Individuals with ‘normal’ thyroid function may still have symptoms of low thyroid function

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The thyroid gland is the ‘master regulator’ of the body’s metabolism. Should its function falter (hypothyroidism) it can give rise to a wide range of symptoms including dry skin, dry hair, fatigue, weight gain, sensitivity to cold, cold extremities and low mood or depression. Standard blood tests for thyroid function include thyroid stimulating hormone (TSH) and thyroxine (also known as T4). Thyroxine is one of the major hormones made by the thyroid. TSH is made by the pituitary gland, and stimulates the thyroid to make thyroid hormones. In the world of conventional medicine, a raised TSH coupled with low T4 would signal hypothyroidism, and would usually trigger treatment (with thyroxine, usually).

We doctors tend to rely quite heavily on TSH levels to make the diagnosis of low thyroid and monitor treatment. However, for a variety of reasons, I believe TSH is not to be utterly relied upon when making treatment decisions. I wrote about this a couple of years back here.

I was thinking about this today when I came across a study this week that focused individuals with a condition known as Hashimoto’s thyroiditis [1]. This condition is autoimmune in nature, which means its characterised by the body’s immune system reacting against the thyroid. The diagnosis is usually made on the basis of the clinical picture as well as blood tests for antibodies that the body can make that damage the thyroid. The two antibodies that are usually tested are known as anti-thyroid peroxidase and anti-thyroglobulin. Even if one or both of these is positive, treatment will not normally be initiated for low thyroid function unless there is the presence of a raised TSH levels and possibly a low T4 level too.

However, some (though not many) doctors argue that treatment should be tried in individuals with positive antibodies if symptoms suggest low thyroid even if TSH and T4 levels are ‘normal’.

In the study in question, individuals with Hashimotos were identified (defined by the researchers as individuals with anti-thyroid peroxidase levels of greater than 121.0 IU/mL. These individuals were quizzed for the presence of thyroid-related symptoms such as chronic (long-term) fatigue, dry hair, chronic irritability, chronic nervousness, and lower quality-of-life. Compared to individuals in whom there was no diagnosis of Hashimoto’s disease, those with positive antibodies had a significantly higher level of symptoms suggestive of thyroid dysfunction.

TSH levels, on the other hand, did not differ between the two groups.

One way of interpreting this is that individuals with Hashimoto’s thyroiditis have a fair chance of exhibiting hypothyroid symptoms even when their blood tests are ‘normal’.

In recent months I became aware of a book which is about Hasimoto’s thyroiditis, the different ways it can present, and how it might be treated. Those who feel they may have a particular problem in this area may get a lot out of reading this book. You can learn more about it, as well as the doctor who wrote it (Dr Datis Kharrazian) here.


1. Ott J, et al Hashimoto’s Thyroiditis Affects Symptom Load and Quality of Life Unrelated to Hypothyroidism: A Prospective Case–Control Study in Women Undergoing Thyroidectomy for Benign Goiter. Thyroid 2011;21(2):161

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