Written by
Louise W Lu, PhD, MPH, BMLS
Written/Reviewed by
Alexandra V Goldberg, Registered Dietitian
Three months ago, Ms Lin was almost certain she had an anxiety disorder.
Her heart was racing, her hands were shaking, and her sleep was awful – every symptom seemed to fit. The psychiatrist told her:
“Get more sunlight, exercise regularly, and your mood will gradually improve.”
But strangely, whenever she went out in the daytime, she felt dizzy almost immediately and her heart started pounding even faster. Within five minutes she would have to sit down and rest. Exercise made her feel short of breath and panicky, nothing like the “you’ll feel more relaxed after moving” that everyone talks about.
After a month of taking the medication and doing exactly what she was told – more sun, more exercise – her “anxiety” not only failed to improve, she actually felt more heat-intolerant and her sleep got even worse.
During a health consultation, the registered dietitians at the LOLU Health team suggested she have her thyroid function tested.
When the results came back, she was stunned: everything she had thought was “just an emotional problem” turned out to be caused by hyperthyroidism – excess thyroid hormones keeping her body in a constant state of overdrive.
Reminder: this is educational information and does not replace an in-person consultation and diagnosis with your doctor.
1｜Why Does “Anxiety” So Often Mask Hyperthyroidism?
Many people, when they first experience a racing heart, chest tightness, trembling hands, or poor sleep, naturally assume they are “just too stressed.”
In the clinic, doctors hearing these symptoms often prioritize anxiety or panic-like conditions.
But the issue is—the symptoms of hyperthyroidism can look almost identical to anxiety.
When thyroid hormones are elevated, the body behaves as if the accelerator pedal has been pushed to the floor: the heart beats faster, body temperature rises, the mind becomes tense and overstimulated, and sleep becomes light and easily disrupted.
On the surface, these reactions look exactly like a nervous system overstimulated by anxiety, making them very difficult to distinguish based on sensations alone.
The real reason misdiagnosis is so common is that the two issues originate from different systems:
- Anxiety stems from heightened activity in the nervous system;
- Hyperthyroidism comes from metabolic overactivation.
Yet the lived experience is strikingly similar: sudden heart racing, trembling, restlessness, heat intolerance, and shallow, easily disrupted sleep.
Even more importantly, hyperthyroidism increases the body’s sensitivity to adrenaline, meaning your body becomes far more likely to produce “anxiety-like reactions”—even when there is no emotional trigger.
This also explains why someone like Ms Lin feels dizzy and experiences a rapid heartbeat as soon as she steps into sunlight.
For individuals with hyperthyroidism, the body is already overheated and running fast. When exposed to additional heat—such as direct sunlight—the risk of dizziness, palpitations, and chest discomfort increases significantly.
These symptoms are not psychological at all, but signals that the body is already operating beyond what it can handle.
Another important factor: women are 5–10 times more likely than men to develop thyroid disorders.
Yet in clinical encounters, women’s symptoms are more often attributed to “stress,” “emotional sensitivity,” or “hormonal fluctuations,” especially when the presentation is subtle or accompanied by insomnia or mood changes.
In such cases, a condition rooted in the endocrine system can easily be mistaken for anxiety.
Sometimes, it’s simply your body sending a different message: your thyroid function (TSH, T3, T4) may need to be tested.
2｜Which Signs Suggest You Might Have Missed Hyperthyroidism?
When anxiety and hyperthyroidism look so similar on the surface, the key question becomes:
Are there any details that are not very common in anxiety, but are quite typical in hyperthyroidism?
These details are often the crucial clues that help you decide whether it’s time to check your thyroid.
The following signs do not need to appear all at once, but if you notice several of them in yourself,
it’s worth becoming more alert to the possibility of thyroid dysfunction.
| Presentation | Explanation / Why It Suggests Hyperthyroidism |
|---|---|
|
Heat intolerance, easy sweating (even after light activity) |
Anxiety usually causes sweaty palms, but doesn’t make your whole body feel “overheated all the time.” With hyperthyroidism, temperature regulation is impaired, so you feel hotter and sweat more than people around you. |
| Hand tremor (fine shaking) | Hyperthyroidism makes the body more sensitive to adrenaline, so minor tremors become more obvious, especially when you extend your hands. |
| Unexplained weight loss | Your appetite is normal or even better than usual, yet your weight keeps dropping—because your metabolic rate has been “forced into high gear,” and your body is burning more energy without you noticing. |
| Waking frequently at night, shallow sleep |
With anxiety, the main problem is often “difficulty falling asleep.” With hyperthyroidism, it is more common to “finally fall asleep, only to be woken in the middle of the night by heat, a racing heart, or a restless body” — a shallow sleep pattern driven by abnormal metabolism. |
| Elevated resting heart rate |
Even when you are not stressed and not exercising, your heart rate stays higher than normal
(for example 85–110 beats per minute), suggesting that your body is “idling in fast mode.” |
| Increased bowel movements |
Going to the bathroom two or three times a day or more, with stool still fairly formed and not like typical diarrhea, is very common in hyperthyroidism, because gut motility has also been “dragged along and sped up.” |
| Neck swelling or a sensation of something stuck |
Feeling that the middle of your neck is a bit swollen or tight, or wanting to clear your throat more often, may indicate changes in the size or structure of the thyroid. |
| Shorter menstrual cycles or lighter periods (in women) |
Thyroid hormones influence sex hormones and pituitary signals, which can shorten the menstrual cycle and reduce flow. This is a classic endocrine red flag, but is often blamed on “stress” or “poor sleep.” |
Why Are Women More Likely to Be Missed?
From epidemiological data, women are about 5–10 times more likely than men to develop thyroid disease.
This risk is especially pronounced in several key phases—such as postpartum, perimenopause, and periods of long-term
high stress and poor sleep—when the immune and endocrine systems are more easily “pushed” out of balance.
At the same time, in clinical conversations, women’s symptoms are more easily attributed to “stress,” “emotional issues,”
or “hormonal changes.”
When symptoms are not very typical, or are accompanied by insomnia and mood swings, thyroid problems are more likely
to be overlooked.
and you visit a doctor with “anxiety-like symptoms,” you are more likely to be treated as having a psychological issue first, rather than an endocrine one.
A Simple Self-Check: Should You Test Your Thyroid?
This short checklist is not a diagnostic tool, but it can help you decide whether you should talk to your doctor about running a thyroid function panel (TSH, T3, T4):
- ✅ You have been receiving treatment for anxiety or mood symptoms for > 1–3 months with almost no improvement.
- ✅ You feel particularly unwell, dizzy, or notice a racing heart when you are in the sun or in hot environments.
- ✅ You have clear heat intolerance, excessive sweating, a rapid heartbeat, or hand tremors.
- ✅ Your sleep is getting lighter, and you often wake at night due to heat, a pounding heart, or vague bodily discomfort.
- ✅ Your appetite is normal or even better than before, but your weight is gradually going down.
- ✅ (For women) Your menstrual cycles are shorter and your flow has decreased, yet it keeps being dismissed as “stress” or “just age.”
If you tick two or three of these boxes, it is very worthwhile to mention to your doctor at your next visit:
“Could we also check my thyroid function?”
This step is often the key to distinguishing between “anxiety that never gets better” and “hyperthyroidism that has
simply been missed.”
3｜How Can You Confirm It? Which Tests Should You Ask For (Diagnosis)
When the symptoms of anxiety and hyperthyroidism overlap, the most reliable way to tell them apart is not by guessing or “going by feel,” but by——
doing a simple blood test.
1) The Three Essential Tests: TSH, FT4, FT3
① TSH (Thyroid-Stimulating Hormone) – the Most Sensitive “First Gate”
TSH is the first indicator doctors look at to judge whether the thyroid is functioning normally.
In most cases of hyperthyroidism, TSH drops significantly, sometimes to almost undetectable levels.
The reason is simple: when thyroid hormone levels in the body are already too high, the brain tries to “hit the brakes”
by reducing the secretion of TSH, in an attempt to stop the thyroid from releasing even more hormone.
So, the lower the TSH, the more likely it is that the thyroid is overly “revved up.”
② FT4 (Free Thyroxine) and FT3 (Free Triiodothyronine)
These two tests measure the thyroid hormones in your blood that are actually “biologically active.”
In typical hyperthyroidism, their levels are often above the normal range:
- Very low TSH + elevated FT4 → strongly suggests hyperthyroidism
- Very low TSH + clearly elevated FT3 → may also indicate a more active hyperthyroid state
In simple terms: TSH is like the “commander,” and FT4/FT3 are the “soldiers on the front line.”
If the commander is shouting “stop,” but the soldiers are still charging forward, it means the system is out of balance.
2) Additional Tests to Identify the Cause (Highly Recommended)
Hyperthyroidism can have different causes, such as Graves’ disease or autoimmune thyroiditis.
Different causes may require different treatments and have different prognoses. The following two tests help your doctor
understand “where the hyperthyroidism is coming from”:
③ TRAb (TSH Receptor Antibodies)
TRAb is mainly used to determine whether you have Graves’ disease, the most common type of hyperthyroidism.
If TRAb is significantly elevated, it often suggests that the immune system is “attacking” the thyroid by mistake.
People in this situation may also experience eye symptoms such as eye pressure, dryness, or a slight bulging sensation.
④ TPOAb (Thyroid Peroxidase Antibodies)
TPOAb reflects whether there is an autoimmune response targeting the thyroid.
If it is clearly elevated, it suggests that the thyroid has come under the “watch” of the immune system,
and it can help determine whether there is an immune-related thyroid condition (for example, Hashimoto’s thyroiditis
with a hyperthyroid phase).
3) Imaging: Thyroid Ultrasound (Strongly Recommended as a Complement)
On top of blood tests, a thyroid ultrasound can provide very important structural information:
- Is the thyroid enlarged?
- Is the tissue uniform, or are there many small “speckled” areas?
- Is blood flow significantly increased on Doppler (suggesting a “high-activity” thyroid)?
- Are there any suspicious nodules that need follow-up or further assessment?
Ultrasound has no radiation and is very quick. Combined with TSH, FT4, FT3, and antibody tests,
it helps your doctor build a much more complete picture of your thyroid health.
4) How Can You Talk to Your Doctor?
Many patients feel shy about bringing this up, but in reality, you have every right to ask for a more complete
evaluation of your health.
You can express your concerns and needs like this:
I’ve also tried treating it as anxiety, but the results haven’t been very good.
I’m worried there might be a thyroid problem behind this.
Could you please help me add tests for TSH, FT4, FT3, thyroid antibodies, and a thyroid ultrasound if needed?”
5) Why Is ‘Wait and See’ Not Enough—and Why Testing Matters
Choosing to “wait and see” only makes sense if the problem is likely to resolve on its own.
But for hyperthyroidism, that is usually not the case:
- Undiagnosed hyperthyroidism over the long term may increase the risk of arrhythmias (such as atrial fibrillation).
- Persistently elevated metabolism can gradually wear down your heart, bones, and overall energy.
- Sleep, weight, mood, and concentration can all be slowly dragged down by this constant “overdrive.”
Most importantly, you can only find truly effective solutions once you’ve found the real cause.
Once hyperthyroidism is properly diagnosed and managed, many seemingly “emotional” symptoms often improve much faster
than you’d expect.
