What Is Hyperthyroidism?

Your heart keeps racing at rest. You're eating normally — maybe more than usual — yet the scales keep drifting down, and you feel hot and restless when everyone else is comfortable. What's going on? One answer clinicians check for is an overactive thyroid. The video above, "Hyperthyroidism," runs for about seven and a half minutes and centres on the most common cause, Graves' disease, explaining how an immune-system mix-up can push the thyroid into overdrive. This page walks through the questions people usually ask next.

Isn't this just the opposite of an underactive thyroid?

In a sense, yes. Your thyroid, the small gland at the front of your neck, makes hormone that sets the pace at which your body uses energy. Too little hormone and everything slows — that's hypothyroidism, covered in our companion guide to what hypothyroidism is and how it is treated. Too much hormone, and the pace rises instead. That's hyperthyroidism: the gland is overactive, and the body's systems run faster than they should.

So why would a thyroid suddenly speed up?

The anchor video puts Graves' disease at the centre of the story, and for good reason — it's a common cause. Graves' is an autoimmune disorder: as the video explains, an autoimmune disorder occurs when the immune system mistakenly attacks healthy tissue, and in this case that misdirected activity drives the gland to produce too much hormone. It isn't the only route to an overactive thyroid — inflammation of the gland or growths within it can also push hormone levels up — which is why finding the cause matters, not just spotting that the level is high.

What does it actually feel like?

Think of a body idling too fast. People commonly describe a pounding or racing heartbeat, feeling shaky or restless, and finding heat hard to tolerate. Weight can fall even though appetite is good, energy can feel wired rather than refreshed, and sleep can suffer. Some people notice the gland itself swelling at the front of the neck. None of these signs on its own proves a thyroid problem — anxiety, infection, and plenty of other conditions can mimic parts of the picture — so the feeling is a reason to get checked, not a diagnosis in itself.

How will the clinician sort it out?

Blood tests come first: they measure the thyroid hormone level and the signals that control the gland, and together they show whether it's genuinely overactive. The appointment usually includes a hands-on neck examination, too — the site's video "Examination of the Thyroid - Clinical Examination" shows how that works, with the examiner standing in front of the seated patient to inspect and feel the gland in the front of the neck. Depending on what those first steps suggest, your team may look further for the underlying cause, such as Graves' disease, before settling on a plan.

And how is it calmed down?

Treatment aims to bring hormone production back into line and to settle the symptoms while that happens. Broadly, the options include medicines that reduce how much hormone the gland makes, treatments that reduce the gland's activity more permanently, and — in some situations — surgery to remove part or all of it. Which route fits depends on the cause, the severity, and your own circumstances, so it's a decision made with your clinician after the test results are in, not one an article can make for you. What matters most is not sitting on a racing heart: book the appointment, get the blood test, and let the numbers speak.

Frequently Asked Questions

What is the difference between hyperthyroidism and hypothyroidism?

Direction. Hyperthyroidism means the thyroid makes too much hormone and the body speeds up; hypothyroidism means it makes too little and the body slows down. The blood tests and treatments are different, which is why confirming which one you have matters.

What is Graves' disease?

An autoimmune disorder in which the immune system mistakenly attacks healthy tissue and drives the thyroid to overproduce hormone, as the anchor video on this page explains. It is a common cause of hyperthyroidism, but not the only one.

Can hyperthyroidism go away on its own?

Some causes settle and others persist, and only follow-up blood tests can show which is happening in your case. Don't wait it out with a racing heart — get tested, and let your own team judge the pattern over time.

How long is the anchor video?

About seven and a half minutes (7 minutes 31 seconds by the video file itself). It explains that Graves' disease is an autoimmune disorder leading to an overactive thyroid gland, and what an autoimmune disorder means.

MedicalVideos.com has published trusted medical videos since 2007. The site was founded by Dr. Mohamed Ibrahim, MD, PhD — physician-scientist.

Educational only — this article is general information about hyperthyroidism, not medical advice and not a diagnosis. A racing heartbeat, unexplained weight loss, and other symptoms described here should be assessed promptly in person by your clinician.