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Signs and Symptoms of an Underactive Thyroid

It’s possible to have an underactive thyroid and not experience any symptoms. Many people with hypothyroidism don’t even realize they have it until their doctor diagnoses it

design things shows thyroid and diagnosis

If you have an underactive thyroid, also known as hypothyroidism, it can cause a range of symptoms or none at all. Some people don’t realize they have it because they attribute the subtle symptoms to aging or stress.

The symptoms most people associate with an underactive thyroid are weight gain and tiredness. But there are lesser-known signs and symptoms of hypothyroidism that you should know about, so you can get the correct diagnosis and treatment sooner rather than later.

Feeling cold all the time

If you always feel cold, it could be a sign of an underactive thyroid. A lack of heat generation in the body is among the classic signs and symptoms of hypothyroidism. You may notice it’s hard to warm up when you’re cold or that your hands and feet are always freezing. People with hypothyroidism often feel cold even in a warm environment, and fatigue may accompany those chilly sensations, along with depression and weight gain.

Brain fog and forgetfulness

Although many things can cause brain fog and forgetfulness, an underactive thyroid is a relatively common cause that’s easily overlooked. Individuals with hypothyroidism often feel overwhelmed and unable to concentrate on tasks due to mental fog and fatigue.

If you have an underactive thyroid gland, you may find it hard to concentrate or have difficulty completing tasks due to a lack of motivation. Other health conditions, such as nutritional deficiencies, can cause brain fog and forgetfulness. But if you’re forgetting things or have problems concentrating, it’s a sign that you should see your healthcare provider for a check-up.


One of the most common signs of an underactive thyroid is constipation. This can happen for reasons other than hypothyroidism, including:

• Lack of adequate fiber in your diet

• Not drinking enough water

• Lack of exercise (if you don’t move around, your body

can’t work properly!)

• Medications (including antidepressants) that alter

bowel movements. Although these drugs are meant

to help with anxiety or depression, they can have side

effects such as constipation.

• A blockage in the colon.

However, hypothyroidism can also cause constipation. It’s something to consider if you’ve ruled out other causes.

Dry, itchy skin

Dry, itchy skin is a common sign of an underactive thyroid. However, many other conditions can cause dry skin, including stress, low humidity, taking too many hot baths, and poor nutrition. If you suddenly notice your skin is dry and itchy and you have other symptoms suggestive of an underactive thyroid, see your doctor for testing. You might also notice that your nails become brittle and dull as your thyroid function declines since they depend on adequate oil production in the skin.

Hair loss

Hair loss from hypothyroidism is typically diffuse and affects the entire scalp rather than a specific area. You might also notice that you see more scalp than usual due to hair loss. There are other reasons for hair loss but having this symptom is a sign you should get your thyroid tested.

Mood changes

One of the most common signs of hypothyroidism is mood changes. These could include feeling “down” or depressed, having difficulty concentrating or making decisions, and feeling extremely exhausted or sluggish. As thyroid function decreases, you may find it difficult to cope with everyday tasks, even those once easy to manage. You might feel down or sad for no apparent reason.

It is important to note that these symptoms do not always indicate hypothyroidism and could also be caused by other factors. If you have any of these symptoms, you must speak to a healthcare professional to determine the cause.

You could have no symptoms as all

It’s possible to have an underactive thyroid and not experience any symptoms. Many people with hypothyroidism don’t even realize they have it until their doctor diagnoses them via a blood test. That’s why it’s smart to get thyroid blood testing every year and sooner if you have symptoms of hypothyroidism. Most doctors will want to rule out other causes of symptoms before diagnosing you with a thyroid condition such as hypothyroidism.

Diagnosing hypothyroidism

Doctors diagnose hypothyroidism with physical examinations, medical histories, and laboratory tests. Laboratory tests, such as a TSH test, can measure the level of thyroid hormones in the body. The TSH level is typically elevated in patients with hypothyroidism.

Your doctor may also test free thyroxine (FT4) and triiodothyronine (T3) levels, which are typically reduced in patients with hypothyroidism. Depending on the symptoms and medical history, your doctor may also recommend imaging tests, such as a thyroid ultrasound or an iodine uptake scan.


Some of these symptoms may not seem life-threatening. But if you have them, talk to your doctor about the possibility of an underactive thyroid. If they diagnose you with this condition, treatments are available that can help.


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