Hyperthyroidism Symptoms
Don’t ignore hyperthyroidism symptoms. High levels of thyroid hormones from an overactive thyroid can affect multiple organs, from your heart to your eyes.
The butterfly-shaped thyroid gland sitting at the front of your neck is small, but its impact on important bodily functions is huge. Because hormones produced by your thyroid control metabolism, they affect nearly every organ in your body, even how fast your heart beats.
If your thyroid secretes abnormally low amounts of hormones, a condition called hypothyroidism results. Symptoms typically include feeling slowed down, rapid weight gain, and a lower-than-normal body temperature.
But if your thyroid hormone levels are too high (hyperthyroidism), you can experience very different problems — including extreme nervousness, feeling unusually hot, and losing weight rapidly, seemingly for no reason.
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Hyperthyroidism symptoms may take a while to diagnose because they can be confused with anxiety and other health problems. But it’s important to recognize and treat signs of the disease as soon as possible.
Untreated hyperthyroidism can cause serious problems with your heart, bones, muscles, eyes, menstrual cycle, and fertility. During pregnancy, untreated hyperthyroidism can lead to health risks for both the mother and baby.
What causes hypothyroidism symptoms?
While hypothyroidism is more common, hyperthyroidism is not rare. The National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) reports about one in every 100 Americans has the condition, although many don’t know it.
Graves’ Disease, an autoimmune condition, causes more than 70 percent of cases of hyperthyroidism, according to the American Thyroid Association. In Graves’ disease, your immune system produces antibodies that attack your thyroid, causing the gland to increase in size and secrete more thyroid hormones than your body needs.
Another type of hyperthyroidism results when nodules in your thyroid grow, producing excessive thyroid hormones. Inflammation of the thyroid, thyroiditis, can also result in hyperthyroidism and may sometimes be a temporary condition.
Do you have hyperthyroidism symptoms?
Frequent signs and symptoms of hyperthyroidism include:
- Frequent bowel movements or diarrhea
- Fatigue, often extreme
- Feeling overly warm, heat intolerance, and excessive sweating
- Insomnia
- Muscle weakness
- A rapid and sometimes irregular heart rhythm
- Weight loss, which can be drastic
- Shaky hands
Some people with hyperthyroidism also develop Graves' ophthalmopathy, which affects the eyes. More common in smokers, the disorder can cause excessive tearing or dry eyes, protruding eyeballs, red eyes, blurry or double vision, and reduced eye movement.
Signs of hyperthyroidism during pregnancy
Thyroid hormones are critical for the normal development of a baby’s nervous system and brain. The thyroid gland enlarges a bit in healthy women during pregnancy, and it’s normal for pregnancy-related hormones to boost thyroid hormones levels somewhat, according to the NIDDK.
During pregnancy, it’s normal to have some symptoms of hyperthyroidism, such as fatigue, difficulty dealing with heat, and a faster heartbeat. If you have those symptoms and aren’t gaining a normal amount of weight, your doctor will test your thyroid to check your hormone levels.
Mild hyperthyroidism during pregnancy often doesn’t need treatment. More severe hyperthyroidism can lead to miscarriage, premature birth, and even heart failure, but it can be treated with antithyroid medication.
Are you at risk for hyperthyroidism symptoms?
Having relatives with a history of thyroid disease raises your risk for an overactive thyroid. Women are also far more likely to develop hyperthyroidism than men, especially after the age of 60.
Other health problems — including having type 1 diabetes, pernicious anemia, and primary adrenal insufficiency — are linked to an increased risk of hyperthyroidism. You are also more likely to have hyperthyroidism if you take certain medications that contain iodine, such as the drug amiodarone, used to treat serious heart arrhythmias, or if you were pregnant within the past six months.
You can develop hyperthyroidism without any of those risk factors, however. If you have symptoms of an overactive thyroid, talk to your doctor about being tested for hyperthyroidism.
Updated:  
September 27, 2023
Reviewed By:  
Janet O’Dell, RN