Hyperthyroidism
This is over-activity of the thyroid gland such that blood levels of thyroxine are higher than normal. It occurs in 0.5 - 2% of the population and women are 10 times more commonly affected than men.
The clinical features may include:
Grave's disease is an autoimmune condition - the body produces antibodies which react with its own thyroid gland causing increased activity. It usually affects women in their 20's to 40's. Hereditary factors are involved. About 20% will develop eye problems. A small number of patients may develop painless red lumps on the shins and a few have finger nail changes.
TREATMENT
Available treatment includes drugs, radioactive iodine or surgery.
Antithyroid drugs: Carbimazole and propylthiouracil are the most commonly used drugs in Britain. Drugs are used in patients with small goitres, mild disease, children and pregnant women. Most patients need treatment for 12-18 months. Large doses are used to start with and reduced to smaller doses once control has been gained. Some physicians use a 'block and replace' regimen whereby the thyroid is blocked with high doses of drug and small amounts of thyroxine are given to maintain normal levels.
Side effects are uncommon and include rashes, hair loss, itching, fever, joint pains and jaundice. A rare but important side effect is agranulocytosis - this is when the white blood cells in your body are lowered. You may develop a sore throat or mouth ulcers. You must stop your tablets and see your doctor immediately for a blood test.
Some patients with palpitations and tremor may benefit from drugs called beta-blockers, e.g. propranolol.
Some patients may relapse once treatment is stopped - they become overactive again. If the symptoms return, a blood test will confirm the diagnosis.
Radioiodine: This is the simplest, most convenient treatment. It is the treatment of choice for older patients. It is taken by mouth (drink or capsule). The radioactive iodine is concentrated in the thyroid and over time reduces the over-activity. It takes several weeks and you may need treatment with drugs during this time. Another dose can be given if the thyroid remains overactive. Antithyroid drugs have to be stopped for a week before radioiodine is given. They can be started again 7-10 days later.
Radioiodine is safe but it is advisable to avoid close contact with children (i.e. being within 1 metre) for 2-3 weeks after treatment. Radioiodine is not given to pregnant women as it crosses the placenta and may affect the thyroid of the foetus. Pregnancy should be avoided for 6 months after treatment.
Apart from the above precautions, no other safety measures are needed. Disposal of urine is quite safe down the lavatory where it will be diluted to safe levels.
Long-term there is a risk of under-activity of the gland (hypothyroidism).
Thyroid surgery: total or subtotal thyroidectomy is the treatment of choice for younger patients or those with a large goitre, severe disease or those who have relapsed. It is only performed in patients once the over-activity of the gland has been controlled by tablets. Some patients are given Lugol's iodine to make the gland less vascular before surgery.
For details see section on surgery.