Hypothyroidism: Symptoms, Causes, and Treatments

What is hypothyroidism?

Hypothyroidism is a condition where you have a lower-than-normal amount of thyroid hormones in your blood. Your body needs these hormones to keep everything running smoothly. Thyroid hormones help to regulate your body temperature, control how your body uses energy, and keep your organs working well. 

There are three key hormones that play a role in hypothyroidism:

• Thyroid stimulating hormone (TSH): This is a hormone made by the pituitary gland in your brain. It travels to the thyroid gland and tells it to produce thyroid hormones. If you have plenty of thyroid hormones in your blood, the pituitary gland shuts off TSH production. TSH can be low or high in hypothyroidism. In most cases, though, it’s high.

• Thyroxine (T4): This is a hormone made by the thyroid gland. In hypothyroidism, T4 levels are low. 

• Triiodothyronine (T3): This is also a hormone made by the thyroid gland. T3 levels are low in hypothyroidism. About 80% of the T3 in your body is made from T4. 

Thyroid hormones are made in your thyroid, a butterfly-shaped gland in your neck. When your thyroid gland isn’t working well — or has been destroyed or removed — it doesn’t make enough thyroid hormones to keep up with your body’s demands.

What’s the Difference Between Hypothyroidism and Hyperthyroidism?

Written by Mandy Armitage, MD

What causes hypothyroidism?

Hypothyroidism can be caused by many different things:

• Autoimmune disease: This is the most common cause of hypothyroidism. In some cases, the immune system attacks and damages the thyroid gland. This can happen suddenly or slowly over many years. Examples of autoimmune thyroid disease are Hashimoto’s thyroiditis and atrophic thyroiditis. 

• Surgery: Some people may have all or part of their thyroid gland removed because of thyroid nodules, thyroid cancer, or Graves’ disease. 

• Radiation treatment: Some people may need to have their thyroid gland destroyed with radiation. Other people who have radiation therapy for another reason — like for a cancer in the head or neck — can also end up with radiation damage to their thyroid. 

• Congenital hypothyroidism (birth defect): Some babies are born with only a partial thyroid gland, no thyroid gland at all, or a thyroid gland in a different place (called an ectopic thyroid). 

• Thyroid inflammation (thyroiditis): A viral infection or autoimmune attack can cause inflammation in your thyroid gland. This can sometimes cause your thyroid to stop working well.

• Medication: Some medications can get in the way of your thyroid gland working normally. Examples are amiodarone and lithium. 

• Iodine imbalance: Your body needs iodine, an essential mineral, to make thyroid hormones. Too much or too little iodine can make hypothyroidism worse.

• Pituitary gland damage: The pituitary gland in your brain makes TSH, a messenger that tells your thyroid when to make hormones. If the pituitary gland is damaged, your thyroid gland may not make enough hormones. 

• Rare disorders: Other health conditions, such as sarcoidosis or amyloidosis, can make the body deposit certain substances in the thyroid. This can get in the way of making thyroid hormones.

What Causes Hypothyroidism? Common Reasons for a Low or Underactive Thyroid

Written by Farah Naz Khan, MD

What are the symptoms of hypothyroidism?

Some people with hypothyroidism have no symptoms. Other people can have mild, moderate, or even severe symptoms. 

Symptoms can include:

• Fatigue

• Weight gain

• Feeling cold when others aren’t (cold intolerance)

• Dry skin

• Brittle nails

• Hair loss

• Constipation

• Depression

• Muscle aches

• Joint pain

• Poor concentration or memory

• Irregular periods

• Enlarged thyroid gland (goiter)

It’s important to note that these symptoms aren’t specific to thyroid disease. For example, symptoms like fatigue, weight gain, and dry skin can all be caused by other health conditions too. This can make diagnosis challenging in some cases.

Hypothyroidism in Women: 10 Signs and Symptoms to Know

Written by Maria Robinson, MD, MBA

How hypothyroidism is diagnosed

If you have symptoms that aren’t explained by something else, consider talking to a healthcare professional about your thyroid function. It can be helpful to also discuss your medical history and family history. 

A laboratory test (or tests) to measure your TSH, T3, and T4 is essential. A TSH level is usually the first lab test recommended. 

Here are some possible outcomes of your thyroid lab tests:

• Normal TSH: Your thyroid function is probably normal. If you have a lot of symptoms, a healthcare professional might still check your T4 just to be safe. 

• Slightly high TSH, normal T4: You may have borderline or subclinical hypothyroidism. This can be an early, mild thyroid problem, or it can be due to stress or illness. Medication is sometimes used for people who have hypothyroid symptoms or who are hoping to get pregnant. But, in many cases, subclinical hypothyroidism is temporary and goes away on its own. 

• High TSH, low T4: You may have primary hypothyroidism. This means your pituitary gland is healthy — and making plenty of TSH — but your thyroid isn’t responding. Most people with primary hypothyroidism will need to take medication. 

• Low TSH, low T4: You may have secondary (or central) hypothyroidism. This means that both your pituitary and thyroid glands are having trouble making hormones. Most people with secondary hypothyroidism will also need to take medication. 

• Low TSH, high T4: You may have hyperthyroidism (an overactive thyroid).

Should You Get Tested for Hypothyroidism?

Written by Nicole Rowe, MD

Medications for hypothyroidism

Most types of hypothyroidism are treated by replacing the missing thyroid hormones. This brings your thyroid hormone levels back to normal and allows your body’s organ systems to work well again. Most people feel completely normal on thyroid replacement medication. 

Levothyroxine (synthetic T4)

Levothyroxine (synthetic, or lab made, T4) is the gold standard when it comes to treating hypothyroidism. Levothyroxine is a thyroid hormone replacement. It acts just like the T4 made by your own thyroid gland. 

Levothyroxine is only available by prescription. There are many FDA-approved brand name versions of levothyroxine, including:

• Unithroid 

• Levoxyl

• Synthroid

Liothyronine (synthetic T3)

Liothyronine is another type of lab-made thyroid hormone: T3. This medication replaces the hormone normally made by your body. It’s also FDA approved for hypothyroidism. 

Liothyronine is only available by prescription. A popular brand name is Cytomel.

For most patients, liothyronine isn’t usually recommended. In the past, liothyronine was sometimes used as add-on medication to treat lingering symptoms. But studies have shown that taking T3 and T4 together doesn’t really seem to have an advantage over taking T4 on its own. 

Desiccated thyroid (animal T3/T4)

This is an older medication made from dried, powdered animal thyroid glands (like pigs, cows, or sheep). Unlike levothyroxine, it isn’t approved or regulated by the FDA, and it naturally contains both T4 and T3. 

Desiccated thyroid is only available by prescription. Brand name examples include Armour Thyroid and Nature-Throid. 

Overall, desiccated thyroid isn’t used commonly. When compared to levothyroxine, desiccated thyroid hasn’t been studied as well. And the amount of hormones in each dose can also vary widely.

Is Synthroid or Cytomel Better for Hypothyroidism?

Written by Emilie White, PharmD

Diet and lifestyle treatments for hypothyroidism

Up to 45% of people believe that alternative medicine can help hypothyroidism. However, there just isn’t a lot of good evidence to support these claims. 

Vitamins and yoga

Though vitamins, supplements, and coconut oil may have other health benefits, they don’t treat hypothyroidism. There may be some potential benefits to yoga and certain herbs, but research is ongoing. 

Diet

There’s no specific diet that’s helpful for treating hypothyroidism. In general, eating a balanced diet with lots of fruits, vegetables, and fiber can be good for your overall health. 

Iodine

Though it’s true that iodine deficiency can cause hypothyroidism, this is actually very rare in the U.S. Most people get plenty of iodine through foods and salt. And beware: Taking too much iodine can actually make hypothyroidism worse.

The Truth About Natural Treatments for Hypothyroidism

Written by Ana Gascon