Letter sent to: All NHS endocrinologists and general practitioners (November 2005)

Dear Doctor

RE: Thyroid Function Tests Guidelines

I would like to draw your attention to the first consultation draft of the proposed UK Guidelines for the Use of Thyroid Function Tests. The draft is now available to read and/or download at http://www.british-thyroid-association.org/news.htm and comments on this are invited by 23rd December 2005.

TPA-UK is at a loss to understand why BTA are recommending doubling the upper level of the TSH test to 10mU/L when the American Academy of Clinical Endocrinologists (AACE), the nation’s largest organization of thyroid specialists, has taken the opposite view and confirmed that hypothyroidism, like many other illnesses that affect predominantly women, has been vastly under diagnosed. After a meeting by the AACE, the normal range for thyroid tests was dramatically narrowed, as noted in the AACE press release of January 2003:

Until November 2002, doctors had relied on a normal TSH level ranging from 0.5 to 5.0 to diagnose and treat patients with a thyroid disorder who tested outside the boundaries of that range. Now AACE encourages doctors to consider treatment for patients who test outside the boundaries of a narrower margin based on a target TSH level of 0.3 to 3.0. AACE believes the new range will result in proper diagnosis for millions of Americans who suffer from a mild thyroid disorder, but have gone untreated until now.

“The prevalence of undiagnosed thyroid disease in the United States is shockingly high particularly since it is a condition that is easy to diagnose and treat,” said Hossein Gharib, MD, FACE, and president of AACE. “The new TSH range from the AACE guidelines gives physicians the information they need to diagnose mild thyroid disease before it can lead to more serious effects on a patient’s health such as elevated cholesterol, heart disease, osteoporosis, infertility, and depression.”

This new improved range increased the number of Americans with Thyroid illness from 13 million to approximately 27 million. Unfortunately, over 13 million Americans with thyroid disease remain undiagnosed, and the majority of those receiving treatment are not receiving appropriate levels of medication. Many doctors do not realise that they have not been adequately trained in the proper diagnosis and/or treatment of hypothyroidism, and the subsequent cost in human life and devastating illness is enormous. What makes this especially tragic is how easy treatment and recovery could be if doctors were given the correct information.

Unfortunately this misinformation also extends to our own country, as many of us have found to our cost. We also have a large number of doctors who are not adhering to, or are unaware of, even our own current guidelines. (See below.) Many merely ensure that blood levels are returned to within the reference range (often barely so) with no regard as to what is optimal for their patient. If this is then compounded by extending the reference ranges, as the BTA are suggesting, rather than shortening them, then many of us will either be condemned to a very poor quality existence, with a good likelihood of a reduced life expectancy, or forced to seek alternative means of treatment. This could include the private sector or even self-medicating, neither of which is particularly desirable from either the patients or their GPs point of view.

An article in the BMJ in August 1996 [2] on the management of hypothyroidism and hyperthyroidism states: The correct dose is that which restores the euthyroid state and relieves symptoms. In most patients these will be achieved by a dose of thyroxine resulting in a normal or slightly raised serum thyroxine concentration, a normal serum triiodothyronine concentration and a normal or below normal serum thyroid stimulating hormone concentration.

This is backed up by a representative of the Department of Health [3] who, as recently as 23 rd November 2005, stated that: It is currently considered good medical practice to rely upon clinical history and examination, in addition to blood tests, in the diagnosis of hypothyroidism.

A study of the TSH of 65,000 people in 2000,[4] that further backs up the case for a reduction of the reference range, forms the basis of a very illuminating article on Normal TSH from Thyroid Australia. The TSH graph within this article, reprinted below, has encouraged many medical practitioners to be more flexible in their interpretation of TSH results. Read the full article.

A new research study just released on 18 th November 2005 from the Cardiovascular Research Institute-South Dakota Health Research Foundation and The University of South Dakota School of Medicine [5] shows a link between low thyroid function and heart problems. We provided strong evidence that low thyroid function alone induced in rats eventually can cause heart failure, said Dr. A Martin Gerdes, director of the Cardiovascular Research Institute and co-author of the study. We also discovered that low thyroid function severely impaired cardiac blood flow due to a dramatic loss of the hearts small blood vessels (arterioles). Within six weeks after inducing low thyroid function in rats, half of the hearts small arterioles were gone. This study in rats is giving researchers hope that more aggressive treatment of hypothyroidism and borderline hypothyroidism will result in a reduction of heart disease in human beings. While further research is needed, these results suggest that low thyroid function has the potential to cause heart failure.

Yet another study in 2005 entitled The Evidence for a Narrower Thyrotropin Reference Range Is Compelling[6] came to the conclusion: It has become clear that previously accepted reference ranges are no longer valid as a result of both the development of more highly sensitive TSH assays and the appreciation that reference populations previously considered normal were contaminated with individuals with various degrees of thyroid dysfunction that served to increase mean TSH levels for the group. They further stated that: Importantly, data indicating that African-Americans with very low incidence of Hashimoto thyroiditis have a mean TSH level of 1.18 mU/liter strongly suggest that this value is the true normal mean for a normal population.Recognition and establishment of a more precise and true normal range for TSH have important implications for both screening and treatment of thyroid disease in general and subclinical thyroid disease in particular.

TPA questions the reliance on diagnosing by TFTs alone. There have been many changes in thyroid tests over the years. Tests should be used as part of a clinical picture and not form the sole criteria for diagnosis

Each of these tests was hailed as the definitive test at the time but was found to be imperfect.(1) The metabolic rate was measured while the patient ran on a treadmill. (2) The next new test measured protein-bound iodide (PBI). (3) The T4-level thyroid test was then developed. (4) The T7-level test was devised, and then (5) the thyroid-stimulating hormone (TSH) test came along. Modern medicine is now into the fourth generation of TSH tests, and with each new test, doctors have noted that they have missed many patients with under active thyroid. It is very obvious that the current method of testing still misses many patients with under active thyroids. Therefore, doctors must treat the patient, NOT the blood test.

TPA is asking all doctors to take note of these recommended new guidelines, which, if implemented, would have a devastating effect upon the lives of the many thousands within the population who are suffering from hypothyroidism, and who would remain undiagnosed and/or under-treated as a consequence.

Yours sincerely

Sheila Turner
Thyroid Patient Advocate

References :
1) AACE 2003 Campaign Encourages Awareness of Mild Thyroid Failure, Importance of Routine Testing. http://www.aace.com/pub/tam2003/press.php 2) Consensus statement for good practice and audit measures in the management of hypothyroidism and hyperthyroidism (BMJ 1996;313:539-544, 31 August).http://bmj.bmjjournals.com/cgi/content/full/313/7056/539 3) Matt Bolton, Customer Service Centre, Department of Health. Ref. Ref:DE00049269. 4) T Bjro et al, ‘Prevalence of thyroid disease, thyroid dysfunction and thyroid peroxidase antibodies in a large, unselected population. The Health Study of Nord-Trndelag (HUNT).’ European Journal of Endocrinology 2000 143 639-647. http://www.eje.org/eje/143/eje1430639.htm 5) Yi-Da Tang et al, Low Thyroid Function Leads to Cardiac Atrophy with Chamber Dilation, Impaired Myocardial Blood Flow, Loss of Arterioles, and Severe Systolic Dysfunction. This Cardiovascular Research Institute (CRI) study is published in the Nov. 15 issue of Circulation, the journal of the American Heart Association. The study can be viewed online at: http://circ.ahajournals.org/. The news article is at: http://www.newswise.com/articles/view/516245/ 6) Leonard Wartofsky and Richard A Dickey, The Evidence for a Narrower Thyrotropin Reference Range Is Compelling The Journal of Clinical Endocrinology & Metabolism Vol. 90, No. 9 5483-5488 http://jcem.endojournals.org/cgi/content/abstract/90/9/5483