Over-active thyroid, also referred to as hyperthyroidism, is a condition where the thyroid gland in the body produces too much thyroxine (hormone that regulates many of the bodily functions, growth and metabolism, and is responsible for energy production from individual cells), resulting in specific symptoms that require management. It is a condition opposite to HYPOthyroidism, where, as the name suggests, the thyroid gland produces insufficient thyroxine.
There are several causes of hyperthyroidism, the most common of which is Graves disease, a condition where the body’s immune system targets its own thyroid gland, resulting in over production of thyroxine.
Occasionally a viral infection can affect the thyroid gland and cause inflammation within the thyroid called a thyroiditis where the gland can become painful and sore to touch. Thyroiditis is associated with transient over-activity which can last for a few weeks before the thyroid function swings and becomes underactive (hypothyroidism) before finally it returns to normal thyroid function. Thyroiditis is sometimes also seen after delivery of a baby called post-partum thyroiditis.
Iodine contained in the food you eat is used by your thyroid gland to produce the thyroid hormones thyroxine and triiodothyronine. However, taking additional iodine in supplements can cause your thyroid gland to produce too much thyroxine or triiodothyronine.
The type of overactive thyroid that can result from this is known as iodine-induced hyperthyroidism, sometimes referred to as Jod-Basedow phenomenon. It usually only occurs if you already have non-toxic nodules in your thyroid gland.
SIGNS AND SYMPTOMS
Hyperthyroidism can mimic other health problems, which may make it difficult for your doctor to diagnose. It can also cause a wide variety of signs and symptoms, including:
- Sudden weight loss, even when your appetite and the amount and type of food you eat remain the same or even increase
- Rapid heartbeat (tachycardia) — commonly more than 100 beats a minute — irregular heartbeat (arrhythmia) or pounding of your heart (palpitations)
- Increased appetite
- Nervousness, anxiety and irritability
- Tremor — usually a fine trembling in your hands and fingers
- Changes in menstrual patterns
- Increased sensitivity to heat
- Changes in bowel patterns, especially more frequent bowel movements
- An enlarged thyroid gland (goiter), which may appear as a swelling at the base of your neck
- Fatigue, muscle weakness
- Difficulty sleeping
- Skin thinning
- Fine, brittle hair
Sometimes an uncommon problem called Graves’ ophthalmopathy may affect your eyes, especially if you smoke. In this disorder, your eyeballs protrude beyond their normal protective orbits when the tissues and muscles behind your eyes swell. This pushes the eyeballs forward so far that they actually bulge out of their orbits. This can cause the front surface of your eyeballs to become very dry. Eye problems often improve without treatment.
Signs and symptoms of Graves’ ophthalmopathy include:
- Protruding eyeballs
- Red or swollen eyes
- Excessive tearing or discomfort in one or both eyes
- Light sensitivity, blurry or double vision, inflammation, or reduced eye movement
DIAGNOSIS AND MANAGEMENT
Diagnosis of hyperthyroidism is made after evaluation of symptoms and thyroid function test, where thyroxine levels, as well as TSH are measured. Normally in patients with hyperthyroidism, Thyroxine levels are higher than normal, while TSH levels are low.
Several treatments for hyperthyroidism exist. The best approach for you depends on your age, physical condition, the underlying cause of the hyperthyroidism, personal preference and the severity of your disorder:
Radioactive iodine. Taken by mouth, radioactive iodine is absorbed by your thyroid gland, where it causes the gland to shrink and symptoms to subside, usually within three to six months. Because this treatment causes thyroid activity to slow considerably, causing the thyroid gland to be underactive (hypothyroidism), you may eventually need to take medication every day to replace thyroxine.
Anti-thyroid medications. These medications gradually reduce symptoms of hyperthyroidism by preventing your thyroid gland from producing excess amounts of hormones. They include propylthiouracil and methimazole. Symptoms usually begin to improve in 6 to 12 weeks, but treatment with anti-thyroid medications typically continues at least a year and often longer. Both drugs can cause serious liver damage, sometimes leading to death. Because propylthiouracil has caused far more cases of liver damage, it generally should be used only when you can’t tolerate methimazole.
Beta blockers. These drugs are commonly used to treat high blood pressure. They won’t reduce your thyroid levels, but they can reduce a rapid heart rate and help prevent palpitations. For that reason, your doctor may prescribe them to help you feel better until your thyroid levels are closer to normal. Side effects may include fatigue, headache, upset stomach, constipation, diarrhea or dizziness.
Surgery (thyroidectomy). If you’re pregnant or otherwise can’t tolerate anti-thyroid drugs and don’t want to or can’t have radioactive iodine therapy, you may be a candidate for thyroid surgery, although this is an option in only a few cases.