The American Thyroid Association has published a document on thyroid hormone treatment thyroid.org/thyroid-hormone... . They have also invited feedback on this and other documents atassoc.informz.net/z/cjUuc... . I suggest we add our comments as it is a pretty dreadful document. I have submitted the following: -
This document is dreadful, full of inaccuracies. Some examples: -
1. 'Thyroid hormone used in two situations' Ignores central hypothyroidism, subnormal TSH secretion, down-regulated axis, RTH, endocrine disruption and no doubt other possibilities.
2. 'dose adjusted to keep thyroid levels normal' TSH, fT3, fT4 are dependent variables, it may be necessary to have levels that are not 'normal' to achieve clinical euthyroidism as in RTH, central hypothyroidism, TSH with low bioactivity. Have the authors ever studied thyroidology?
3. Desiccated prescription NDT, e.g. Armour. Claims that 'The amounts of both T4 and T3 can vary in every batch of desiccated thyroid' are false, prescription NDT has well controlled hormone content. In recent years there have been many levothyroxine recalls, especially in the USA. Levothyroxine has a very poor absorption profile which can lead to erratic dosing.
4. 'contain hormones and proteins that do not exist in the body outside of the thyroid gland' Same applies to a steak and kidney pie or a natural skinned sausage. What's your point?
5. 'Animal thyroid extract should not be used in pregnancy, as the T3 portion does not reach the developing baby' This is disgraceful scaremongering. I'm aware of studies that appear to show T3 does not cross the placenta. However, NDT has been in use for over a century with no apparent harmful effect on pregnancy or development of the baby. Many women on L-T3 monotherapy have successful pregnancies, in some cases they only achieve pregnancy after switching to L-T3. This enigma should be addressed, in the meantime it is highly unethical to give the impression that NDT, L-T3 / L-T4 combination therapy or L-T3 monotherapy is harmful to pregnancy.
6. The claims that L-T3 has a 'very short life span', 'levels decrease very rapidly in the bloodstream', 'has to be taken several times each day' are an exaggeration with the intention to mislead and scare patients - highly unethical. The half life of 24 hours is not a problem if two or three doses are taken daily, indeed Celi showed that with thrice daily dosing there was no difference between liothyronine monotherapy and levothyroxine academic.oup.com/jcem/artic... . We should note that your authors presumably have no qualms about prescribing carbimazole (half-life 4 to 6 hours). Perhaps someone should explain the difference between pharmacokinetics and pharmacodynamics to your advisors.
7. Combination L-T3 / L-T4 therapy. It is stated combination therapy is 'given' once a day. Most patients I know split their doses. Where is the evidence for once daily dosing?
8. Combination L-T3 / L-T4 therapy. 'patients that do not feel completely normal on T4 alone', this is abusive. Your authors will be well aware that many of these patients have their lives destroyed by inadequate thyroid hormone therapy.
9. Combination L-T3 / L-T4 therapy. 'doses that are closer to the normal human thyroid balance'. Why? See point 1. There are many cases where restoring 'normal' serum hormone levels will be inadequate. Many such patients are excluded from studies because their TFTs are 'normal'.
10. 'Some people with normal thyroid blood tests have symptoms that are similar to symptoms of hypothyroidism'. Such patients probably have impaired deiodinase, particularly D2 which regulates local T3 levels. Restoring normal blood T3 will not restore low intracellular T3 due to impaired D2 activity. Indeed prescribing L-T4 will lower TSH further reducing D2 activity. In cases of RTH or endocrine disruption normal blood hormone levels will be inadequate.
I suggest you delete this document. I am willing to help you produce an evidence based document if you wish.
GP HAS QUOTED THE FOLLOWING NOT TO GIVE ME T3
