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Hormones & Aging

Overactive Thyroid: 7 Symptoms to Check, and Why It Gets Missed After 60

An overactive thyroid speeds almost everything up. After 60 it often shows up quietly instead, and gets filed as depression or ageing.

Ageless Coach Editorial Team · September 12, 2026

In 30 Seconds
About 1 in 100 adults has it. NIDDK says about 1 out of 100 Americans ages 12 years and older have hyperthyroidism, and that it is more common in women and in people older than 60. NIDDK
After 60 it can look like depression. NIDDK says that in older adults, hyperthyroidism is sometimes mistaken for depression or dementia, and that symptoms may instead be loss of appetite or withdrawal from people. NIDDK
One blood panel settles it. Cleveland Clinic says blood tests check thyroid hormone levels, and that in hyperthyroidism T3 and T4 sit above normal while TSH is often lower than normal. Cleveland Clinic

An overactive thyroid has seven common symptoms, and after 60 the loudest of them is usually the heart.

The thyroid is a small gland at the base of the neck. It sets the pace for the rest of the body. When it makes too much hormone, almost everything runs fast: the heart, the gut, the sweat glands, the nerves.

Below are the seven symptoms worth checking, then the reason this gets missed in older adults, and the one blood test that ends the guessing.

1
The Symptoms · 7

Seven signs the gland is running too fast

Cleveland Clinic says hyperthyroidism happens when the thyroid makes and releases too much thyroid hormone. The symptoms can start suddenly. They can also develop slowly over time.

Slowly is the harder version. These seven are the ones people notice.

  1. A heart that races or skips. Cleveland Clinic lists rapid heart rate and heart palpitations first, and Mayo Clinic names a fast heartbeat, an irregular heartbeat and a pounding heart. NIDDK says an untreated irregular heartbeat can lead to stroke and heart failure.
  2. Weight falling while appetite rises. Mayo Clinic says losing weight without trying is a symptom, alongside increased hunger. Cleveland Clinic explains why: the condition speeds up the metabolic rate, so the body burns more calories than usual.
  3. Hands that will not stay still. Mayo Clinic describes a tremor, usually a small trembling in the hands and fingers. Cleveland Clinic calls it shakiness, like hand tremors, and lists it alongside muscle weakness.
  4. Heat that nobody else feels. Mayo Clinic names sweating and increased sensitivity to heat. Cleveland Clinic adds warm, moist skin, which is one of the things a provider checks for during the physical exam.
  5. Sleep that will not come. Cleveland Clinic lists difficulty sleeping, and Mayo Clinic pairs sleep issues with nervousness, anxiety and irritability. NIDDK groups those with fatigue.
  6. The gut speeds up too. Mayo Clinic names changes in bowel patterns, especially more frequent bowel movements. Cleveland Clinic lists diarrhea or more frequent pooping, and NIDDK lists frequent bowel movements.
  7. A swelling at the base of the neck. All three sources name it. Mayo Clinic calls an enlarged thyroid gland a goiter, which may appear as a swelling at the base of the neck. NIDDK calls it an enlargement in the neck.
1 in 100
NIDDK says about 1 out of 100 Americans ages 12 years and older have hyperthyroidism, and that it is more common in women and in people older than 60.
Source: NIDDK

Any one of the seven has other explanations. Three together is a reason to ask for a thyroid panel.

2
After 60

Why the same illness looks different in older adults

Mayo Clinic says older adults are more likely to have symptoms that are hard to notice. It names an irregular heartbeat, weight loss, depression, and feeling weak or tired during ordinary activities.

That list is the problem. Every item on it is what a busy clinic expects from someone over 60 for other reasons.

A gloved hand drawing blood from the inside of a person's arm with a fine needle
Cleveland Clinic says thyroid blood tests check T3, T4 and TSH levels.

NIDDK puts it plainly. In older adults, hyperthyroidism is sometimes mistaken for depression or dementia. Older adults may show different symptoms, such as loss of appetite or withdrawal from people.

NIDDK also says overactive thyroid nodules are found most often in older adults. So the group most likely to have this is the group whose symptoms read least clearly.

In older adults, hyperthyroidism is sometimes mistaken for depression or dementia.

NIDDK

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3
The Test

What the blood test shows, and what caused it

NIDDK says a diagnosis cannot be based on symptoms alone. Too many of them match other diseases. Doctors use thyroid blood tests and imaging tests to confirm it and find the cause.

Cleveland Clinic describes the numbers. In hyperthyroidism, T3 and T4 sit above normal. TSH is often, though not always, lower than normal. A thyroid antibody test can show whether Graves' disease is behind it.

A clinician wearing gloves holding a patient's wrist to take a pulse
Mayo Clinic names a fast or irregular heartbeat among the symptoms, and among the serious complications.
3 causes
Mayo Clinic names Graves' disease, overactive thyroid nodules and thyroiditis as the conditions that lead to hyperthyroidism, and says Graves' disease is the most common of the three.
Source: Mayo Clinic

NIDDK adds two causes from the medicine cabinet rather than the gland. Taking too much thyroid hormone medicine is one. NIDDK says anyone on that medicine should have their levels checked at least once a year.

Too much iodine is the other. NIDDK names kelp, dulse and other seaweed. It says some cough syrups and heart medicines contain a lot of iodine. Cleveland Clinic names amiodarone and iodine contrast dye.

✗
Sorted

Three things people believe about an overactive thyroid

Three ideas send people down the wrong road, and each has a clear answer.

An overactive thyroid makes you gain weight. The opposite is closer to true. Cleveland Clinic says it does not typically cause weight gain. Some people lose weight even with an increased appetite, because the metabolic rate speeds up. Weight gain points at an underactive thyroid instead.

Diet can fix it. Cleveland Clinic says diet changes alone often cannot fix hyperthyroidism. You will likely need medical treatment. Iodine matters in one direction only. NIDDK says large amounts of seaweed, or iodine supplements, may cause or worsen it.

It is a minor problem if you feel fine. Untreated, it is not. NIDDK lists an irregular heartbeat that can lead to blood clots, stroke and heart failure. It adds thinning bones and osteoporosis. Cleveland Clinic adds atrial fibrillation and congestive heart failure.

📋Your Coach's Recommendations
1
Count your pulse for a week at rest.
Mayo Clinic names a fast or irregular heartbeat among the symptoms and among the serious complications. Sit still two minutes, count for thirty seconds and double it. Seven mornings of numbers is a real receipt to hand over.
2
Bring every pill and supplement you take.
NIDDK says too much thyroid hormone medicine and too much iodine can both cause hyperthyroidism, and names seaweed supplements, cough syrups and certain heart medicines. Cleveland Clinic names amiodarone. Take the containers, not a memory of them.
3
Ask for a thyroid panel by name.
NIDDK says a diagnosis cannot be based on symptoms alone. Cleveland Clinic says blood tests check T3, T4 and TSH. If you are over 60 and have been told this is low mood or ageing, ask whether the thyroid has been tested.

To your health,

Ageless Coach

Age Strong. Live Long.

Trusted Sources Behind This Article
Cleveland ClinicMayo ClinicNIDDK

This article is education, not medical advice. Cleveland Clinic says signs of thyroid storm, such as a high fever and a very fast heart rate, mean getting to the nearest hospital as soon as possible. Mayo Clinic says to make an appointment for unintended weight loss, a rapid heartbeat or swelling at the base of the neck.

Frequently Asked Questions

How do I know if it is my thyroid or just stress?
You cannot tell from symptoms alone. NIDDK says a diagnosis cannot be based on symptoms, because many of them match other diseases. Cleveland Clinic says blood tests check T3, T4 and TSH.
Is this the same as an underactive thyroid?
No, they are opposites. Cleveland Clinic says hyperthyroidism speeds up metabolism and often causes weight loss, while hypothyroidism slows it and may lead to weight gain. Same gland, reversed direction.
What happens if I leave it alone?
NIDDK says untreated hyperthyroidism can cause an irregular heartbeat that leads to blood clots, stroke and heart failure, an eye disease called Graves' ophthalmopathy, and thinning bones.
Can I still eat fish and use salt?
Ask before you change anything. Cleveland Clinic says too many iodine rich foods may cause or worsen hyperthyroidism in some cases, and lists fish, seaweed, shellfish, dairy, egg yolks and iodized salt among the foods a low iodine diet avoids. It says to consult a provider or dietitian first.
Does it ever settle by itself?
Sometimes, depending on the cause. Mayo Clinic says that in some cases it may improve without medicines or other treatment. NIDDK says thyroiditis can cause a temporary overactive phase that later turns underactive.
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