Is the Royal College of Physicians and The British Thyroid Association  DELIBERATELY TRYING TO MISLEAD UK medical practitioners and patients into believing no studies have ever been conducted into using thyroid extract versus L-thyroxine only therapy? WHY are both the RCP and BTA deliberately choosing to ignore the recent studies by NHS endocrinologists Das et al., (2007) and Lewis et al., (2008) which found that Armour Thyroid treatment led to resolution of symptoms in certain groups of patients who were left symptomatic on thyroxine-only treatment.(1,2) The RCP, BTA also ignorer older studies into thyroid extract versus levothyroxine?(3-9)

In the six references (used by the RCP to back up their statements), no references have been cited to back up their statements that synthetic T3 should not be used. With out the required medical evidence, their statement is merely opinion.

Thyroid extract was the ONLY available therapy for more than 50 years before synthetic thyroxine was manufactured.  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". (10) So why the continued misinformation perpetrated by the RCP and BTA?

There is much evidence that Armour Thyroid is the most reliable of the desiccated thyroid preparations. 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. Treatment with desiccated thyroid has produced better clinical results than levothyroxine.(11-15) It is also well documented that Armour is often more effective and is better tolerated than synthetic T4, T3 and T4/T3 combination.(16)  This is because the T3 in natural thyroid extract is absorbed more slowly than synthetic (purified, unbound) T3. (17)

Not only are whole glandular extracts often superior to T4 for the treatment of hypothyroidism, there is also evidence to suggest that such products are also superior to combined synthetic T4/T3 preparations.(18,19)

Hypothyroid patients who still suffered classic symptoms of hypothyroidism on T4 only treatment, and who were switched to Armour thyroid extract became biochemically euthyroid and completely symptom-free.(20) Also, before the advent of the TSH test in the early 1970s, patients used thyroid extract in much higher dosages than nowadays.(21)

There are advantages to using Armour that are not related to its T3 content.  Broda Barnes observed some patients treated with syntheticT4/T3 combination continued to experience residual symptoms, particularly dry skin and oedema.  Both symptoms resolved in 1-2 months when the treatment was changed to Armour.(22) . This observation suggests a third active substance is secreted by the thyroid gland. The most likely candidate is 3, 5-diiodo-l-thyronine (T2).  Although little was known about the function of this compound in humans, the widely held assumption that it is metabolically inert may be incorrect.  The fact is T2 is indeed very active in terms of metabolic effects. The manufacturers of Armour Thyroid have done no studies into the specific amount of the other thyroid hormones in Armour, T2, T1, calcitonin or any other 'T' hormones that are naturally occurring in the desiccated thyroid.  Nothing has been removed in the processing and many endocrinologists believe there is little (or no) information about T2 or monoiodothyronine (T1).  However, this is not the case. The use of T2 has been shown to increase hepatic oxygen consumption by about 30%.  The authors of one study discovered only T2 was active in stimulating rapid hepatic oxygen consumption.  They concluded that it acts rapidly and directly through activation of the mitochondria. (23) See also (24-34)

L-thyroxine was introduced without any comparison with natural thyroid extract.  The Medicines Control Agency has continued its use without review.  Given that levothyroxine is the cheaper medication, one has to question why the manufacturers would not wish to demonstrate equal effectiveness.  Natural thyroid extract has been making patients better since 1894. The burden of proof lies with the synthetic manufacturers to demonstrate that it is as safe, effective and as consistent as Armour Thyroid. (35,36)

Regarding the RCP reference  (Baloch Z, Carayon P, Conte-Devolx B, et al. Laboratory medicine practice guidelines. Laboratory support for the diagnosis and monitoring of thyroid disease. Thyroid 2003;13:3-126.)

The RCP and BTA should be aware that thyroid function blood test results can be influenced by MANY factors, any of which should be taken into consideration, e.g.

  
• Labelling errors

  
• Bacterial contamination

  
• Yeast/Fungal contamination

  
• Clotting

  
• Sampling errors

  
• Sample preparation errors

  
• Sample storage errors

  
• Thermal cycling

  
• Antithyroid antibodies (any)

  
• Antibodies from any other cause

  
• Presence of specific 'toxins' in the blood

  
• Presence of pharmaceutical drugs (interferences) within the blood

  
• The method of analysis being carried out e.g. radio-immune assay (RIA)

  
• 'Systematic' errors in analytical equipment or methodology

  
• Composite errors <> pre-analysis (not mentioned above)

  
• MCT8 mutations

Many individuals with classic hypothyroid symptoms are discouraged when they are told their TFT's are within the normal range. The question of whether they might be resistant to their body's own thyroid hormone is seldom considered. Yet, a disease known as thyroid hormone resistance can prevent thyroid hormone from reaching the body's cells.

The discovery of MCT8 mutations explains laboratory discrepancies (37) e.g. cases in which the lab results didn't fit a particular pattern.  It also explains how thyroid hormone resistance can cause TSH to appear normal even with a low FT4.  In many instances only the TSH test is performed. If the TSH result is normal, and symptoms of hypothyroidism are observed, tests for FT4, FT3 and T3 should all be performed.

None of these types of error are ever shown as being part of the reference range, but they all add to the unquantifiable 'unreliability' of the final number that appears on a lab report; stated to be within/outside a reference range. The labs expect, but often don't get, notification of antibodies found by other labs or by investigations showing antibody activity, to enable proper screening (dilutions) for likely errors. e.g. vitiligo, alopecia, ongoing autoimmune symptoms specific to such as lupus, autoimmune attacks on specific organs, histology samples, haematological examinations.(38) A search on Pubmed shows 126 such cases.

The fact that the RCP and BTA have refused to acknowledge the hundreds of references to the studies, research and medical evidence made freely available to them from researchers, doctors and patients throughout the world is both deplorable and unscientific.

References:

1.  "Does synthetic thyroid extract work for everybody"? Das G, Anand S & De P. Endocrine Abstracts (2007)13 P316

  2.  "Improvement in quality of life in hypothyroid patients taking Armour Thyroid. Lewis D, Kumar J, Goulden P, Barnes D. Endocrine Abstracts (2008) 15 P359

  3.  Lavietes, P.H. and Epstein, F.H.: Thyroid therapy of myxedema: A comparison of various agents with anote on the composition of thyroid secretion in man. Ann. Intern. Med., 60:79-87, 1964.

  4.  Gorowski, T., Pucilowska, J., and Wernic, K.: Comparative effects of desiccated thyroid gland and sodium salt of L-thyroxine in the treatment of hypothyroidism. Pol. Tyg. Lek., 44(32-33):768-770, 1989.

  5.  Krenning, E.P., Docter, R., Visser, T.J., et al.: Replacement therapy with L-thyroxine: serum thyroid hormone and thyrotropin levels in hypothyroid patients changing from desiccated thyroid to pure thyroxine substitution therapy. Neth. J. Med., 28(1):1-5, 1981

  6.  Felt, V. and Nedvidkova, J.: Comparison of treatment with L-thyroxine and a dried thyroid gland preparation in patients with hypothyroidism. Vnitr. Lek., 28 (11):1067-1073, 1982.

  7.  Singh, S.P., Feldman, E.B., and Carter, A.C.: Desiccated thyroid and levothyroxine in hypothyroidism: comparison in replacement therapy. N.Y. State J. Med., 72(9):1045-1048, 1972.

  8.  Sawin, C.T., Hershman, J.M., Fernandez-Garcia, R., et al.: A comparison of thyroxine and desiccated thyroid in patients with primary hypothyroidism. Metabolism, 27(10):1518-1525, 1978.

  9.  McGavack, T.H. and Reckendorf, H.K.: Therapeutic activity of desiccated thyroid substance, sodium Lthyroxine and D, L-triiodothyronine: a comparative study. Am. J. Med., 20:774-777, 1956.

  10.  Derry DM. Breast Cancer and Iodine. Trafford Publ., Canada, 2001; 39.

  11.  Steven L. Richheimer, Charlotte B. Jensen. Response to "Liothyronine and Levothyroxine in Armour Thyroid?": 1987.Journal of Pharmaceutical Sciences. Volume 76, Issue 4. Pages 346-347

  12.  Rees-Jones RW, Larsen PR. Triiodothyronine and thyroxine content of desiccated thyroid tablets". Metabolism. 1977 Nov;26(11):1213-8

  13.  Rees-Jones RW, Rolla AR, Larsen PR. "Hormonal content of thyroid replacement preparations". JAMA. 1980 Feb 8;243(6):549-50.

  14.  LeBoff MS, Kaplan MM, Silva JE, Larsen PR. "Bioavailability of thyroid hormones from oral replacement preparations". Metabolism. 1982 Sep;31(9):900-5.

  15.  Gaby AR."Sub-laboratory hypothyroidism and the empirical use of Armour thyroid". Altern Med Rev. 2004 Jun;9(2):157-79

  16.  Hertoghe T, Lo Cascio A., Hertoghe J. "Considerable improvement of hypothyroid symptoms with two combined T3-T4 medication in patients still symptomatic with thyroxine treatment alone". Anti-Aging Medicine (Ed. German Society of Anti-Aging Medicine-Verlag 2003) 2004; 32-43

  17.  Alan R. Gaby, MD "Alternative Medicine Review" Volume 9, Number 2, 2004

  18.  Shames, RL, Shames, KH, Thyroid Power: 10 Steps to Total Health, Harper Collins Publishers, New York, 2001.

  19.  Saravanan, P., et al, Clinical Endocrinology 57 (5), 577-585, 2002.

  20.  Pearch, C.J. and Himsworth, R.L. "Total and free thyroid hormone concentration in patients receiving maintenance replacement treatment with thyroxine". Brit. Med. J., 288: 693-695, 1984.

  21.  Barnes BO. "Is there a third hormone in the thyroid gland? Which preparation should be used for treatment?" J Int Acad Prev Med 1982; November:38-39.

  22.  Horst C, et al. "Rapid stimulation of hepatic oxygen consumption by 3,5-di-iodo-L-thyronine." Biochem J 1989 Aug 1;261(3):945-50

  23.  Lanni A, et al. "Calorigenic effect of diiodothyronines in the rat." J Physiol 1996 Aug 1;494 (Pt 3):831-7

  24.  Goglia F, et al. "Action of thyroid hormones at the cellular level: the mitochondrial target." FEBS Lett 1999 Jun 11;452(3):115-20

  25.  Lanni A, et al. "Effect of 3,3'-diiodothyronine and 3,5-diiodothyronine on rat liver oxidative capacity." Molecular and Cellular Endocrinology. Volume 86, Issue 3. 1992

  26.  Lanni A, et al. J. Endocrinol. 136:59-64 1993.

  27.  O'Reilly I, Murphy MP. Acta Endocrinol. 127:542-546 1992.

  28.  Lanni A, et al. "3,5-Diiodo-L-thyronine and 3,5,3'-triiodo-L-thyronine both improve the cold tolerance of hypothyroid rats, but possibly via different mechanisms." Pflugers Arch 1998 Aug;436(3):407-14

  29.  Varghese S, Oommen OV. "Thyroid hormones regulate lipid metabolism in a teleost Anabas testudineus (Bloch)." Comp Biochem Physiol B Biochem Mol Biol 1999 Dec;124(4):445-5

  30.  J. Kvetny. Horm. Metab. Res. 24:322-325, 1992.

  31.  Moreno M, et al. "Effect of 3,5-Diiodo-L-thyronine on thyroid stimulating hormone and growth hormone serum levels in hypothyroid rats." Life Sciences, Volume 62, No.26, pp. 2369-2377, 1998.

  32.  Horst C, et al. "3,5-Di-iodo-L-thyronine suppresses TSH in rats in vivo and in rat pituitary fragments in vitro." J Endocrinol 1995 May;145(2):291-7

  33.  Baur A, et al. "3,5-diiodo-L-thyronine stimulates type 1 5' deiodinase activity in rat anterior pituitaries in vivo and in reaggregate cultures and GH3 cells in vitro." Endocrinology 1997 Aug;138(8):3242-8.

  34.  Matthews,G. "Armour Thyroid and Porcine Thyroid Extract Replacement Therapy". . June 29.2004.Medicines and Healthcare Products Regulatory Agency MHRA letter

  35.  Barnes, B MD, Hypothyroidism: The Unsuspected Illness, Harper & Row, 1976, pgs 142-144, 178-181

  36.  Willard Owen Thompson, Lawrence L. McLellan, Phebe K. Thompson, and Lois F. N. Dickie "THE RATES OF UTILIZATION OF THYROXINE AND OF DESICCATED THYROID IN MAN: THE RELATION BETWEEN THE IODINE IN DESICCATED THYROID AND IN THYROXINE". Department of Medicine, Rush Medical College, and The Presbyterian.

  37.  William Winter and Neil Harris, A New Type of Thyroid Disease, Advance for Administrators of the Laboratory, June, 2008: 46-50.

38.  Sapin R. [Interferences in immunoassays: Mechanisms and outcomes in endocrinology] Ann Endocrinol (Paris). 2008 Nov; 69(5):415-25. Epub 2008 Jun 5.