Causes

The thyroid gland is an important organ of the endocrine system. It is located in the front of the neck just below the voice box. This gland releases the hormones thyroxine (T4) and triiodothyronine (T3), which control body metabolism. Controlling metabolism is critical for regulating mood, weight, and mental and physical energy levels.

If the body makes too much thyroid hormone, the condition is called hyperthyroidism. (An underactive thyroid leads to hypothyroidism.)

Graves disease is the most common cause of hyperthyroidism. It is caused by an abnormal immune system response that causes the thyroid gland to produce too much thyroid hormones. Graves disease is most common in women over age 20. However, the disorder may occur at any age and may affect men as well.

Symptoms

• Anxiety
• Breast enlargement in men (possible)
• Difficulty concentrating
• Double vision
• Eyeballs that stick out (exophthalmos)
• Eye irritation and tearing
• Fatigue
• Frequent bowel movements
• Goiter (possible)
• Heat intolerance
• Increased appetite
• Increased sweating
• Insomnia
• Menstrual irregularities in women
• Muscle weakness
• Nervousness
• Rapid or irregular heartbeat (palpitations or arrhythmia)
• Restlessness and difficulty sleeping
• Shortness of breath with exertion
• Tremor
• Weight loss (rarely, weight gain)

Exams and Tests

Physical examination shows an increased heart rate. Examination of the neck may show that the thyroid gland is enlarged (goiter).

Other tests include:

• Blood tests to measure levels of TSH, T3, and free T4
• Radioactive iodine uptake

This disease may also affect the following test results:

• Orbit CT scan or ultrasound
• Thyroid stimulating immunoglobulin (TSI)
• Thyroid peroxidase (TPO) antibody
• Anti-TSH receptor antibody

Treatment

The purpose of treatment is to control the overactivity of the thyroid gland. Beta-blockers such as propranolol are often used to treat symptoms of rapid heart rate, sweating, and anxiety until the hyperthyroidism is controlled. Hyperthyroidism is treated with one or more of the following:

• Antithyroid medications
• Radioactive iodine
• Surgery

If you have radiation and surgery, you will need to take replacement thyroid hormones for the rest of your life, because these treatments destroy or remove the gland.

Some of the eye problems related to Graves disease usually improve when hyperthyroidism is treated with medications, radiation, or surgery. Radioactive iodine can sometimes make eye problems worse. Eye problems are worse in people who smoke, even after the hyperthyroidism is cured.

Sometimes prednisone (a steroid medication that suppresses the immune system) is needed to reduce eye irritation and swelling.

You may need to tape your eyes closed at night to prevent drying. Sunglasses and eyedrops may reduce eye irritation. Rarely, surgery or radiation therapy (different from radioactive iodine) may be needed to return the eyes to their normal position.

Outlook (Prognosis)

Graves disease often responds well to treatment. However, thyroid surgery or radioactive iodine usually will cause hypothyroidism. Without getting the correct dose of thyroid hormone replacement, hypothyroidism can lead to:

• Depression
• Mental and physical sluggishness
• Weight gain

Antithyroid medications can also have serious side effects.

Possible Complications

• Complications from surgery, including:
  • Hoarseness from damage to the nerve leading to the voice box
  • Low calcium levels from damage to the parathyroid glands (located near the thyroid gland)
  • Scarring of the neck
• Eye problems (called Graves ophthalmopathy or exophthalmos)
• Heart-related complications, including:
  • Rapid heart rate
  • Congestive heart failure (especially in the elderly)
  • Atrial fibrillation
• Thyroid crisis (thyrotoxic storm), a severe worsening of overactive thyroid gland symptoms
• Increased risk for osteoporosis, if hyperthyroidism is present for a long time
• Complications related to thyroid hormone replacement
  • If too little hormone is given, fatigue, weight gain, high cholesterol, depression, physical sluggishness, and other symptoms of hypothyroidism can occur
  • If too much hormone is given, symptoms of hyperthyroidism will return

When to Contact a Medical Professional

Call your health care provider if you have symptoms of Graves disease. Also call if your eye problems or general symptoms get worse (or do not improve) with treatment.

Go to the emergency room or call the local emergency number (such as 911) if you have symptoms of hyperthyroidism with:

• Decrease in consciousness
• Fever
• Rapid, irregular heartbeat

Alternative Names

Diffuse thyrotoxic goiter

References

AACE Thyroid Task Force. American Association of Clinical Endocrinologists medical guidelines for clinical practice fo rthe evaluation and treatment of hyperthyroidism and hypothyroidism. Endocr Pract. 2002;8(6).

Davies TF, Larsen PR. Thyrotoxicosis. In: Kronenberg HM, Melmed S, Polonsky KS, Larsen PR, eds. Williams Textbook of Endocrinology. 11th ed. Philadelphia, Pa: Saunders Elsevier; 2008:chap 11.

Ladenson P, Kim M. Thyroid. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 244.

Update Date: 4/20/2012

Reviewed by: Ari S. Eckman, MD, Division of Endocrinology and Metabolism, Johns Hopkins School of Medicine, Baltimore, MD. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.