Kathryn Jean Lucas, MD |
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Kathryn Jean Lucas, MD |
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| inside health |
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| HYPERTHYROIDISM |
| By: K. Jean Lucas, M.D. |
WHAT IS HYPERTHYROIDISM?
Hyperthyroidism is present when the thyroid is producing too much thyroid hormone. In the early stages of this disorder, a person may have virtually no symptoms but laboratory tests may show a suppressed (below normal) TSH. Thyroid stimulating hormone, as discussed above, is the most sensitive test in diagnosing thyroid disorders.
As the hyperthyroidism becomes more severe, the following symptoms may be present. Not all of these symptoms are necessarily present in individual patients.
Symptoms of Hyperthyroidism:
| Fatigue | Nervousness | Sleep Problems |
| Heat intolerance | Silky hair | Smooth Skin |
| Hair loss | Brittle nails | Anxiety |
| Swelling | Muscle weakness | Palpitations |
| Rapid Heart Rate | Difficulty Swallowing | Eye Irritation |
| Frequent Bowel Movements | Change in Menstrual Periods | |
| Eye Protrusion |
WHY DO PEOPLE BECOME HYPERTHYROID?
A common and easily correctable reason to develop hyperthyroidism is from taking too much thyroid hormone. In this situation, lowering the thyroid hormone dose will alleviate the symptoms within 1-2 weeks. In cases in which spontaneous hyperthyroidism occurs, possible causes include: inflammation of the thyroid (thyroiditis), autoimmune thyroid disease (Hashimoto’s thyroiditis or Graves’ disease), an overactive nodule, or ingestion of excessive iodine containing compounds in a person with an abnormal thyroid. Examples of iodine containing compounds are: IVP dye, contrast used for CT scans, and kelp.
In viral or subacute thyroiditis, the thyroid responds to a viral attack by becoming swollen and painful. The inflammation subsides over several weeks. The inflammation causes the release of thyroid hormone in storage too rapidly. Since thyroid hormone lasts about six weeks, the symptoms of hyperthyroidism usually subside following that length of time. At that point, the thyroid may transiently become underactive until it heals, rebuilds thyroid hormone stores, and resumes normal functioning.
In autoimmune thyroid disease, antibodies attack the thyroid and stimulate it to produce more thyroid hormone. Since the production is increased, this condition does not quickly subside. The thyroid may be larger than normal. Treatment is usually required in order to control the problem. This disorder is inherited and predominates in women. It occurs commonly as women age or after childbirth.
Nodules or lumps in the thyroid may produce excessive amounts of thyroid hormone. The nodules may be multiple as in a multinodular goiter or they may occur as a single area in the thyroid that is over-producing hormone.
Certain medications such as amiodarone may precipitate hyperthyroidism by providing the thyroid with too much iodine. Contrast x-ray media may also produce the same effect in those with an abnormally structured thyroid.
Rarely a pituitary tumor making TSH will stimulate the thyroid to make it produce too much thyroid hormone. In these cases, both the T4 and TSH would be elevated. Surgery would be needed to remove the pituitary tumor.
HOW IS HYPERTHYROIDISM DIAGNOSED?
If your symptoms are suggestive of hyperthyroidism, your physician will order blood tests to confirm the diagnosis. In this condition, the thyroid hormones, T4 and/or T3 are elevated and the TSH is suppressed. To confirm the type of thyroid disease, antibody levels may be done. These antibodies are: TSH receptor antibody (present in Graves’ disease) and antithyroid antibodies (present in Hashimoto’s thyroiditis). A sedimentation rate (a nonspecific measure of inflammation) may be done if viral thyroiditis is suspected. An iodine uptake test may be done to aid the diagnosis. If the uptake is elevated and the thyroid blood tests are high, autoimmune thyroid disease is usually the cause. If the uptake is suppressed, the hyperthyroidism is usually caused by the release of thyroid hormone from an inflamed thyroid gland. Other causes of this type of pattern are: the patient taking too much thyroid hormone, receiving an iodine load from taking supplements containing iodine or contrast during an x-ray, or use of amiodarone, a heart medicine.
HOW IS HYPERTHYROIDISM TREATED?
As with any case of hormone overproduction, the goal of therapy is to correct the initial cause, block the thyroid’s production of hormone, and/or treat the symptoms until the problem resolves on its own.
In viral thyroiditis, anti-inflammatories such as ibuprofen or cortisone may be given to decrease the swelling and pain in the thyroid. Beta-blocker medications such as propranolol, metoprolol, or atenolol may be given to block the rapid heart rate, nervousness, or tremor which may occur. As the thyroid depletes its stores of hormone, thyroid hormone may need to be added temporarily until the gland fully recovers.
In autoimmune thyroid disease, several strategies are used. Antithyroid medication such as propylthiouracil (PTU) or Tapazole will gradually decrease the production of thyroid hormone by the thyroid gland. Radioactive iodine may be given to eventually and permanently destroy the thyroid. Surgery can remove the thyroid, but because the antibodies may be still present in the body, the small amount of thyroid tissue left following surgery may be reactivated.
MEDICATIONS FOR HYPERTHYROIDISM
Beta blockers are a group of drugs which do not correct the underlying thyroid disorder but block the effect of excessive thyroid hormone on the body. These medications will reduce the heart rate to normal and block the nervousness and tremor caused by excessive thyroid hormone. These medications can be used no matter what the cause of the hyperthyroidism.
Antithyroid medications are those which block the production of thyroid hormone by the thyroid. Since viral thyroiditis involves the release of pre-formed thyroid hormone, antithyroid medications will not work in this disorder.
Propylthiouracil (PTU) and Tapazole are given to decrease thyroid hormone levels and stabilize the patient until a therapy can be given that will permanently correct the underlying problem. The drugs are very effective in treating hyperthyroidism, but they do not cure the disease. These medications may have side-effects. Some patients are allergic to them and develop a rash or hives while taking them. PTU may cause an odd taste in the mouth. The white blood cell count may decrease as a result of these medications. Often the count of these infection fighting cells goes back up when the dose is stopped. If you develop an infection (for example, a sore throat, fever, cough) or fever while on these medications, you should always have your WBC count promptly checked by your physician. Another rare side-effect is liver damage, which is also usually corrected by stopping the medication.
To detect side effects from the drugs, it is necessary to closely monitor the blood especially if any of the above symptoms occur. If you develop any of the above symptoms, you need to stop the medication immediately and call your physician that day.
TREATMENT OF HYPERTHYROIDISM
WITH RADIOACTIVE IODINE
Since no treatment exists which will rid the body of the attacking antibodies without affecting the entire immune system, destroying the target of the antibodies is often the only way to cure this disorder. The purpose of the radioactive iodine is to destroy a portion or all of the thyroid gland in order to reduce the amount of thyroid hormone the gland produces to within or below normal levels. This may take weeks or months (or rarely, even years) to occur. Most people with an overactive thyroid gland treated with radioactive iodine eventually develop an underactive thyroid (become hypothyroid).
Most people feel better within several weeks of the radioactive iodine therapy because the iodine also may block the production of the thyroid hormone briefly. However, radioactive iodine treatment may cause an inflammation of the thyroid called radiation thyroiditis, which can present with swelling, tenderness, increased firmness of the thyroid gland and redness of the skin over the gland. If the pain is mild, it may not require treatment or may require mild over-the-counter pain medication such as Tylenol or Advil. If the pain and/or swelling is severe, contact your physician. This inflammation usually resolves spontaneously a few days after the treatment dose is given.
A "thyroid storm", an extremely uncommon problem, is caused by the release of large amounts of thyroid hormone from the thyroid recently treated with radioactive iodine and is characterized by fever, rapid heart rate, intestinal pain or cramping, and tremor may occur. Call your physician if you experience excessive increase in heart rate or fever after the radioactive iodine treatment. You may need to increase your beta-blocker medication if the increase in pulse is bothersome.
All female patients who are capable of becoming pregnant should practice birth control prior to treatment and for six months thereafter. If pregnancy is in question or if recent menstrual periods have been missed, the patient should report this to the doctor prior to treatment. Radioactive iodine is forbidden during pregnancy or breast-feeding.
While a majority of people require only a single radioactive iodine treatment for an overactive thyroid gland, some (less than 5%) may require a repeat treatment to control this condition.
After many long-term studies of patients treated with radioactive iodine, no increased incidence of cancer of any kind has been found to be directly due to the radioactive iodine treatment. In fact, the incidence of thyroid cancer is less in such treated glands, probably because of the destruction of the thyroid tissue.
Radioactive iodine is a safe, effective, and time tested (over 50 years of use) treatment of hyperthyroidism.
PREVENTING WEIGHT GAIN WHILE UNDER TREATMENT
Because of the rapid change in the metabolic rate after you have begun treatment for hyperthyroidism, your weight will have a tendency to increase. However, your appetite should also decrease as the thyroid levels normalize.
To prevent weight gain, you should stick to a low fat diet and eat three meals to a day. Avoid simple sugars which may increase your appetite. If you are hungry in-between meals, then have a small healthy snack. Increasing the fiber content of the diet may satisfy your hunger more and lessen the calories you consume. Check your weight weekly. If you are gaining weight, you should watch your diet even closer, increase your activity further, and discuss any further diet modifications with the dietitian.
When your heart rate has decreased to normal and your muscle weakness has improved, you should start walking, doing low impact aerobics, or beginning other reconditioning exercises after consulting with your physician.
GRAVES EYE DISEASE
Eye problems may be seen in up to 50% of patients with Graves' disease. No other types of hyperthyroidism (such as taking too much thyroid hormone, having an overactive nodule, having an overactive multinodular goiter or developing to a viral thyroiditis) causes eye disease. Most of the time, Graves’ eye disease is very mild; however, in one out of twenty patients, it may progress to a more severe form with potentially disfiguring and sight-threatening effects. This degree of ophthalmopathy is not predictable nor is it preventable; thus Graves' ophthalmopathy is usually treated only when the symptoms become serious or vision is affected.
BACKGROUND
Both Graves' thyroid disease and Graves' eye disease are related autoimmune diseases. Graves' thyroid disease can occur without Graves' eye disease and vice versa. This observation may suggest separate diseases, but in general, there is significant overlap. In fact, one sees a close association in time between the onset of Graves' eye and Graves' thyroid disease, and this suggests a possible common underlying mechanism. The eye symptoms generally occur within 18 months before or after the diagnosis of autoimmune hyperthyroidism.
MECHANISM OF EYE PROBLEMS
As noted above, an autoimmune process is felt to underlie Graves' ophthalmopathy. The antibodies attacking the eye muscles cause an accumulation of substances within the connective tissue and muscles that surround the eyes. Since space in the bony orbit which houses the eyeball is limited, the expansion of the eye muscles and connective tissue can result in forward movement of the eyeball. Protrusion of the eye, at first, serves to relieve pressure behind the eye but eventually this restricts movement of the eye muscles and may cause double vision. With continued pressure, the optic nerve may be affected and vision threatened.
SYMPTOMS OF GRAVES’ EYE DISEASE
Many times the patients with Graves' ophthalmopathy have a gritty, sandy, or burning sensation in their eyes. Associated with this sensation can be blurred vision, increased tearing, and sensitivity to light. With progression of the eye disease, they may feel deep orbital pressure; eyes appear to be "popping" out. The eyes may protrude so far that the lids do not close at night leading to dryness and possible ulcerations of the cornea. Double vision may occur as eye muscles swell and are restricted in their movement. When the eye muscles from both eyes do not move together, the image seen is not clear and may appear to be two. Rarely, involvement of the optic nerve causes decreased vision, dulling of color perception and problems with blind spots or peripheral vision. Smoking is associated with an increased risk of eye disease as well as more severe eye disease.
TREATMENT OF GRAVES EYE DISEASE
As previously mentioned, there is no way to prevent Graves' eye disease nor predict in whom it will be most severe. However, we do know that smokers with Graves’ disease have eye problems more commonly than nonsmokers. The mechanism for this relationship is unknown. Patients with mild eye problems are only treated symptomatically; other therapeutic options such as cortisone treatment and orbital irradiation are used for more severe, sight-threatening disease.
Medical management may include local measures; tinted lenses, ointments and moisturizing eye drops. Patients are advised to avoid smoke-filled rooms, minimize exposure to strong sunlight, not use ceiling fans while sleeping, and avoid wearing contact lenses. Elevating the head of the bed at nighttime may decrease swelling about the eyes. If the eyes are unable to close completely at night, one can use patches or tape to close them. Double vision may be treated by putting prisms in eyeglasses to align the image seen correctly. Use of oral cortisone may be required when vision is threatened or protrusion or inflammation of the eyes is severe. Radiation treatment to the eye muscles is a potential treatment for severe Graves' ophthalmopathy as is surgical decompression of the orbits (removal of part of the bony structure surrounding the eye). Eye muscle surgery is only done after the eye disease has stabilized.
Graves' eye disease requires a coordinated approach including the patient, the endocrinologist and the ophthalmologist. If there is a threat to the patient's eye function, a neuro-ophthalmologist and oculoplastic (eyelid, eye muscle and orbit reconstruction) surgeon may be consulted as well.
After the issue of preservation of vision, the most bothersome symptoms should be addressed. These include both acceptable cosmetic appearance and comfort measures. The patient needs to have full realization that the treatment course may be prolonged. Hopefully, in the future, a better understanding of the disease process will lead to more definitive treatment or prevention of Graves’ eye disease.
"Do Not Take if You Have Thyroid Disease."
Many medications including those for cough and colds will contain a warning on the package, "Do not take this medication if you have thyroid disease." or "Consult your doctor before taking this medication." If your thyroid hormones levels are in the normal range, then you should be able to take any medication that a person without thyroid disease could take. However, if you are too much thyroid hormone or are hyperthyroid, then decongestant medications, medications or beverages with caffeine, and asthma medications, may mimic or increase the symptoms of too much thyroid hormone and cause palpitations, nervousness, and tremor.
FOR FURTHER INFORMATION
NOTES
Copyright 1997-2004 by K. Jean Lucas, M.D. This brochure may not be reproduced without the permission of Dr. Lucas.
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