Why So Many Thyroid Patients Fail to Recover on Levothyroxine (T4)

This is a great new blog post from Dr Tania S. Smith of Thyroid Patients Canada.

The post clearly spells out the reason why so many thyroid patients who are taking Levothyroxine continue to feel unwell. Levothyroxine is the synthetic version of the T4 thyroid hormone (also known as Synthroid in the USA).

Levothyroxine simply does not provide the same amount of T3 that healthy people have. On Levothyroxine, the thyroid patient often has higher T4 and lower T3 levels than healthy people. T3 is the biologically active thyroid hormone, so being deficient in T3 compared to healthy people is a real issue.

The research paper that Dr Smith bases her blog post on was actually published in 2011. So, this information has been with endocrinologists and doctors for a long time! However, treatment practices did not change because of the research!

The article fits totally with what thyroid patients already know and what so many doctors and endocrinologists refuse to believe: Levothyroxine frequently leaves some thyroid patients with remaining symptoms.

To make things worse, in far too many cases FT3 is not the primary thyroid hormone test that is being used alongside the patient’s symptoms and signs to assess the efficacy of treatment.

Something really needs to change with thyroid treatment. The current approach is based on false assumptions. It is a failed treatment paradigm.

The article is well worth a read:

Best wishes,


Paul Robinson

Paul Robinson is a British author and thyroid patient advocate. The focus of his books and work is on helping patients recover from hypothyroidism. Paul has accumulated a wealth of knowledge on thyroid and adrenal dysfunction and their treatment. His three books cover all of this.

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  1. Helena on 11th January 2021 at 6:14 pm

    Hello and thank you for all the info and research you do on this topic. As a newly (1 week) athyreotic patient (thyroidectomy due to longstanding Graves), the first question I posed myself when handed the Sythroid was, “My thyroid, as diseased as it was, produced both T4 and T3- so why put me at immediate disadvantage vs. a natural state by relying 100% on conversion instead of supplementing with some T3?” I am not even sure if that’s the right question to ask- and I know it’s far from the only one- but it just stood to logic that T4 only would be inadequate. Hope my body magically compensates while I work up the knowledge and strength to push back.

    I am not sure what the most logical treatment for athyreotics would be? NDT? Is that in proportion to the T3/T4 healthy thyroid production though? Synthetic T3 + synthetic T4 compounded to a 20/80 to approximate normal thyroid production? And what of testing? I know fT3 testing is a must… But if docs insist on mono L-T4, how can fT3 ever be driven up to close to its normal ref range?… Any experience with this or insight would be really appreciated.

    • Paul Robinson on 12th January 2021 at 10:24 am

      Hi Helena, thank you for the thoughtful question.
      There is no way to know before treatment what the right thyroid treatment is for the athyreotic thyroid patient. The variation of conversion capability between thyroid patients varies so greatly. The individual thyroid capability also varies hugely – so the level of T3 production and T4 to T3 conversion lost through thyroidectomy will differ enormously.
      The safest and easiest way to go about things would be to begin using T4 meds but be prepared to increase them regardless of TSH level (being very low on TSH when on thyroid meds does not imply the person if hyper) as long as there are no hyper symptoms and FT3 does not go high.
      If this does not fully resolve symptoms the next step would be to use a combination of T4 and T3. Now, NDT has a fixed ratio of T4 to T3. This might not work so a synthetic combo would give the flexibility to reduce T4 and add T3 to attempt to resolve symptoms – which is obviously the main goal rather than just getting numbers ‘in range’.
      Hope this helps.
      Best wishes, Paul

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