Reverse T3 - what if my test shows high rT3 and a low T3/rT3 ratio?

Thyroid Health

Here's what you can do about your high rT3 result.


Helen Marsden

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If your thyroid hormones are otherwise normal then a high rT3 level on its own is unlikely to be significant. If you are experiencing symptoms and your thyroid hormones are normal then it is important to discuss them with your doctor as it is possible that a cause other than your thyroid is responsible.

There is no conventional treatment for elevated rT3 but there are a few things you might be able to do for yourself:

1) The first is to see if you can identify if there is another underlying health issue which might be causing your symptoms; if you haven’t already had one we suggest a comprehensive blood test which tests your blood cells, kidneys, liver function, diabetes, iron status and vitamin B12/folate for anaemia, C-reactive protein for inflammation and vitamin D.

2) Optimise your vitamins and minerals.  There is evidence that people with thyroid problems may have lower levels of certain nutrients. Lower levels of selenium are associated with increased rates of hypothyroidism[1] and with the development of some thyroid diseases[2]. Approximately 40% of the UK population have less than the recommended daily intake of selenium in their diets[3]. It is less clear whether selenium supplementation improves thyroid function in people with diagnosed thyroid disease[4].  Iron deficiency is thought to decrease the body’s response to TSH and to cause lower levels of T3 and T4[5]. Zinc supplementation has been shown to improve thyroid hormone levels in overweight or obese people[6].
Vitamin B12 deficiency and pernicious anaemia are common in people with hypothyroidism[7]. Pernicious anaemia is easy to overlook so we recommend testing for it if you are found to have low vitamin B12 levels.
Iodine has a goldilocks relationship with thyroid function – levels that are too low[8] or too high[9] can both interfere with thyroid function. Iodine deficiency is rare in the UK, and some over-the-counter iodine supplements contain high levels which may push your blood levels above the top end of the normal range. Excess supplementation can cause an increase in thyroid antibodies in some people[10].
You can find all these tests on our thyroid page.

3) High levels of thyroid stimulating hormone are associated with high levels of cortisol, the hormone your body produces when stressed[11]. You can check your cortisol levels with a Cortisol Saliva Test. This can detect slight increases in cortisol which are due to high levels of stress, as well as more serious abnormalities of cortisol. Adopting relaxation techniques such as meditation, getting regular and high-quality sleep as well as adopting a healthy diet and exercise plan can do much to relieve stress and correct mild abnormalities in cortisol levels.

While there isn’t sufficient evidence yet about the management of high rT3 and a low T3/rT3 ratio, the suggestions above will help to improve your general health, and to check for other conditions that might be causing symptoms, or impacting on the health of your thyroid. If you are planning to take vitamin or mineral supplements then make sure you keep within the recommended ranges; sometimes too much supplementation can be as harmful as not enough.

You may find practitioners who will prescribe T3 (liothyronine) to improve your symptoms. Please bear in mind that for the majority of people studies show that there is no benefit to taking T3 instead of levothyroxine. People who are struggling to control their thyroid symptoms with levothyroxine alone may experience an improvement when taking T3, however, this needs to be started by a specialist, carefully monitored and managed to make sure that you don’t take more thyroid hormone than you need.

Learn more about thyroid disease:

What is the thyroid?

What is thyroid disease?

What are the risk factors for thyroid disease?

What is hypothyroidism (an underactive thyroid)?

What is hyperthyroidism (an overactive thyroid)?

How is thyroid disease diagnosed?

Reverse T3 - what is it and do I need to test for it?

What are the symptoms of thyroid disease?

Thyroid FAQs

[1] Wu, Q., Rayman, M. P., Lv, H., Schomburg, L., Cui, B., Gao, C., … Shi, B. (2015).
Low Population Selenium Status Is Associated With Increased Prevalence of Thyroid Disease.
The Journal of Clinical Endocrinology & Metabolism, 100(11), 4037–4047.

[2] Drutel, A., Archambeaud, F., & Caron, P. (2013).
Selenium and the thyroid gland: More good news for clinicians.
Clinical Endocrinology, 78(2), 155–164.

[3] Bates, B., Lennox, A., Prentice, A., & Bates, C. (2012).
National Diet and Nutrition Survey, 3(I), 1–79.

[4] Garber, J. R., Cobin, R. H., Gharib, H., Hennessey, J. V., Klein, I., Mechanick, J. I., … Woeber for the American Association, K. A. (2012). Clinical Practice Guidelines for Hypothyroidism in Adults: Cosponsored by the American Association of Clinical Endocrinologists and the American Thyroid Association.
Thyroid, 22(12), 1200–1235.

[5] Zimmermann, M. B., & Köhrle, J. (2002).
The Impact of Iron and Selenium Deficiencies on Iodine and Thyroid Metabolism: Biochemistry and Relevance to Public Health. Thyroid, 12(10), 867–878.

[6] Mahmoodianfard, S., Vafa, M., Golgiri, F., Khoshniat, M., Gohari, M., Solati, Z., & Djalali, M. (2015).
Effects of Zinc and Selenium Supplementation on Thyroid Function in Overweight and Obese Hypothyroid Female Patients: A Randomized Double-Blind Controlled Trial.
Journal of the American College of Nutrition, 34(5), 391–399.

[7] Ness-Abramof, R., Nabriski, D. a, Braverman, L. E., Shilo, L., Weiss, E., Reshef, T., … Shenkman, L. (2006).
Prevalence and evaluation of B12 deficiency in patients with autoimmune thyroid disease.
The American Journal of the Medical Sciences, 332(3), 119–22.

[8] Hu, S., & Rayman, M. P. (2017).
Multiple Nutritional Factors and the Risk of Hashimoto’s Thyroiditis.
Thyroid, 27(5), 597–610.

[9] Laurberg, P., Cerqueira, C., Ovesen, L., Rasmussen, L. B., Perrild, H., Andersen, S., … Carlé, A. (2010).
Iodine intake as a determinant of thyroid disorders in populations.
Best Practice and Research: Clinical Endocrinology and Metabolism, 24(1), 13–27.

[10] Harach, H.R.; Escalante, D.A.; Onativia, A.; Outes, J.L.; Day, E.S. and Williams, E.D. (1985)
Thyroid carcinoma and thyroiditis in an endemic goitre region before and after iodine prophylaxis.
Acta Endocrinol. (Copenh), 108(1), 55-60.

[11] Walter, K. N., Corwin, E. J., Ulbrecht, J., Demers, L. M., Bennett, J. M., Whetzel, C. A., & Klein, L. C. (2012).
Elevated thyroid stimulating hormone is associated with elevated cortisol in healthy young men and women.
Thyroid Research, 5(1), 1.

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