Dr Niamh Houston advises a reader on various treatment which help regulate an underactive thyroid.

Dear Doctor,

I've been told I have an underactive thyroid gland. I feel well in myself apart from being tired. I would like to know if iodine supplements would help, I already take calcium supplements for brittle bones?

A- Your thyroid is a small, butterfly-shaped gland located at the base of the front of your neck, just below your Adam's apple. Sometimes your thyroid gland doesn't produce enough hormones, which can upset the balance of chemical reactions in your body.

An underactive thyroid seldom causes symptoms in the early stages, but over time, if not treated, hypothyroidism can cause a number of health problems, such as obesity, joint pain, heart disease and infertility.

Some of the symptoms people experience include fatigue, constipation, increased sensitivity to cold, a puffy face, hoarse voice, high cholesterol, depression, unexplained weight gain, muscle aches and stiffness, as well as heavier than normal periods. If you have any of these symptoms see your GP. A simple blood test measuring your thyroid hormone levels will help diagnose an underactive thyroid. Although anyone can develop hypothyroidism, it occurs mainly in women older than 50.

The standard treatment is to replace the low levels of thyroid hormone with levothyroxine (synthetic thyroid hormone). This tablet is taken daily and after one to two weeks of starting treatment, you should notice that you're feeling less tired.

Your doctor will check your thyroid levels after two to three months and once a normal level has been restored, a blood test every six to 12 months will be enough. This is to make sure you're receiving the correct dose of medication. Over time the dose needed to keep your thyroid functioning normally can change.

Deficiency

Severe iodine deficiency can cause an underactive thyroid. However, this is very rare in developed countries since iodine has been added to salt and other foods.

Taking iodine or kelp supplements will not help regulate an underactive thyroid.

Take your calcium supplements at least four hours before or after levothyroxine as calcium supplements can interfere with its absorption.

Other supplements, medications and even some foods can affect your ability to absorb levothyroxine.These include iron supplements, antacids which contain aluminium or magnesium, walnuts and soy products.

- Niamh Houston