New research shows it may be safe to have a low TSH level between 0.04 mIU/L and 0.4 mIU/L which is below the normal reference range. The first population based study monitored 16,426 patients who were on thyroid hormone replacement therapy between 1993 and 2001. The research was presented by Graham Leese from the University of Dundee in Scotland, at the Society for Endocrinology BES 2010 in Manchester.
The study looked at how variations in patients’ TSH levels affected their long term health. Patients who had a low TSH as defined above did not show an increased risk of heart disease, bone fractures or dysrhythmias. The findings confirm it may be safe to take higher doses than currently recommended. Some patients only feel well when their TSH is low with thyroid hormone levels at the upper end of the normal reference range.
According to this particular study, patients with a suppressed TSH, which was defined as a level below 0.04 mIU/L and a raised TSH over 4.0 mIU/L, were at an increased risk of heart disease and bone fractures. However newer studies on the osteoporosis controversy show that people on thyroid hormone replacement therapy with a low or even suppressed TSH don’t have an increased risk of osteoporosis.
Yes, it has been well documented that subclinical hypothyroidism or mild thyroid failure can be detrimental to our health. Some people experience classic symptoms when they are in the early stages of thyroid disease, but for some people mild thyroid failure may be associated with symptoms such as depression, anxiety, loss of memory, loss of cognitive function, systolic and diastolic cardiac dysfunction, raised levels of total and LDL cholesterol, an increased risk for the development of atherosclerosis and subtle neuromuscular abnormalities.
Early treatment and optimal treatment of thyroid hormone replacement therapy can reverse these effects and it can also improve the quality of life for many people.
In many cases the opportunity for a proper diagnosis or optimal treatment of hypothyroidism is lost with the current reference range of the TSH, because it is too wide. Large population based studies have shown that people who are in the early stages of thyroid disease are included in the normal reference range.
Experts have been debating about the guidelines of diagnosis and treatment of hypothyroidism for several decades and for many doctors it remains unclear when to treat or not to treat.
The NACB recommended an upper limit of 2.5 mIU/L for the TSH in 2002, https://www.aacc.org/science-and-research/practice-guidelines/thyroid-disease
The AACE published a press release in 2003 which stated that more than 13 million people suffered from thyroid disease in the USA, but remained undiagnosed, because the reference range for the TSH was too wide. As a result a new upper limit of 3.04 mIU/L was recommended for the TSH, http://www.hospitalsoup.com/public/AACEPress_release-highlighted.pdf
In 2012 the AACE took an even more conservative view and recommended an upper limit of 4.12 mIU/L for the TSH, even though it was well established that people with mild thyroid failure could be included in this new recommended reference range for the TSH, https://www.aace.com/files/hypothyroidism_guidelines.pdf
Doctors are therefore urged to use their best clinical judgement and in the latest AACE’s guidelines published in 2012 it is stated that the recommended guidelines may not be appropriate for everyone.
Most experts agree that the upper limit for the TSH should be 2 mIU/L. Blood test results of actual thyroid hormone levels (Free T4 and Free T3) can often provide better information. It needs to be remembered that people with a healthy thyroid have optimal levels of ‘Free T4’ (in the upper third of the normal range). People with lower levels of ‘Free T4’ (but within the normal range) may be in the early stages of thyroid disease regardless of the TSH value.
Therefore treatment should be based on each patient’s individual circumstances and treatment (a therapeutic trial of thyroxine) should be considered for people with lower levels of ‘Free T4’ (within the normal range or below the normal range) and classic signs and symptoms of hypothyroidism especially for;
References:
Spencer, C. et al. (2007). National Health and Nutrition Examination Survey III Thyroid-Stimulating Hormone (TSH)-Thyroperoxidase Antibody Relationships Demonstrate That TSH Upper Reference Limits May Be Skewed by Occult Thyroid Dysfunction: The Journal of Clinical Endocrinology & Metabolism: Vol 92, No 11. (2007). The Journal of Clinical Endocrinology & Metabolism. [online] Available at: http://press.endocrine.org/doi/full/10.1210/jc.2007-0287
McDermott, M. and Chester Ridgway, et al. (2001). Subclinical Hypothyroidism Is Mild Thyroid Failure and Should be Treated: The Journal of Clinical Endocrinology & Metabolism: Vol 86, No 10. (2016). The Journal of Clinical Endocrinology & Metabolism. [online] Available at: http://press.endocrine.org/doi/full/10.1210/jcem.86.10.7959
Asvold, B. et al. (2007). The association between TSH within the reference range and serum lipid concentrations in a population-based study. The HUNT Study. - PubMed - NCBI. [online] Ncbi.nlm.nih.gov. Available at: http://www.ncbi.nlm.nih.gov/pubmed/17287407.
Galofré, J. et al. (2013). The Incidence and Prevalence of Thyroid Dysfunction in Europe: A Meta-Analysis: The Journal of Clinical Endocrinology & Metabolism: Vol 99, No 3. (2013). The Journal of Clinical Endocrinology & Metabolism. [online] Available at: http://press.endocrine.org/doi/full/10.1210/jc.2013-2409.
Hollowell, J. et al. (2002). Serum TSH, T(4), and thyroid antibodies in the United States population (1988 to 1994): National Health and Nutrition Examination Survey (NHANES III). - PubMed - NCBI. [online] Ncbi.nlm.nih.gov. Available at: http://www.ncbi.nlm.nih.gov/pubmed/11836274
Practitioners, T. (2016). RACGP - Hypothyroidism - Investigation and management. [online] Racgp.org.au. Available at: http://www.racgp.org.au/afp/2012/august/hypothyroidism/
Spencer, C et al. (2002) NACB, Laboratory Support for the Diagnosis and Monitoring of Thyroid Disease [online] Available at: https://www.aacc.org/science-and-research/practice-guidelines/thyroid-disease
Garber, J. et al. (2012). ATA/AACE Guidelines – Clinical Practice Guidelines for Hypothyroidism in Adults: Co-sponsored by the American Association of Clinical Endocrinologists and the American Thyroid Association. [online] Available at: https://www.aace.com/files/hypothyroidism_guidelines.pdf
American Association of Clinical Endocrinologists. (2003). Press Release – Over 13 million with thyroid disease remain undiagnosed. [online] EndocrineWeb. Available at: http://www.hospitalsoup.com/public/AACEPress_release-highlighted.pdf
The most common reasons why you may not feel well on thyroxine are as follows;
Most people who are in the early stages of the disease do well on thyroxine only if the dose is right. However studies have shown that people on full replacement therapy are more likely to experience symptoms of an underactive thyroid on thyroxine only.
No, there is no cure, but replacing thyroid hormone is ESSENTIAL. We cannot live without thyroid hormone.
Yes, many thyroid patients have non-coeliac gluten intolerance and some have coeliac disease. If you suffer from bloating, flatulence, malabsorption, tiredness after eating gluten, constipation or foul smelling fatty stools then it may be wise to ask the doctor for a blood test (antigliadin IgG and coeliac panel). You must be on a normal diet before you do the tests, because the tests become negative once you are on a gluten free diet. The diagnosis of coeliac disease is confirmed by a positive biopsy obtained through an endoscopy. Studies have also shown that thyroid antibodies are gluten dependent and decrease on a gluten free diet, but a gluten free diet may not stop thyroid disease from progressing further. However most patients with autoimmune thyroid disease and non-coeliac gluten intolerance (gluten sensitivity) or coeliac disease feel better on a gluten free diet. For more information contact the Coeliac WA, PO Box 726 Bentley WA 6982, located at Unit 2, 4 Queen St, Bentley WA 6102, T: 08 9451 9255, F: 08 9451 9266, Email: This email address is being protected from spambots. You need JavaScript enabled to view it. Web http://wa.coeliac.org.au/
General practitioners can diagnose and treat autoimmune thyroid disease. Sometimes patients are referred to endocrinologists or thyroidologists (doctors who specialize in thyroid disease). For nodules, goitres and thyroid cancer you may be referred to an endocrine surgeon as well.
© 2016 Monique Atkinson
Disclaimer The information provided is for educational purposes only and is not intended to be medical advice. The contents must not be relied upon in place of advice and treatment from a qualified medical practitioner. THYROID WA SUPPORT GROUP INC. and the author disclaim any liability whatsoever.