Diseases

Hyperthyroidism can be suspected in patients with

• tremors,
• excessive sweating,
• smooth velvety skin,
• fine hair,
• a rapid heart rate, and
• an enlarged thyroid gland.

There may be puffiness around the eyes and a characteristic stare due to the elevation of the upper eyelids. Advanced symptoms are easily detected, but early symptoms, especially in the elderly, may be quite inconspicuous. In all cases, a blood test is needed to confirm the diagnosis. The blood levels of thyroid hormones can be measured directly and usually are elevated with hyperthyroidism. However, the main tool for detection of hyperthyroidism is measurement of the blood TSH level. As mentioned earlier, TSH is secreted by the pituitary gland. If an excess amount of thyroid hormone is present, TSH is "down-regulated" and the level of TSH falls in an attempt to reduce production of thyroid hormone. Thus, the measurement of TSH should result in low or undetectable levels in cases of hyperthyroidism. However, there is one exception. If the excessive amount of thyroid hormone is due to a TSH-secreting pituitary tumor, then the levels of TSH will be abnormally high. This uncommon disease is known as "secondary hyperthyroidism." Although the blood tests mentioned previously can confirm the presence of excessive thyroid hormone, they do not point to a specific cause. If there is obvious involvement of the eyes, a diagnosis of Graves' disease is almost certain. A combination of antibody screening (for Graves' disease) and a thyroid scan using radioactively-labelled iodine (which concentrates in the thyroid gland) can help diagnose the underlying thyroid disease. These investigations are chosen on a case-by-case basis.

The options for treating hyperthyroidism include:

• Treating the symptoms
• Antithyroid drugs
• Radioactive iodine
• Surgery treating symptoms

Functioning adenoma and toxic multinodular goiter The thyroid gland (like many other areas of the body) becomes lumpier as we get older. In the majority of cases, these lumps do not produce thyroid hormones and require no treatment. Occasionally, a nodule may become "autonomous," which means that it does not respond to pituitary regulation and produces thyroid hormones independently. This becomes more likely if the nodule is larger than 3 cm. When there is a single nodule that is independently producing thyroid hormones, it is called a functioning nodule. If there is more than one functioning nodule, the term toxic, multinodular goiter is used. Functioning nodules may be readily detected with a thyroid scan. Excessive intake of thyroid hormones Taking too much thyroid hormone medication is actually quite common. Excessive doses of thyroid hormones frequently go undetected due to the lack of follow-up of patients taking their thyroid medicine. Other persons may be abusing the drug in an attempt to achieve other goals such as weight loss. These patients can be identified by having a low uptake of radioactively-labelled iodine (radioiodine) on a thyroid scan. Abnormal secretion of TSH A tumor in the pituitary gland may produce an abnormally high secretion of TSH (the thyroid stimulating hormone produced by the pituitary gland). This leads to excessive signaling to the thyroid gland to produce thyroid hormones. This condition is very rare and can be associated with other abnormalities of the pituitary gland. To identify this disorder, an endocrinologist performs elaborate tests to assess the release of TSH. Excessive iodine intake The thyroid gland uses iodine to make thyroid hormones. An excess of iodine may cause hyperthyroidism. Iodine-induced hyperthyroidism is usually seen in patients who already have an underlying abnormal thyroid gland. Certain medications, such as amiodarone (Cordarone), which is used in the treatment of heart problems, contain a large amount of iodine and may be associated with thyroid function abnormalities.

Hyperthyroidism due to any cause is suggested by several signs and symptoms; however, patients with mild disease usually experience no symptoms. In patients older than 70 years, the typical signs and symptoms also may be absent. In general, the symptoms become more obvious as the degree of hyperthyroidism increases. The symptoms usually are related to an increase in the metabolic rate of the body. Common symptoms include:

• Excessive sweating
• Heat intolerance
• Increased bowel movements
• Tremor (usually fine shaking)
• Nervousness, agitation, anxiety
• Rapid heart rate, palpitations, irregular heart rate
• Weight loss
• Fatigue, weakness
• Decreased concentration
• Irregular and scant menstrual flow
• Fine or brittle hair
• Thinning skin
• Sleep disturbances

In older patients, irregular heart rhythms and heart failure can occur. In its most severe form, untreated hyperthyroidism may result in "thyroid storm," a condition involving high blood pressure, fever, and heart failure. Mental changes, such as confusion and delirium, also may result.

Some common causes of hyperthyroidism include:

• Graves' Disease
• Functioning adenoma and toxic multinodular goiter (TMNG)
• Excessive intake of thyroid hormones
• Abnormal secretion of TSH
• Thyroiditis (inflammation of the thyroid gland)
• Excessive iodine intake

Graves' disease, which is caused by a generalized overactivity of the thyroid gland, is the most common cause of hyperthyroidism. In this condition, the thyroid gland usually is renegade, which means it has lost the ability to respond to the normal control by the pituitary gland via TSH. Graves' disease is hereditary and is up to five times more common among women than men. Graves' disease is thought to be an autoimmune disease, and antibodies that are characteristic of the illness may be found in the blood. These antibodies include thyroid stimulating immunoglobulin (TSI antibodies), thyroid peroxidase antibodies (TPO), and TSH receptor antibodies. What are the symptoms of Graves' disease? In addition to the symptoms of hyperthyroidism mentioned above, Grave's disease may be associated with eye disease (Graves' ophthalmopathy) and skin lesions (dermopathy). Ophthalmopathy can occur before, after, or at the same time as the hyperthyroidism. Early on, it may cause sensitivity to light and a feeling of "sand in the eyes." The eyes may be reddened and produce excess tears. Swelling behind the eyeballs causes the eyes to protrude, and double vision can occur. The degree of ophthalmopathy is worsened in those who smoke.The course of the eye disease is often independent of the thyroid disease, and steroid medications may be necessary to control the inflammation that causes the ophthalmopathy. In addition, surgical intervention may be required. The skin condition (dermopathy) is rare and causes a painless, red, lumpy skin rash on the front of the legs. What are the triggers for Graves' disease? The triggers for Graves' disease include:

• stress,
• smoking,
• radiation to the neck,
• medications, and
• infectious organisms such as viruses.

Graves' disease can be diagnosed by a standard, nuclear medicine thyroid scan which shows diffusely increased uptake of a radioactively-labelled iodine. In addition, a blood test may reveal elevated TSI levels.

Hyperthyroidism is a condition in which an overactive thyroid gland is producing an excessive amount of thyroid hormones that circulate in the blood. ("Hyper" means "over" in Greek). Thyroid hormones include thyroxine (T4) and triiodothyronine (T3), representing 99.9% and 0.1% of thyroid hormones, respectively. T3 is actually the most active thyroid hormone. Much of the T4 is converted to T3 in the bloodstream. The thyroid itself is regulated by the pituitary gland in the brain. The pituitary is further regulated by another gland in the brain, the hypothalamus. The hypothalamus releases a hormone called thyrotropin releasing hormone (TRH), which sends a signal to the pituitary gland to release thyroid stimulating hormone (TSH). In turn, TSH sends a signal to the thyroid to release thyroid hormones. With overactivity of any of these three glands, an excessive amount of thyroid hormones can be produced, thereby resulting in hyperthyroidism Thyrotoxicosis is a toxic condition that is caused by an excess of thyroid hormones from any cause. Thyrotoxicosis can be caused by an excessive intake of thyroid hormone or by overproduction of thyroid hormones by the thyroid gland. Because both health-care professionals and patients often use these words interchangeably, we will take some liberty by using the term "hyperthyroidism" throughout this article. Thyroid Gland illustration - Hyperthyroidism

Inflammation of the thyroid gland may occur after a viral illness (subacute thyroiditis). This condition is association with a fever and a sore throat that is often painful on swallowing. The thyroid gland is also tender to touch. There may be generalized neck aches and pains. Inflammation of the gland with an accumulation of white blood cells known as lymphocytes (lymphocytic thyroiditis) may also occur. In both of these conditions, the inflammation leaves the thyroid gland "leaky," so that the amount of thyroid hormone entering the blood is increased. Lymphocytic thyroiditis is most common after a pregnancy and can actually occur in up to 8% of women after delivery. In these cases, the hyperthyroid phase can last from 4 to 12 weeks and is often followed by a hypothyroid (low thyroid output) phase that can last for up to 6 months. The majority of affected women return to a state of normal thyroid function. Thyroiditis can be diagnosed by a thyroid scan.

If you are concerned that you may have an excess amount of thyroid hormone, you should mention your symptoms to your doctor. A simple blood test is the first step in the diagnosis. From there, both you and your doctor can decide what the next step should be. If treatment is warranted, it is important for you to let your doctor know of any concerns or questions you have about the options available. Remember that thyroid disease is very common, and in good hands, the diseases that cause an excess of thyroid hormones can be easily diagnosed and treated.

Endocrinologists are specialists in diagnosing and treating hormonal disorders such as hyperthyroidism. Primary care physicians, including family practitioners and internists, may also be involved in treating patients with hyperthyroidism. Ophthalmologists and ophthalmic surgeons may be involved in the care of patients with Graves' disease.