Armour thyroid is a brand of natural desiccated thyroid extract made by Forest Laboratories in the United States.
Natural desiccated thyroid tablets are made from raw pork thyroid glands collected at slaughterhouses, which are tested for absence of Salmonella and E. Coli, then held in a frozen state until they are delivered to the processing laboratory where they are minced, placed in a vacuum dryer, defatted, then milled to a fine powder before being packaged. Samples are tested for chemical and microbiological characteristics.
The manufacturers state that the following are the ingredients of Armour:
Active ingredients: T3 and T4
Inactive ingredients: calcium state, dextrose, microcrystalline cellulose, sodium
starch and opadry white
We have written on several occasions to the manufacturers to ask for confirmation of their ingredients and for details of their quality control procedures but have received no reply to date.
Desiccated thyroid extract is not currently licensed in the UK and was withdrawn from use in the UK in the 1970s after synthetic thyroxine had been developed. At that time there was perceived to be a problem with the quality control of thyroid extract with large variations from batch to batch, due to the variation in T4 (thyroxine) and T3 (triiodothyronine) that it contained.
There is concern amongst some doctors over the substantial fluctuations in T3 levels in blood of patients treated with Armour and the potentially harmful effects on the heart (rapid irregular heart beat which predisposes to clots forming inside the heart and then causing strokes) and bones (osteoporosis).
It is difficult to monitor treatment containing a combination of T3/T4 because of peaks and troughs in T3. The long-term effects of T3, Armour, or combinations of T3 and T4 are not known. T3 has a short half-life of a few hours. Patients on T3 have fluctuating T3 levels and at times these may go beyond the upper limit of normal. By contrast T3 levels in patients on thyroxine are stable. Monitoring thyroid hormone replacement in patients on T4 is easy biochemically because of the stable levels. In someone on T3 or Armour it will depend on the time since the last dose.
The Medicine and Healthcare Products Regulatory Agency (MHRA), the licensing authority for pharmaceuticals in the UK and executive agency of the Department of Health, states that natural thyroid products including Armour are not currently licensed in the UK. Any hormone preparation would be classed as a medicine in the UK. As a result they can only be marketed if they have been fully assessed for safety, quality and efficacy by the MHRA and granted a marketing authorisation or product licence. The MHRA does not object to importation of desiccated thyroid extract products provided that they are approved by the United States' Food and Drugs Administration (FDA), standardised to the specification of the United States Pharmacopoeia (USP), and that they are authorised, prescription-only medicine for the treatment of patients with thyroid diseases for whom the UK-licensed synthetic thyroid hormones are not suitable. The MHRA says that it is the decision of each individual PCT as to whether an unlicensed product, in this case Armour, be available on NHS prescription or private prescription (MHRA, Jan 2005). If it is prescribed on an NHS prescription, the patient qualifies for medical exemption because the treatment is for hypothyroidism. Being unlicensed in this country, the doctor would be required to take full responsibility for any adverse effects of the treatment.
The Medicines Act makes provision for doctors to prescribe an unlicensed medicine to meet the needs of an individual patient, on their own responsibility, where they judge the benefit to the patient is justified and outweighs the risk of the unlicensed product. Therefore, the prescription of Armour is a question of clinical judgement on the part of each patient's GP. It is the responsibility of NHS Primary Care Trusts to fund supplies of medicines in their area, whether on a trial or permanent basis. Therefore the decision to provide Armour free from prescription charges would be taken by the GP in consultation with the local PCT.
The BTF sees synthetic thyroxine as the current first-line treatment of hypothyroidism. Current medical practice is governed by evidence. There is no known research showing that porcine thyroid extract is superior to synthetic thyroxine. On the contrary, there are good data that life-long treatment with synthetic thyroxine is safe.
The BTF understands that there are concerns about the use of Armour thyroid because of the rapid fluctuations in T3 levels, the difficulties in monitoring such treatment, uncertainties about the long-term health consequences and the considerably higher costs of such treatment.
The major professional thyroid organisations and published peer-reviewed guidelines on treatment of hypothyroidism recommend thyroxine as the treatment of choice for hypothyroidism and our position is in keeping with this view.
We believe that patients who feel unwell on thyroid hormone treatment merit assessment by a qualified, accredited endocrinologist. Such a management pathway will ensure that thyroid hormone replacement is optimal, other causes of symptoms are considered and a meaningful exploration of the potential risks and benefits of unproven therapies such as Armour can be explored.
We do not consider natural thyroid extract to be suitable for everyone but acknowledge that patients for whom synthetic thyroxine is judged not to be suitable on clinical grounds may, together with their doctor, wish to explore treatment with Armour.
We acknowledge that some doctors, acting out of the best possible interests in the well-being of their patients, and basing their judgement on current research evidence, may be reluctant to prescribe Armour.
Much of the debate about the use of Armour relates to individual accounts of patients who are convinced that switching from thyroxine to Armour has transformed their lives. Doctors are equally aware of patients who have found this treatment unhelpful and some have felt worse than on thyroxine. We feel that it is important to keep an open mind about alternative thyroid hormone replacement regimens to thyroxine, but these issues can only be addressed by a properly conducted prospective randomised controlled trial.