An underactive or hypothyroid gland is the commonest thyroid illness, being more common in women than men and increasing with age. The two important thyroid hormones are thyroxine (T4) and tri-iodothyronine (T3).
The production of these hormones is stimulated by another hormone called thyroid stimulating hormone, or TSH. If levels of thyroid hormones drop, the amount of TSH increases to try to manufacture more - the lower the level of thyroid hormone, the higher the TSH level.
What Causes Hypothyroidism?
Possible Causes Of Hypothyroidism Are;
¤ A lack of iodine in the diet (rare in the Western world because iodine is added to table salt).
¤ The thyroid gland is itself attacked by the body - a condition usually called Hashimoto's thyroiditis.
¤ After thyroid surgery e.g. for thyroid cancer.
¤ After a viral illness or pregnancy - this is usually temporary, and may last 3 to 6 months before a full recovery is made.
¤ Certain medications such as Amiodarone or Lithium.
¤ Primary hypothyroidism - the cause in most people. Here, there is no obvious reason for the thyroid hormones being low and the TSH being high.
What Are Signs And Symptoms Hypothyroidism?
If hypothyroidism is mild there may be no symptoms at all, and any symptoms which occur are sometimes ignored by the patient or put down to 'age'. They are all caused by the slowed metabolism of the body, so symptoms usually include some or all of the following;
¤ an intolerance or dislike of the cold
¤ dry skin and dry, coarse hair
¤ a hoarse or 'croaky' voice
¤ weight gain
¤ irregular periods
If left untreated, severe hypothyroidism can cause enlargement of the heart, fluid on the lungs and severe drowsiness. In extreme cases, death may ensue.
Will I have any tests or investigations?
Some cases will be obvious from the history and examination of the patient, but blood tests will be needed to confirm the diagnosis. The raised TSH test result is probably the most reliable indicator here, with T3 and T4 levels usually being low.
Treatment Of Hypothyroidism?
This is a simple replacement of thyroid hormone - thyroxine - in tablet form. Most people will need between 100 and 150 micrograms each day, and young patients are usually able to start on the full dose straight away. In the elderly however, starting with smaller doses is sensible to prevent any heart problems.
What Course Will The Illness Follow?
Most people begin to notice their symptoms fading within a few weeks of starting treatment although some may feel radically improved within a few days. Blood tests will be taken every few weeks while the body is reverting to normal, with the aim being to keep the TSH level at between 0.5 and 5 IU/ml. Once this is achieved, tests can be don every six months to a year.
Can I Do Anything To Help Myself?
If you are taking thyroxine, it is important not to stop taking this because you are feeling better. This treatment is for life.
Tell Your Doctor
1. Do you feel the cold more than you used to?
2. Have you put on any weight?
3. Are you falling asleep in the day?
4. Has your hair become thicker or coarser?
5. Have your bowels been a problem lately?
Ask Your Doctor
1. Am I entitled to free prescriptions?
2. Are there any foods I should not eat?
3. Should I stop taking any herbal or mineral supplements?
4. How long should it be before I am feeling better?
5. How underactive is my thyroid gland?
1. The American Thyroid Association
Address: Townhouse Office Park, 55 Old Nyack Turnpike - Suite 611, Nanuet, New York 10954
Fax: 914 623-3736
Email: admin [at] thyroid.org
Website URL: http://www.thyroid.org/
By Dr Roger Henderson, MB BS Lond., LMSSA Lond.