Thyrotoxicosis

Thyrotoxicosis means an excess of thyroid hormone in the body. Having this condition also means that you have a low level of thyroid stimulating hormone, TSH, in your bloodstream, because the pituitary gland senses that you have “enough” thyroid hormone. If you are thyrotoxic, you may feel nervous or irritable, because all of your body’s functions are speeding up.

Hyperthyroidism, also referred to as an overactive thyroid is the most common cause of thyrotoxicosis and, occurs when your thyroid gland produces too much thyroid hormone.

The most common cause of hyperthyroidism is Graves' Disease, in which the immune system, for reasons that are not clearly understood, releases antibodies that attack or “bind” to thyroid cells. The process stimulates the thyroid gland, causing it to grow and produce high levels of thyroid hormone. As many as 70-80% of patients with hyperthyroidism have Graves’ disease and it may run in families.

Graves' Disease is also referred to as diffuse toxic goiter because it affects the entire thyroid gland (diffuse), causes people with the condition to appear flushed (toxic) and the gland becomes enlarged (goiter).

People who have an autoimmune disease, such as Graves’ disease, are at higher risk of developing other autoimmune diseases, such as type 1 diabetes or Addison’s disease.

A single nodule or multiple nodules in the thyroid gland which can produce excessive thyroid hormone also can cause hyperthyroidism.

Thyrotoxicosis can also come from inflammation of the gland (thyroiditis ) or from taking too much thyroid medication. In these cases the thyroid gland itself is not overactive, but there is still too much thyroid hormone in the blood. Untreated, thyrotoxicosis can lead to serious medical complications such as heart rhythm disturbances and Osteoporosis, caused from the long-term effects of hormone overproduction.

Another condition, called subclinical hyperthyroidism, may be diagnosed when you have low levels of thyroid stimulating hormone (TSH) but normal levels of thyroid hormone. Your doctor may treat asymptomatic (without symptoms) subclinical hyperthyroidism to avoid future symptoms.


Signs and Symptoms
Mild thyrotoxicosis may not cause any symptoms to begin with. Symptoms associated with more severe cases include:

  • Nervousness
  • Irritability
  • Fatigue
  • Fast heartbeat
  • Weight loss
  • Insomnia
  • Hair loss
  • Thin skin
  • Intolerance to heat
  • Increased perspiration
  • Muscle aches
  • Weakness in upper arms and thighs
  • Increased bowel movements
  • Decreased menstrual flow
  • Eye irritation or inflammation; “bulging” eyes

Treatment
Treatment for thyrotoxicosis will depend upon your age, the cause and severity of your illness, and other medical conditions you may have. Untreated thyrotoxicosis can lead to serious medical complications such as heart rhythm disturbances and osteoporosis caused from the long-term effects of hormone overproduction.

Drug treatment
Two “antithyroid” drugs are available to treat hyperthyroidism. These drugs inhibit the thyroid gland’s production of thyroid hormone. Drugs used for this purpose include methimazole (Tapazole) and propylthiouracil (PTU).

Another class of drugs called beta adrenergic blocking agents can diminish some of the symptoms of thyrotoxicosis. The level of thyroid hormone in your blood, however, is not affected, so you will continue to have high levels of this hormone circulating in your bloodstream. These drugs include propranolol (Inderal), atenolol (Tenormin), metoprolol (Lopressor) and nadolol (Corgard). They are usually used in combination with other treatment for thyrotoxicosis.

Radioactive iodine
Your doctor may choose to treat your condition by permanently damaging the cells in the thyroid that produce thyroid hormone. This can be accomplished with the use of radioactive iodine, which has been utilized as a treatment regimen since the 1940s. Radioactive iodine is a tasteless and odorless substance that is swallowed in capsule or liquid form. Once ingested, it is absorbed into the bloodstream and is taken up by the overactive thyroid cells. Over a period of several weeks your thyroid gland will shrink in size and blood levels of thyroid hormone and thyroid stimulating hormone (TSH) will return to normal. A second radioactive iodine treatment may be needed to achieve desired results.

Most patients who have had radioactive iodine therapy eventually become hypothyroid because their thyroid gland is not producing enough thyroid hormone. This condition is treated with daily intake of thyroid hormone replacement therapy.

Surgery
Your doctor may recommend that you have surgery to remove all or part of your thyroid gland. You may be a candidate for partial removal of your thyroid gland if one or more nodules on the gland are overactive. However, if many nodules are involved or if your entire thyroid gland is overactive, your doctor may suggest that most or all of it be removed. The upside to this type of treatment is that your hyperthyroid condition – and the severe complications that can arise from it – will be greatly reduced. Surgery for hyperthyroidism is indicated in only a limited number of patients. Your doctor will talk to you about the pros and cons of this treatment and whether or not it is the best option for you.

Surgery to remove part or all of your thyroid gland is done under a general anesthetic in the operating room. Your doctor will make a thin incision along the front of your neck, usually along a natural crease in your skin. He/she will then remove the affected part of your gland. Surgery to remove one lobe of your thyroid is called a lobectomy. Sometimes the central portion (isthmus) that connects the two lobes is also removed (isthmusectomy). Surgery to remove most of your gland is called a subtotal thyroidectomy. Surgery to remove your entire gland is called a total thyroidectomy. In some instances, your doctor will determine how much of the gland to remove during surgery.

The total time for your operation is about 1 ½ hours.

You may experience a sore throat and hoarseness for several weeks after your operation, which is normal with this type of surgery. Once the majority of your gland is removed, you will need to take thyroid hormone replacement therapy every day to replace the hormone that is not being made naturally in your body. Your doctor will also talk to you about regular check-ups and blood tests to help monitor your condition.