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BTA on Armour -v- Thyroxine Only Therapy [TPA Response]

March 2008 – Thyroid Patient Advocact (TPA) Response to:

A Statement from the British Thyroid Association Executive Committee on Armour Thyroid

“As often in the history of science, the biggest obstacle in finding the truth is not the difficulty in obtaining data, but the bias of the investigators on what data to chase and how to interpret them.”

-Peter H. Duesberg, PhD, Inventing the AIDS Virus Washington, DC, Regnery Publishing, Inc.,


Thyroid Patient Advocacy-UK (TPA-UK) disagrees with many of the statements made by the Executive Committee of the British Thyroid Association (BTA) on natural desiccated porcine thyroid extract (Armour Thyroid, USP). TPA-UK are very concerned that the BTA continue to advise that L-thyroxine (T4) replacement remains the treatment of choice despite the amount of evidence contrary to their opinion, showing it to be ineffective in relieving many patients’ symptoms.

Conventional medical practitioners have made no attempt to evaluate the evidence regarding the use of natural thyroid hormone, and their wholesale dismissal of the concept represents, at least in part, a biased attitude.

History of Thyroid Hormone Treatments

In 1875, Sir William W. Gull published his study of five women suffering from what he called myxoedema.

Sixteen years later, a successful attempt was made to implant a sheep thyroid gland under the skin of a woman suffering from myxoedema. This case was reported in the journal La Semaine Medicale by Betancourt, Lisbon, Portugal on 18th August 1890.

One year later, myxoedema was successfully treated with enteral and parenteral administration of both thyroid glands and thyroid extract.

Immediate improvement was seen after implantation of the sheep thyroid gland, and it became obvious that the beneficial clinical effect was due to a biological active compound released by the implanted sheep thyroid gland into the patient. In July 1891, based on a review of the literature, George R. Murray presented his observations at the Annual Meeting of the British Medical Association (BMA) of a female patient with myxoedema who had been treated successfully with hypodermic injections of extract from the thyroid glands of sheep.

One year after Murrays publication, physicians Fox and MacKenzie reported that oral administration of fresh sheep thyroid gland and thyroid extract were effective in reversing the signs and symptoms of hypothyroidism in a female patient.

The reports from MacKenzie and Fox were published back-to-back in the October 1892 issue of the British Medical Journal (BMJ). Following this publication, oral preparations of thyroid extracts became available and were widely used to treat hypothyroidism successfully.

Based on his research, Bauman (1895) concluded that the active substance in the thyroid gland contains iodine. He attempted, unsuccessfully, to hydrolyze thyroidal proteins in order to isolate the active principle. Following Baumans publication in 1895 reporting high concentrations of iodine tightly bound to proteins in extracts of the thyroid gland, thyroid extracts were standardized to contain 0.2% iodine in order to maintain equal potency of different preparations.

In 1915, Kendall succeeded in hydrolyzing thyroid proteins into simpler constituents.

Further purification yielded a biologically active iodine-containing substance, which was crystallized into a pure form. Kendall called this crystallized product thyroxine. He wrote: In brief, the compound containing iodine, the presence of which, as a normal constituent of the thyroid, as foretold by Baumann 19 years ago, has been isolated in pure crystalline form, and further, it has been shown that this compound is the substance in the thyroid which is responsible for the physiologic activity of the gland.
Unfortunately, Kendall incorrectly concluded that the structure was triioexahydroxyindole propionic acid.

In 1926, Dr. C. R. Harrington of University College London showed that thyroxine is the tetraiodo derivative of thyronine, and he was able to synthesize the active compound.

The Deliberate Hoax

Thyroid extracts continued their popularity and were not affected by the introduction of synthetic thyroxine in the 1930s until a hoax batch of thyroid extract, containing only iodine with no thyroid hormone, was shipped to Europe and the US in 1963, with the goal of discouraging the use of thyroid extracts. This hoax made thyroxine the only eligible thyroid preparation for hypothyroidism because the iodophobic domino effect of the 1948 Wolff-Chaikoff publication prevented physicians from supplementing their patients with iodine.

Many doctors were reluctant to switch to thyroxine only, preferring to prescribe the desiccated gland. They were, however, eventually persuaded to change their allegiance. In 1969, Dr. Wolff from the National Institute of Health published his paper titled, Iodide goiter and the pharmacologic effects of excess iodide.

In 1970, Goodman and Gilman stated,

This episode gave thyroid a bad name because several publications about the unreliability of thyroid appeared before the hoax was uncovered.

There was widespread concern that the effects of this drug were not consistent with previous clinical experience and so all thyroid extract was labelled unreliable. Although the hoax was uncovered seven years later and The Medical Letter in 1973 maintained that desiccated thyroid extract had never been unreliable, mud sticks, and doctors started using synthetic l-thyroxine.

To quote Derry . . . by 1976 about half (52%) of the prescriptions written for thyroid hormone in the United States were for desiccated thyroid or other natural products.”

The best pharmacological authorities confirmed desiccated thyroid remains a remarkably clinically, predictable safe and effective preparation which is well absorbed. So why the continued misinformation perpetrated by the BTA?

BTA Statement

Armour Thyroid contains both thyroxine (T4) and tri-iodothyronine (T3) extracted from the thyroid gland of pigs. One grain, about 60 mg, of desiccated pig thyroid extract contains about 38mcg of T4 and 9mcg of T3, a ratio of around 4 to 1. The normal concentration of these hormones in the human thyroid is, however, at a ratio of 14 to 1. In other words, Armour thyroid extract contains excessive amounts of T3 relative to T4 when used to replace thyroid hormone in man. Moreover, as pig thyroid contains other substances apart from T4 and T3, Armour Thyroid is not a pure preparation of thyroid hormones. Historically, extracts of animal thyroid glands were the only way to treat thyroid underactivity, but since the 1950s pure synthetic thyroid hormones have been available in tablet form (thyroxine sodium [T4] and liothyronine [T3]).

. All thyroid hormone products, both animal-derived and synthetic, are unstable compared to many other drugs. Thyroid hormones consist of iodine atoms bound to the amino acid tyrosine. The iodine atoms easily separate from the tyrosine.

Therefore, it is prudent for both doctors and patients to be vigilant for sub-potent tablets or capsules. There is no evidence showing that thyroxine sodium and liothyronine are more stable than Armour thyroid. The BTA statement causes confusion for doctors, often to the detriment of patients. It is the belief of TPA-UK that such statements by the BTA should be evidence-based and TPA therefore supply herewith the references to support their claims.

It appears that some NHS doctors do not recommend Armour thyroid because they believe the amount of thyroid hormone varies between batches and/or they believe the higher ratio of T3 to T4 in Armour could be harmful or cause adverse reactions. The evidence does not support such reasoning, and in fact the variation of thyroid hormone in Armour is minimal and well controlled (maximum 5-10 %) as specified by the US FDA.

There are many thyroid extract preparations and the trademark Armour Thyroid should not be used as a generic name for these. There is much evidence that Armour Thyroid is the most reliable of the desiccated thyroid preparations in the US.

Evidence is presented in the Empirical use of Armour thyroid by Gaby that many people have hypothyroidism undetected by laboratory thyroid-function tests, and cases are reported to support the empirical use of Armour Thyroid. Clinical evaluation can identify individuals with sub-clinical hypothyroidism that is likely to benefit from thyroid-replacement therapy. In a significant proportion of cases, treatment with thyroid hormone has resulted in marked improvement in chronic symptoms that had failed to respond to a wide array of conventional and alternative treatments. In some cases, treatment with desiccated thyroid has produced better clinical results than levothyroxine. Research supporting the existence of sub-clinical hypothyroidism is reviewed, and the author’s clinical approach to the diagnosis and treatment of this condition is described.

Armour Thyroid does have a higher amount of T3 compared to T4 than the relative amounts of T3 to T4 secreted by the human thyroid gland, however it is well documented that Armour is often more effective and is better tolerated than synthetic preparations of T4, T3 and T4/T3 combination.

This is because the T3 in natural thyroid extract is absorbed more slowly than synthetic (purified, unbound) T3.

The normal thyroid gland contains approximately 200 mcg of T4 per gram of gland, and 15 mcgs of T3 per gram. The ratio of these two hormones in the circulation does not represent the ratio of the thyroid gland, since about 80% of peripheral T3 comes from monodeiodination of T4. Peripheral monodeiodination of T4 also results in the formation of reverse T3, which is iatrogenically inactive.

A similar ratio can be obtained by prescribing both Armour and synthetic thyroxine, although clinical response and symptom control should take precedence over a theoretical ideal.

Perhaps the ultimate form of thyroxine for difficult patients is whole thyroid extracted from nimals, such as Armour thyroid tablets.

The long history of successful use thyroid extract in America has seen natural thyroid extract products successfully compete with the heavily promoted synthetic T4 and T3 preparations. Not only are whole glandular extracts often superior to T4 for the treatment of hypothyroidism, but there is evidence to suggest that such products are also superior to combined T4/T3 preparations.

Shames and Shames report a patient who was treated unsuccessfully with a combination of T4 and T3 who experienced a dramatic improvement when switched to Armour thyroid extract.

When synthetic T4 and T3 first became available, Arem reports the considerable difficulties he experienced when switching patients from thyroid extracts to the new synthetic preparations.

According to Arem, “The new treatment was seldom entirely successful.” Arem continues “Once switched from these natural T4/T3 tablets to T4 tablets, patients complained of sluggishness, decreased memory, impaired concentration, and a host of symptoms of ill-being. This was in spite of having reached normal blood levels of thyroid hormone and TSH.”

Since at least a third of treated hypothyroid patients whose blood tests have been restored to “normal” continue to have symptoms, therefore modern thyroid treatment is often unsuccessful, a fact which is hardly surprising given the fact that triiodothyronine (T3) is the crucially important active thyroid hormone; and the commonly seen failure to convert T4 to T3 (and also, to a lesser extent T2) will result in an unsatisfactory treatment outcome.

This underlines the urgent need to rethink methods of thyroid treatment. Clearly, much greater priority must be given to a symptomatic approach and the importance of how the patient feels, given the relative ineffectiveness of T4 and the dubious usefulness of the serum TSH test alone for diagnosis. Over reliance on laboratory tests, without clinical evaluation, may lead to considerable diagnostic errors.

Since thyroid replacement therapy should aim to reproduce as closely as possible the natural secretions of the thyroid gland, there should be more support for the use of whole thyroid extracts. To this end the effectiveness of whole thyroid extract versus synthetics should be compared in clinical trials, especially involving problematic patients.

BTA Statement:

The concentration of thyroid hormones in Armour Thyroid USP is regulated by the manufacturer to United States Food and Drug Administration (FDA) standards. Despite this, there have been significant problems with the stability of Armour Thyroid in recent years, prompting a massive recall of tablets. Because of these stability problems with Armour Thyroid, there is potential for fluctuations in thyroid hormone levels in the blood of patients treated with Armour Thyroid. These fluctuations may be unpredictable and have adverse effects on patients health.”

TPA. In a 2005, sample testing of several batches of Armour found that some of the samples were not maintaining full potency.

These were manufactured between March and August 2003, and were set to expire between March and August of 2005. To avoid potential problems, it was decided to recall all the Armour made during that timeframe in 2003. A Forest Pharmaceuticals spokesperson stated that very little of the recalled product remained in circulation at that time. Interestingly though, other evidence has shown variation of T4 in synthetic thyroxine to be greater than 30% in some batches.

In a 1980 study, a number of manufacturers other than Forest Pharmaceuticals had versions of desiccated thyroid that were found to be unreliable in potency. The amounts of T4 and T3 in Armour Thyroid, USP were found to be constant. Moreover, two-year old and fresh tablets of Armour Thyroid contained similar amounts of T4 and T3.

The response by Richheimer and Jensen should serve to correct any misrepresentations (implied or otherwise) regarding the liothyronine and levothyroxine content in Armour and the nature of the collaborative study for the U.S. Pharmacopeia. As determined by Armour Pharmaceutical Company and other participating laboratories, the liothyronine and levothyroxine content in Armour is well within the specifications set by the U.S. Pharmacopeia.

The single reference the BTA executive has used to support their Statement on Armour is the Federal Drugs Administration (FDA) withdrawal notice of Armour.

If this withdrawal is evidence against the use of Armour Thyroid, the same argument follows for synthetic thyroxine. There have been previous reports of many defects in the commercial T4 alone preparation over the years.

The FDAs letter to the manufacturers of Synthroid (Eltroxin UK) summarises all the dangers of inconsistent dosing for hypothyroid patients. In particular, they state: “. . . patients using Synthroid have experienced significant, unintended variations in their doses of levothyroxine sodium. . . these variations are not conducive to proper control of hypothyroidism.”

In 2005, endocrinologists had expressed concern about the performance of levothyroxine sodium. As a result, FDA requested product stability data from manufacturers of all approved products manufactured between July 2003 and June 2005. In 2006, FDA presented the data at a joint meeting of the Endocrine and Metabolic Drugs Advisory Committee and the Advisory Committee for Pharmaceutical Sciences. The purpose of the meeting was to discuss the potency and stability of marketed levothyroxine products. In October 2007, FDA announced that it was tightening its potency specifications for all levothyroxine sodium to ensure the drug retained its potency over its shelf life. The FDA has taken this action in response to concerns that levothyroxine sodium potency may deteriorate prior to its expiration date.

Many millions of patients throughout the world have used and continue to use natural thyroid extract. Before the advent of the TSH test in the early 1970s, patients used these products in much higher dosages than nowadays.

There is no evidence to show that patients were harmed by these higher dosages.

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