Thyroid FAQs

Thyroid Health

Read our Frequently Asked Questions to get the answers you need to help you understand your thyroid disorder.


Helen Marsden

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Thyroid disorders aren't always easy to diagnose and treat, but the more you learn about how your thyroid functions and what factors can undermine the delicate balance of your thyroid hormones, the better equipped you'll be to manage your condition. 

1. My thyroid hormone blood test showed that my hormone levels are normal but that I have raised thyroid antibodies. What does this mean?

Raised thyroid antibodies mean that your thyroid gland is under attack from your immune system - it is a very common cause of an underactive thyroid (Hashimoto's thyroiditis). If your antibodies are raised but your hormone levels are still within the normal ranges it indicates that your thyroid gland hasn't suffered too much damage and is still able to produce thyroid hormones. Your doctor will normally want to monitor your condition - should your thyroid begin to fail you can be treated with thyroid medication. Raised thyroid antibodies are also seen in almost 80% of Graves' disease sufferers, where an autoimmune response causes the thyroid gland to produce excess levels of thyroid hormones.

2. Can I help my thyroid condition if I eat more foods or take supplements containing iodine?

Iodine is necessary for thyroid function as it is required for the production of thyroxine (T4). However, because most cases of thyroid disease in the UK are caused by damage to the thyroid gland from the body's own immune system rather than a shortage of iodine, eating an iodine-rich diet will probably have little impact. If you are taking replacement thyroid hormones you will not need iodine and supplementing with iodine may actually do more harm than good. People with Graves' disease should not take supplements of iodine or eat iodine-rich foods. In parts of the world where iodine deficiency is more common, it can be a leading cause of hypothyroidism. Foods containing iodine include kelp and other sea vegetables, fish, seafood, milk and eggs.

3. Is it possible to have normal levels of TSH, FT4 and FT3 yet still have a thyroid problem? All my thyroid blood tests are normal but I still suffer from symptoms.

It is not unusual to feel symptoms which could be related to your thyroid even when your thyroid hormones are within the normal ranges. Some people report thyroid symptoms when their thyroid antibodies are elevated, even though their thyroid function is still normal. We recommend regular thyroid monitoring if this applies to you, as many people with elevated antibodies go on to develop a thyroid disorder. There are other conditions which can cause similar symptoms to thyroid disease. Once a thyroid condition has been ruled out, it is possible to investigate other causes of your symptoms.

4. My thyroid blood test results show that I have raised TSH and low T4. What does this mean?

Your blood test results indicate hypothyroidism. A raised TSH (thyroid stimulating hormone) reading means that your pituitary gland is stimulating the thyroid gland to produce more thyroid hormones because your levels of thyroid hormones are too low. This is supported by your low T4 (thyroxine) result. You may wish to have a thyroid antibodies test to confirm the diagnosis and establish the cause - e.g. an autoimmune disease such as Hashimoto's thyroiditis, a common cause of an underactive thyroid.

5. I have been diagnosed with an overactive thyroid. How is hyperthyroidism treated?

The key to treating hyperthyroidism is to prevent the thyroid gland from producing excessive quantities of thyroid hormones. This may be achieved by prescribing anti-thyroid medication such as Carbimazole, by destroying part of the thyroid gland with radioactive iodine, or through a thyroidectomy, whereby the thyroid gland is surgically removed.

6. I have been told that I have sub-clinical hypothyroidism. What does this mean?

Sub-clinical hypothyroidism means that your blood test results show elevated levels of thyroid stimulating hormone (TSH) (indicating that your thyroid is being stimulated to produce more thyroid hormones) but your levels of thyroid hormones (T4 and T3) are normal. This diagnosis raises your risk of becoming hypothyroid so it is important to monitor your thyroid hormones regularly to ensure that any changes which would require treatment are picked up immediately. Other conditions, such as raised cholesterol and inflammation, which are associated with hypothyroidism can also present with sub-clinical hypothyroidism.

7. My thyroid blood tests show that I have low TSH and raised T4. Could this explain why I feel so hot and my heart races all the time?

Yes - these results indicate hyperthyroidism. A low TSH reading means that your pituitary gland detects high levels of circulating hormones in the blood and doesn't need to stimulate the thyroid to produce more. In many cases of an overactive thyroid, your thyroid gland is under attack from your own immune system and it responds by producing more thyroid hormones - levels of T4 become elevated as a result. An overactive thyroid causes many symptoms including raised temperature, rapid pulse, anxiety and tremors.

8. Are there foods that I should avoid whilst taking thyroid replacement hormones?

Some foods are goitrogenic which means that they may contribute to the formation of a goitre. These are foods in the brassica family and include broccoli, cabbage and brussels sprouts. Cooking reduces the impact of goitrogens on thyroid function so the risk of eating them is fairly low. Other foods you should avoid include soya which interferes with thyroxine absorption and foods high in iodine which can make your condition worse. If you are taking iron supplements they too can interfere with the absorption of thyroxine so it is advised to leave at least 4 hours between your medication and taking supplements which contain iron.

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?

Reverse T3 - results explained 

What are the symptoms of thyroid disease?

Medicheck your thyroid

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