A brief note of some public statements about the final withdrawal of the UK product, Thyroid, BP. I suspect it summarises the attitude of the time.
However, the fact that those arguing against it do so from the point of view of under-dosing is of great pertinence. They are not saying the idea of it is bad, just that the actual product is sometimes subpotent, possibly markedly.
Much of the more recent criticism focuses on the fact it contains T3, is expensive, and is not licensed. The USA's FDA has demonstrated that it is possible to identify subpotency and issue recalls. And they appear to be working towards formal approval.
Further, patients who understand, and have ready access to suitable testing, can clearly recognise that they are being under-dosed and act. (And the same issue can occur with levothyroxine - for example, poor quality or changed product with different absorption.)
In 1978, the letter pasted and transcribed into text below appeared in the British Medical Journal. One reference (and I have been unable to find an accessible copy of the page(s) referenced), three short paragraphs, eleven signatures. And Thyroid, BP is consigned to history.
The words are no better than anecdote.
The withdrawal of Thyroid, BP in this letter is predicated on the availability of thyroxine and liothyronine. If liothyronine is, in practice, unavailable, that argument fails.
Assertion that the potency of thyroid extract is variable without any evidence that this is not also the case with thyroxine. (Since 1978, we have seen many recalls of thyroxine/levothyroxine around the world due to unacceptable potency, among other reasons.)
Assertion that the shelf-life of Thyroid, BP is dated without any evidence that this is not also the case with thyroxine.
No consideration that different makes might have different characteristics.
No consideration that the change should be to the regime under which Thyroid, BP is managed.
No consideration that a review of the standards, and consequent improvements, might result in better consistency and better shelf-life.
Thyroid extract
SIR, — We write to suggest that thyroid extract (Thyroid, BP) be removed from the British Pharmacopoeia and that its manufacture be abolished.
We continue to see patients who have been diagnosed as having myxoedema and who are being treated with apparently adequate doses of thyroid extract but who are clinically and biochemically hypothyroid. They have subsequently responded to thyroxine.
Although it is never possible to be certain that drugs prescribed are being taken, there is good evidence the potency of thyroid extract is variable and its shelf-life dated. As both active constituents. thyroxine and triiodothyronine, have been available for many years we see no reason for the retention of thyroid extract, which we consider to be dangerous.
W van't Hoff G M Besser
R Hoffenberg J S Staffurth
D R London David C Anderson
R Hall J Jenkins
G F Joplin R L Himsworth
Peter Sonksen
Br Med J 1978; 2 doi: https://doi.org/10.1136/bmj.2.6131.200-c (Published 15 July 1978)
Cite this as: Br Med J 1978;2:200
[i] Martindale: The Extra Pharmacopoeia, ed A Wathe, 27th edn, p1509. London, Pharmaceutical Press 1977.
Thyroid extract
SIR, -In 1960, when I was chairman of the International Thyroid Conference in London, a subcommittee under my chairmanship unanimously recommended that thyroid extract should no longer be used. I therefore support wholeheartedly the letter from Dr W van't Hoff and others (15 July, p 200). Yet the fact remains that in many countries thyroxine is still, after 18 years, unobtainable.
Why?
RAYMOND GREENE
London W1
https://europepmc.org/backend/ptpmcrender.fcgi?accid=PMC1606433&blobtype=pdf
SIR, I refer to the suggestion made by Dr W van't Hoff (15 July, p 200) that Thyroid extract (Thyroid, BP) should be removed from the British Pharmacopoeia.
It will be of interest to your correspondents to know that the British Pharmacopoeia Commission has recommended that Thyroid and its preparations be omitted from the next edition of the British Pharmacopoeia, which is to be published in 1980.
CA JOHNSON
Secretary and Scientific
Director,
British Pharmacopoeia
Commission
London W1
https://europepmc.org/backend/ptpmcrender.fcgi?accid=PMC1606433&blobtype=pdf
Thyroid extract
SIR,-I was surprised that Dr W van't Hoff and his colleagues (15 July, p 200) felt so strongly about thyroid extract. They consider it to be "dangerous." If these authors now subscribe to my view that inadequate thyroid replacement leads to coronary heart disease (CHD) it might theoretically be argued that the possible varying potency of thyroid extract could be dangerous. However, it is the adequate replacement dose rather than the preparation used which is crucial in preventing CHD.
If the patient is symptom free and you do not subscribe to my view that inadequate replacement therapy leads to CHD, thyroid
extract can in no way be considered dangerous.
Many wise doctors will safely continue to give thyroid extract to patients who have been well on it for years. Newly diagnosed myxoedema should be treated with thyroxine (or very rarely triiodothyronine), but elderly women on thyroid extract are not living dangerously.
P B S FOWLER
Charing Cross Hospital, London W6
https://europepmc.org/backend/ptpmcrender.fcgi?accid=PMC1607488&blobtype=pdf
Thyroid extract
SIR, My friend Dr P B S Fowler (26 August, p 636) has, I think, misunderstood the letter from Dr W van't Hoff and his colleagues (15 July, p 200). The danger to which they refer is a negative one. The potency of thyroid extract is very variable and I have on several occasions seen a hypothyroid patient successfully treated with the extract who has suddenly become myxoedematous. The onset of myx-oedema is often so insidious that the risk of coronary heart disease to which Dr Fowler has so often drawn our attention must in such patients be increased.
RAYMOND GREENE
London WI
https://europepmc.org/backend/ptpmcrender.fcgi?accid=PMC1607843&blobtype=pdf
Thyroid extract
SIR, My friend Dr Raymond Greene (16 September, p 832) states that the potency of thyroid extract is very variable and that hypothyroid patients treated with the extract may suddenly become myxoedematous. A far more likely cause for this occurrence than the varying strength of the extract is the patient's failure to take the tablets--compliance, to use the current jargon. Some patients successfully treated with I-thyroxine suddenly become myxoedematous; they have invariably failed to take their tablets.
Patients on replacement I-thyroxine are seen here twice a year or more when serum thyroxine (T4), thyroid-stimulating hormone (TSH), and cholesterol estimations are done.
A raised serum cholesterol concentration is often the first evidence that they are failing to take their full thyroid replacement but a raised TSH value is the most reliable check on compliance and the T4 level falls only in the more foolish patients who repeatedly fail to take their tablets.
My obsession with the correct treatment of hypothyroidism must make tedious reading, but I wish to show that patients given adequate replacement over a three-year period do not subsequently develop coronary heart disease de novo.
P B S FOWLER
Charing Cross Hospital, London W6
https://europepmc.org/backend/ptpmcrender.fcgi?accid=PMC1608182&blobtype=pdf
UK versus USA
The assays used for UK products (Thyroid, BP) were fundamentally different to those used for USA ingredients (Thyroid USP). One grain of Thyroid, BP was NOT equivalent to one grain of Thyroid USP (such as Armour Thyroid).
I suspect that this was not adequately recognised. And this fact alone could have accounted for some of the arguments. A patient changing from Thyroid, BP to (or from) Armour Thyroid - at the same dose in terms of grains - might have felt very different.
If you don't realise this, then it could look like a problem with the products.
More generally, at this time, assays were not done to directly measure the amounts of T4 and T3 in the products. Rather based on total iodine content and how much was protein-bound. While this did change - and is why we see precise identification of T4 and T3 content of most desiccated thyroid products currently available - the older types of assays lasted in use for far too long.
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[i][b]helvella - The End of Thyroid BP[/b]
A brief note of one public statement about the final withdrawal of the UK product, Thyroid, BP. I suspect it summaries the attitude of the time. Includes several extracts and some extra information.
Last updated 10/02/2025[/i]
Link to blog:
https://helvella.blogspot.com/p/helvella-end-of-thyroid-bp.html
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