Your thyroid is a small gland in your throat, located just below your voice box (larynx). Your thyroid has a vital role in regulating nearly every bodily function. For example, it makes hormones necessary for a healthy metabolism.
(Metabolism is the rate at which your body processes and breaks down chemicals—for example, changing food to energy).
If you have an overactive thyroid, your thyroid creates too many hormones. Excess hormones cause many processes to accelerate. As a result, you may experience a higher resting heart rate or digest your food faster than usual. An overactive thyroid can also impact your fertility and cause you to feel tired, anxious, or irritable.
There are numerous possible symptoms, so this article will help you learn to spot the signs of an overactive thyroid (hyperthyroidism).
If you suspect you have an overactive thyroid, a healthcare professional can screen for hyperthyroidism via a blood test. Testing usually involves measuring thyroxine (T4), triiodothyronine (T3), and thyroid-stimulating hormone (TSH) levels.
If your blood levels indicate that you’ve developed an overactive thyroid, keep in mind that’s is a common and treatable condition. The American Thyroid Association reports that more than 12% of the US population will develop a thyroid condition during their lifetime.¹ Research indicates that you may have an elevated risk of developing an overactive thyroid if you are:
Over the age of 60
Have been pregnant recently²
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There are a few signs of an overactive thyroid which might be misleading at first. The symptoms may seem like a good thing (initially). Easy to overlook signs include:
Unexpected weight loss With an undiagnosed overactive thyroid, you may notice you’re losing weight — yet you haven’t made any significant changes to your exercise or eating habits. As a result, your appetite may also increase.
Extra energy Hyperactivity is an early sign of an overactive thyroid. However, when left untreated, hyperthyroidism will eventually make you feel fatigued because your metabolism is in overdrive.
Recognizable symptoms Some of the more apparent symptoms of an overactive thyroid (hyperthyroidism) include:
Goiter (swollen thyroid gland)
Increased heart rate or palpitations
Weakness and poor muscle tone
Intolerance to heat
Hair breaking or thinning
More frequent bowel movements
Shorter menstrual cycle in females
Bulging eyes and vision changes (attributed to Graves’ disease)
An estimated 80% of people³ with an overactive thyroid have Graves' disease. Graves’ disease is an autoimmune condition that triggers the immune to attack the thyroid, causing it to produce excess thyroid hormone.
Non-cancerous lumps can form in your thyroid, changing levels of thyroxine (T4) and triiodothyronine (T3) and causing hyperthyroidism.
Thyroiditis An inflamed thyroid isn’t always painful or even noticeable, but it can cause an overactive thyroid. Thyroiditis may arise from taking certain medications. An estimated 5–10% of pregnant women will develop inflammation of the thyroid⁴ after giving birth. Excessive iodine Consuming too much iodine — a mineral necessary for producing thyroid hormone — can make you develop an overactive thyroid. Typically, excess iodine intake is due to dietary iodine (food or supplements). Seafood and seaweed (kelp) are exceptionally high in iodine. Certain medications contain iodine. Be sure to speak with your doctor about any concerns regarding medication or supplements.
How is an overactive thyroid diagnosed?
Your doctor will usually begin evaluating your thyroid health by running blood tests to analyze your hormone levels. You may also be referred to a specialist called an endocrinologist for help identifying the underlying cause of your overactive thyroid.
There are several ways to treat an overactive thyroid. Your doctor will determine the most suitable course of treatment based on your hyperthyroidism severity and cause. Treatment options usually include anti-thyroid medication, radioactive iodine therapy, or, in some cases, surgical removal of the thyroid (either partial or complete removal).
If you experience any of the above symptoms, speak to a qualified healthcare professional. It’s particularly important to seek medical attention and get your thyroid function tested if you’re experiencing changes to your heart rate, blood pressure, or breathing. Additional reasons to get evaluated by a doctor include feeling extremely irritable, anxious, or experiencing bouts of vomiting or diarrhea.
Your thyroid has an essential role in regulating your bodily functions. An overactive thyroid can cause various symptoms impacting your heart, hair, skin, digestion, menstruation, mood, muscle tone, and vision. A variety of treatment options exist that can help you manage an overactive thyroid, usually beginning with non-invasive options, such as medication. In more severe cases, surgery may be necessary.
General information/Press room | American Thyroid Association
Graves' Disease | NIDDK
Postpartum thyroiditis | American Thyroid Association