Levoxyl, levothyroxine etc. The t3 required by our tissues is produced by specific enzymes which convert t4 to t3 in the cells of the liver, kidney, brain, muscle, heart etc. These converting enzymes are known as deiodinases and under normal conditions they are responsible for about 80% of the body’s t3. The process
by which t3 is produced from t4 is known as peripheral conversion.

It has long been the contention of the leaders in thyroid disorders that based on their arithmetic, t4 replacement is sufficient to provide all the t3 the body needs via peripheral conversion and giving t3 supplementation doesn’t make good medical sense. Now, based on the new information provided by researchers like Dr. Bianco, the “arithmetic guys” will, in my opinion, need to revise their thinking finally allowing the way for acceptance of t3 replacement approaches.

I will continue the explanation of the new breakthrough in genetic control of thyroid hormone replacement treatment in Part 2 of this post.

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  • Ruth Watchorn RN CCM LNCC CLCP MSCC

    Thank you!!! Dr. Pepper, endocrinologist, spoke of your findings on a support talk/chat last night. I am grateful to you for publishing this article. Perhaps, now the “rigid” endocrinology world will start once again treating patients properly and stop ignoring symptoms. It seems we have lost a great treatment method,(that being the addition of porcine dissicated thyroid) once used in the past, which has remained lost since the development of Synthroid and the “gold standard” TSH test, which unfortunately most endo’s reley on. T4 only meds do not work for some patients. It is amazing how pockets can be lined by big pharmaceutical companies and docs can lose their way. Patients have remained sick for years because of this rigid thinking. Thank you for your research, discoveries and exposing the lies. Ruth

  • Sally

    This explains a lot for me. I look forward to part 2.

  • Eric Pritchard

    I believe that there is a test that can be done, but I don’t know precisely what it is. As Dr. Ridgway noted before the FDA meeting on bioequivalncy of the various levothyroxine sodium preparations, the action is T3 in the nucleus, not T4 in the serum. So then the T3 must become, in some form, a waste product that is taken out of the blood. Then if there is not enough or too much of that waste product, then there is deficient or excessive metabolism — it would seem. Abnormal results would then demand further examination. And this would be the case with or without thyroid gland therapy.

    However, the endocrinologists insist that only the thyroid gland can be out of wack as they concentrate on the TSH results often to the exclusion of other results. From a systems test stand point this is just plain idiocy. The TSH is at least three operations away from the production of the symptoms and that does not even count the hormone clearance functions that exist for all of the hormones (which is why urine tests work). And that does not count the various enzymes that are required.

    There is a great advantage of simplifying. However, oversimplification can make things more difficult.

  • Phyllis J. Nagle

    This is so interesting. I am on 137 mg. Synthroid, and I cannot lose, or if I cheat on food, I do not gain. I am desparate about this. I want to lose 10 pounds, and the drs. do not say anything. They say, the test is normal. I would even take a diet pill if I could be guaranteed a good one. Please help me, if you can. Sincerely, Phyl Nagle

  • Phyllis J. Nagle

    What can I do?

  • Sally

    This explains a lot for me. I look forward to part 2.

  • Alsgal

    Hello,
    As I sit here and search the web for help with my Hashimoto’s Thyroiditis..I just want help in feeling good again!!! I have been battling extreme fatigue, mental fog, shortness of breath, heart palpitations & all the hypothyroidism symptoms..I have been on Synthroid since 2007 and started having all the symptoms above in 2009 was Dx with super ventricular tachycardia and put on Bystolic and did not get Dx with Hashimoto’s until Jan 2011..they feel the SVT was caused by the Hashimoto’s and I have since gotten off the bystolic do to it putting me into a deep depression & weight gain!! (60lbs)..I have seen 2 endocrinologists in the past 2 years with no help treating my symptoms!! I finally ask my PCP to change me to Armour thyroid and the first 2 weeks I began to feel normal again then I started going down hill again and I am back at feeling HORRIBLE!! Of course I look back at my labs and no T3 was ever run. My current TSH last week was .32 so my PCP cannot increase my dose of Armour and wants me to get TSH done again in 6weeks..Now I am looking for ANOTHER endocrinologist to go to..but want one who specializes in Hashimoto’s..I live in the DFW area in Tx if anyone knows of a GREAT Doctor…PLEASE let me know!! 53 y/o female at her wits end!!

    • Barb Fawcett

      hello, OH MY!! I have Hashimoto’s Thyroiditis and just turned 60 today. I was diagnosed when I was between my 3rd & 4th child I think I was about 33. I had this lump in my throat and a sore red throat for almost a year. I worked in the ER at a Hosp. but you know there is never any time for yourself! I went to an internist and he told me what it was. He did a t3, t4 & t7 and I think tsh which is standard testing. I went through the radiation pill etc. I was put on 3 grains of Armour then later on 4 grains. I felt pretty good for some time. This Dr. did not believe in taking the goiter out so he never did. After years of stress and moving to a place where no dr would give me armour, I had to take synthroid. I became very heavy when I was always thin, always exhausted, my hair did not grow hardly at all anymore and I was a shadow of my former self. I spent lots of time resting and had no energy. The opposite of what I had always been. We did move again years later and I just called dr.’s asking the nurses if they would perscribe Armour and I found one who would so I went to him and he did listen. However after a while I would periodically feel like I had the flu-weak, achy etc. i was referred to an endo and she said I tested at no thryoid hormore in my body at all. I felt like it too! My brother-in-law who is a pharmacist says that Armour can have a powerful batch in one and a weak batch in many others. My sister in southern Illinois said she was on synthroid (not hashimotos) (a disturbed student strangeled her and hurt her thyroid and it had to be removed) she said she was put on cytomel t3 also and she was feeling great. Her dr. said when she felt punkish they would up the t3 a bit to suit her body meanwhile taking her levels. Tomorrow I am going to go to my wi dr. and hope he has brains enough to give me t3 because I know my body doesn’t make much at all if at all. I don’t think alot is known about hashimoto’s. It is not like the other thyroid disorders it is different. fyi I was diagnosed prob. late with heart failure almost 10 years ago. I am also tired of ineffective doctors and wasting time and money. I don’t think we have any good doctors in our town that I know of so prob. Milwaukee at least.
      Good luck! Barb

  • Eric Pritchard

    Endocrinologists have a hard time with the symptoms of hypothyroidism in the same sort of way that New York City folks believing that there is anything worthwhile west of the Hudson River. However, there are very relevant functions to the thyroid hormone effectiveness that exist beyond the boundaries of the classical endocrine system. This potential was given initial credence by Drs. Kirk and Kvroning in 1947 when they published a note saying that not all patients’ symptoms were managed by thyroxine (T4). This was collaborated in 1954 by Dr. Means. Drs. Gross and Pitt-Rivers discovered triiodothyronine (T3) and found it far more active than T4, which is now called a pro-hormone. The concept of euthyroid (your thyroid is OK) hypometabolism (but you are dragging anyway) was demonstrated by Dr. Goldberg in 1960. Drs. Refetoff and Braverman, circa 1970, discovered the connections between the thyroid gland and symptom producing cells, namely the cellular reception of hormones and the conversion of T4 to T3 outside of the endocrine system, which produces 80% of the body’s requirement for the active hormone, T3.

    Another issue that is dismissed is the necessity of supporting chemistry to function properly. For example, every thyroid hormone replacement counter-indicates is use if the adrenals are insufficient.

    So there is far more going on than endocrinology is willing to promote. That is why there are 1.7 million patients suffering in spite of T4 therapy. That is why there are still more patients suffering from false negative diagnoses for the symptoms of hypothyroidism.