What is hyperthyroidism?
The thyroid is a butterfly shaped gland which sits in front of your windpipe, just below your Adam's apple (voice box or larynx). Your thyroid uses iodine from your diet to make two main chemicals called thyroid hormones, which are carried in the blood stream to other tissues in the body where they regulate the metabolic rate.
Hyperthyroidism is over activity of the thyroid which occurs when the gland makes too much thyroid hormone for the body's needs. This speeds up your metabolic rate up and therefore every organ in the body works faster. You may have any or all of the following symptoms:
- Fidgety, irritable and on edge
- Increased appetite but loss of weight
- Tremor, feeling hot and sweaty
- Heart racing, palpitations
- Irregular periods
- Some people simply feel tired.
One in twenty patients may notice changes to their eyes, usually with puffiness of the eyelids, a gritty sensation in the front of the eyes and sometimes a 'staring' appearance. Rarely the changes can be more severe, making the eyes very prominent and causing double vision. If this happens you will need to see an eye specialist who may recommend treatment with steroids, an operation or radiotherapy. It is known that smokers are more likely to get eye changes than those who do not smoke.
What does this involve?
Our usual practice to use tablets to control your thyroid gland and to quickly make you feel better. The course of treatment varies from six to eighteen months before the tablets are stopped to see if your thyroid has returned to normal. If over-activity returns we would restart tablets and then discuss either radioactive iodine treatment or thyroid surgery as a second line treatment (see separate treatment pages for information). The tablets that can be prescribed are:
Carbimazole (also called Neomercazole) - This tablet reduces the amount of thyroid hormone being made by the thyroid gland and takes two to three weeks to become fully effective. Usually a higher dose is used at the start (20 to 40 mg once daily) and then the dose is progressively cut down to a maintenance dose (5 to 10 mg daily).
Very occasionally a higher dose is started and maintained (60 mg daily). This then has to be supplemented by a thyroid hormone tablet (Thyroxine) to maintain normal thyroid hormone levels in the blood stream. This is called the 'block and replace' regimen.
Propylthiouracil (also called PTU) - This acts in a similar way to Carbimazole and is equally effective. It is used more often in women during pregnancy or if women are breast-feeding. A 50mg Propylthiouracil tablet is equivalent to a 5 mg Carbimazole tablet and has to be taken two or three times daily.
When will I recover?
As mentioned, the course of tablets takes between six to eighteen months before a pause in treatment allows other options to be considered.
What risks should I know about?
Most tablets have side effects although in Carbimazole and Propylthiouracil thesearerare. They may be severe enough to lead to the tablet being stopped:
- Skin rashes
- Aches and pains in the joints
- Bone marrow suppression - this is a very rare (less than 1 in 20,000 cases)
- Weight gain - this is often the side effect that patients most worry about, but it is not really a side effect at all. If you do gain weight on treatment it probably means that the thyroid gland is getting better and that the metabolic rate is slowing down to normal.