GRAVES EYE DISEASE OR
Infiltrative Thyroid Ophthalmopathy
Hyperthyroidism is a condition in which the thyroid gland produces a greater than normal amount of hormone. It occurs in a number of diseases, including Graves’ disease, toxic goitre, thyroiditis and ingestion of excessive amounts of thyroid hormones. Excessive levels of thyroid hormones give rise to weight loss, rapid heart, tremor, sweating and changes in the nails, skin and hair. Subjectively, a person will notice nervousness, heat intolerance and heart palpitations.
Graves’ disease is a term used to describe the commonest variety of hyperthyroidism, which is regarded as having an autoimmune basis. Autoimmune disease may be understood as a process by which the body sees some part of itself as being foreign and reacts to it much the same way that it would with any bacteria or virus. In the case of Graves’ disease, the body sees the thyroid gland as the foreign object and produces antibodies that attack the thyroid gland. This will often (but not in all cases) cause the thyroid gland to become over active. Graves’ eye disease is currently believed to be due to a similar autoimmune reaction. However, in the case of Graves’ eye disease (Infiltrative Thyroid Ophthalmopathy), different antibodies attack the muscles associated with eye and eyelid movement. Although the thyroid gland and the eye may be under attack by the same immune system, it is felt that both conditions remain independent of one another. The antibodies that attack the eye can cause inflammation and swelling of the muscles around the eye, which is what can eventually cause protrusion of the eyes, double vision and retraction of the eyelids (see above photo’s). In some cases the muscles may be enlarged up to eight times their normal size and may mimic an orbital tumor.
Although the usual tests for thyroid function may be normal in people with Graves’ eye disease, more sophisticated investigations usually reveal some abnormality. The problem is: eye signs may precede, come at the same time or follow hyperthyroidism years later. The treatment and control of hyperthyroidism does not tend to improve the prominent eye appearance or the double vision associated with Graves eye disease. Treatment of the thyroid and or thyroid removal does not always stop the progression of the eye problems. Graves eye disease affects women between the ages of 20 and 45 years.
- Weight Loss
- Tachycardia (rapid heart beat)
- Changes in libido (sex drive)
- Muscle weakness
- Heat intolerance
- Enlarged thyroid gland
- Heart palpitations
- Increased sweating
- Blurred or double vision
- Nervousness & irritability
- Eye complaints, such as redness and swelling
- Hair changes
- Restless sleep
- Erratic behavior
- Increased appetite
- Distracted attention span
- Decrease in menstrual cycle
- Increased frequency of stools
Management must therefore, be individualized and begins with control of the underlying thyroid disease. In the majority of cases, the ophthalmic complications can be managed with local measures only. In approximately 10% of cases further therapy is required, such as anti thyroid drugs, orbital radiotherapy or surgery (see treatment below). The most serious eye complication of hyperthyroidism is a condition called thyroid optic neuropathy which is caused by pressure on the optic nerve causing moderate to severe loss of eyesight. The loss of sight may be subtle, only causing a change in perception of color, to complete loss of eyesight. Treatment should be administered as soon as possible, usually consisting of steroids given by mouth.
If the vision fails to improve then surgery is necessary to relieve the pressure surrounding the optic nerve. The surgery consists of removing the bones in the innermost part of the orbit where the pressure on the nerve is the greatest. This surgery is called an orbital decompression.
The treatment of hyperthyroidism depends very much on the cause of the condition.
For all types of hyperthyroidism, medicines called beta blockers are very helpful. Propranolol (Inderol), metoprolol (Lopressor) and atenolol (Tenormin) are commonly used members of this family of drugs. These drugs do not have any effect on the thyroid gland itself, but do rapidly block the effects of the high hormone levels on the heart, nervous systems and other organs. Therefore, beta blockers help control the heart racing, palpitations, shakes and some of the psychological problems that occur with hyperthyroidism.
For patients who have the “leakage” forms of hyperthyroidism that are due to thyroiditis, a beta blocker is usually the only treatment that is needed, since the hyperthyroidism is only temporary. In the case of viral thyroiditis, sometimes aspirin, or rarely steroids, are needed to control the pain and tenderness in the thyroid gland. In addition, some patients with thyroiditis may temporarily develop an under active thyroid later in the course of their disease and will need therapy with thyroid hormone for a few months.
In the case of an overproduction of thyroid hormone as in Graves’ disease, the hyperthyroid state typically persists for years and additional treatment aimed at slowing down the thyroid gland is necessary. There are three possible types of treatments for doing this: antithyroid drugs, radioiodine and surgery.
- Antithyroid drugs:
Drugs like Propylthiouracil (PTU) or methimazole (Tapazole) decrease the production of thyroid hormone by the thyroid gland. Thyroid hormone levels in the blood usually improve after two weeks of starting these medications and return to normal after six to eight weeks. During this initial stage of treatment, patients are also often treated with beta blockers. For Graves’ disease, medication is usually prescribed for 18 months with frequent follow-up treatments involving blood tests (every two to three months) and the appropriate adjustment of dosage. After 18 months of therapy, approximately 50 percent of Graves’ patients will have gone into remission, which means the drugs can be stopped and the thyroid hormone levels will remain normal. Unfortunately, Graves’ disease will eventually return to many of these patients (approximately 60 percent) and they will need to restart the antithyroid drugs or have radioiodine therapy (see below). For patients with toxic nodules, the antithyroid drugs must be continued long term because the over activity in the nodule will almost always flare up again if the medication is stopped, even for a short period of time.
Most individuals do well on these medications and can continue them long term if they so choose. The most common side effect is a rash, which will require that the medication be stopped if it is severe. Rarer side effects include joint swelling, liver inflammation and a one in 300 chance that the medication will knock down the infection-fighting ability of the immune system. It is thus extremely important that all patients taking antithyroid drugs are aware that they should stop their medication and contact their physician immediately if they develop a fever, sore throat or a bad infection. The physician will then do a white blood cell count on the blood to determine whether it is necessary to stop taking the drug.
PTU and methimazole can be used during pregnancy and by nursing mothers; however, it is important that the physician monitor the woman taking these drugs closely so that the smallest dose possible is prescribed. A pregnant woman’s obstetrician also needs to be aware that she is taking these drugs so that the baby’s thyroid status can be monitored. PTU is the preferred drug for pregnant women since it crosses the placenta and gets into the breast milk less easily than methimazole. Often, Graves’ disease improves as pregnancy progresses, but can flare up again in the postpartum period.
- Radioactive Iodine:
In the United States, radioiodine is a commonly used treatment for Graves’ disease and toxic nodule (s). It has been used effectively for about 50 years. It is safe and does not have any side effects such as an increased risk of cancer or problems with future pregnancy. The treatment consists simply of swallowing a pill that contains radioactive iodine. Usually the treatment is entirely painless, though an occasional patient will notice mild soreness over the thyroid gland for a few days after the treatment. The dose of radioactive iodine that is administered is based upon the radioiodine uptake test described in the making a diagnosis section.
A radioactive iodine treatment takes about two to four months to work, after which most patients actually develop a permanent under active thyroid condition (hypothyroidism). This requires treatment with a once daily natural thyroid hormone supplement. Following a radioactive iodine treatment, your physician will monitor you condition and your blood tests at monthly intervals to be sure that the treatment has been effective and to start the supplement when it is needed. The radioactive iodine treatment is effective about 90 to 95 percent of the time, however an occasional patient may require a second dose.
Radioactive iodine cannot be given to pregnant or nursing women. In addition, patients are asked to take certain precautions after taking a radioactive iodine treatment. Although this advice may sound somewhat frightening, it is just precautionary and designed to minimize the level of exposure of others to radiation. For example, if small children are in the house, patients are asked to avoid kissing them or exposing the child to saliva, because a small amount of the radioiodine is secreted in the saliva. Patients may also be asked to stay perhaps a few yards away from young children for two to three days and to avoid sleeping in the same bed with someone during this period.
Antithyroid drugs may be given before and/or after radioiodine therapy to help control the hyperthyroidism until the radiation has a chance to work. Inorganic iodine may be prescribed after radioiodine to help control thyroid hormone levels.
Surgery is less commonly used as a treatment for hyperthyroidism since most patients can be treated successfully with medications and radioactive iodine. However, surgery may be the best option in certain situations, such as patients with large multinodular goiters where the thyroid gland is compressing the windpipe or interfering with swallowing, or in a pregnant woman who is requiring very high doses of antithyroid drugs such that the baby’s thyroid gland is being affected. Like all operations, removal of the thyroid gland carries the risk of certain complications. These include damage to the nerves that control the vocal cords or to other small glands in the neck that control a person’s calcium level in the blood. In the hands of an experienced thyroid surgeon, the risks of these complications should be only about one to two percent. It is important, however, to find a surgeon who performs this type of operation frequently. As in the case of radioactive iodine therapy, surgery for hyperthyroidism usually leaves the patient with an under active thyroid gland that requires life-long, daily treatment with a thyroid hormone supplement.