What Happens If You Leave Hypothyroidism Untreated?

If you have hypothyroidism, you’re not alone. In fact, about 5 out of every 100 people in this country have it. 

Fortunately, it’s easy to correct for most people. But leaving hypothyroidism untreated can cause trouble. That’s because your thyroid gland affects almost every one of your bodily functions. 

When your thyroid gland is underactive, it can be tough to put the signs together to recognize the issue. And without treatment, an underactive thyroid can cause serious mental and physical health problems. 

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What is hypothyroidism, and what causes it?

Hypothyroidism is when the thyroid does not make enough thyroid hormone to meet the body’s needs. While it can affect anyone (including children), people over the age of 60 are at especially high risk. Other important risk factors are listed below.

Medications

Certain medications can affect your thyroid hormone levels. Some common ones are:

• Lithium

• Amiodarone (Pacerone)

• Bexarotene (Targretin)

• Birth control pills/hormone replacement therapy

• Antidepressants (like sertraline)

• Anti-seizure medicines (like carbamazepine , phenytoin, phenobarbital)

Thyroid surgery

A thyroidectomy is a procedure where you have all or part of your thyroid removed. In some cases, you may still have thyroid tissue in place after thyroid surgery. But, what’s left might not be able to make enough hormones for your body.

A history of hyperthyroidism

Hyperthyroidism is an overactive thyroid. It can have just as many health consequences as an underactive thyroid, and needs treatment as well. 

Previous treatment for too much thyroid hormone can leave you without enough. Also, an overactive thyroid can burn itself out over time and have a hard time producing thyroid hormone.

Radiation to areas around the thyroid

Radiation for treatment of head and neck cancers can damage the thyroid gland as a side effect. The same radiation beams that kill the cancer cells can also damage the body’s normal tissues. This can lead to your thyroid gland functioning poorly, resulting in hypothyroidism.

Family history of hypothyroidism

Hypothyroidism tends to run in families. You have a higher chance of developing  hypothyroidism if your family members have it — specifically close family members like parents, grandparents, or siblings.

Pregnancy 

The hormonal changes during pregnancy can cause changes to the thyroid gland. But you can also develop autoimmune thyroid issues after pregnancy. An autoimmune disease is when your immune system attacks your body. In this case, your immune system attacks your thyroid gland.Postpartum thyroiditis is an autoimmune condition much like Hashimoto’s thyroiditis. It can occur up to one year after pregnancy.

An autoimmune condition

Having one autoimmune disease increases your chances of getting others. Autoimmune diseases include conditions like: 

• Type 1 diabetes

• Rheumatoid arthritis

• Celiac disease

• Alopecia areata (hair loss)

• Vitiligo (loss of skin color)

• Pernicious anemia (decrease in red blood cells). 

Iodine deficiency

Without iodine, the thyroid gland can’t make thyroid hormone. This is now mostly an issue in developing countries and not in the U.S. In the U.S., iodine is added to salt and other foods to prevent deficiency.

What are some common signs of hypothyroidism?

This is the tricky part. It’s easy to attribute the signs of hypothyroidism to something else: stress, aging, not enough sleep, not drinking enough water. Typically, the effects creep up on you over months to years. Here’s what to look out for:

• Low energy level, even when you get enough sleep

• Weight gain, even when you are not overeating

• Skin, hair, and nail changes (dry skin, hair loss, and brittle nails)

• Irregular periods

• Irritability

• Feeling cold when others don’t

• Forgetfulness 

• Tingling or prickling sensations in your hands, arms, legs, or feet

• Swelling and puffiness

• Cramps

• Constipation

• Decreased libido

Listen to your body. Report your symptoms to your primary care provider. They will take your history, examine you, and decide if you need testing.

How is hypothyroidism diagnosed?

Hypothyroidism is diagnosed with a blood test. Most commonly, your provider will check your level of thyroid stimulating hormone (TSH) as a screening tool. A high TSH level means there is not enough thyroid hormone in your blood, and the brain is sending signals to the thyroid to make more. Depending on the results, your doctor might order another blood test to check a full thyroid panel or test for autoimmunity. 

In most labs, the normal range for TSH is 0.4 mU/L to 4.0 mU/L. A TSH higher than 4.0 mU/L could mean hypothyroidism. TSH levels between 5.0 mU/L and 10.0 mU/L, are considered a mild TSH elevation. 

Most providers agree that TSH levels of 10.0 mU/L or greater are highly elevated and warrant treatment. Dangerously high TSH levels cause you to have a greater risk of heart disease. In rare cases, a very high TSH level can lead to myxedema coma — a potentially fatal condition in people with longstanding untreated hypothyroidism.

What happens if you don’t treat hypothyroidism?

Untreated hypothyroidism can lead to serious mental and physical health problems. Complications of untreated hypothyroidism can include the following.

Mental health changes

Hypothyroidism affects your mind as well as your body. It can slow your thoughts, make you forgetful, and affect your ability to concentrate. In fact, hypothyroidism is one of the reversible causes of dementia. 

Not having enough thyroid hormone puts a damper on your emotional well-being, too. You could experience more mood swings and irritability. People with hypothyroidism might be more likely to have anxiety and depression. If you already suffer from depression, being hypothyroid can make it harder to treat. 

Goiter

An underactive thyroid might become enlarged (goiter). Goiters are usually painless lumps in the front of your neck. They can cause you to cough, make your voice hoarse, and affect your breathing and swallowing. If the goiter is small and doesn’t cause symptoms, it may not need to be treated. Treatment, if necessary, usually consists of medication or surgery.

Heart disease

Having an underactive thyroid can increase your risk of heart disease. It can have a direct effect on the heart, making it beat slower and less efficiently. And it also has an effect on the coronary arteries, affecting proper blood flow. This raises the risk of coronary artery disease and congestive heart failure. If you have heart disease already, hypothyroidism can make it worse.

Nerve damage

Long-term hypothyroidism can damage nerves. You might feel symptoms like:

• Pain

• Numbness

• Tingling

• Weakness, most commonly in the hands 

The nerves of the hand travel through a narrow channel in the wrist called the carpal tunnel. Carpal tunnel syndrome can result from hypothyroidism causing inflammatory changes in the tunnel. This can hurt the nerves inside. 

Nerve damage from untreated hypothyroidism can also cause hearing loss.

Is untreated hypothyroidism life-threatening?

If severe hypothyroidism isn’t treated for a long time, it can be life-threatening. Myxedema coma can happen when the body systems slow down so much that you’re left in a coma. Even with treatment, many people do not survive. 

The good news is it is easy to detect and treat hypothyroidism, so getting to this point is very rare.

How does untreated hypothyroidism affect fertility and pregnancy? 

Hypothyroidism can affect your fertility and make it harder to get pregnant. It can make your period irregular, which means you won’t be able to track ovulation. Or it can prevent you from ovulating altogether. In one study, almost 25% of women with infertility had hypothyroidism. After treatment, most were able to conceive (become pregnant) within 6 weeks to 1 year. 

During pregnancy, insufficient thyroid hormone can be dangerous for both the mother and the baby. And there is a higher risk of miscarriage. You may also be at risk of other pregnancy complications like: 

• High blood pressure

• Anemia

• Bleeding (hemorrhage)

• Placental abruption (early separation) 

Higher levels of thyroid hormones are needed to meet the demands of pregnancy. Without treatment, hypothyroidism can affect the baby’s development. There might be a higher risk of complications, like: 

• Preterm birth

• Low birth weight

• Respiratory distress

• Stillbirth

In addition, studies have found that the IQ scores of children born to hypothyroid mothers can be lower than those born to mothers with normal thyroid hormone levels. 

While this may sound scary, the risks to moms and babies are avoidable with the right treatment. 

Is there hypothyroidism screening in pregnancy?

Screening for hypothyroidism during pregnancy is a little controversial. But most experts agree that testing for hypothyroidism isn’t for everyone in pregnancy. The two groups that should get checked include:

• Those with risk factors (like thyroid antibodies, autoimmune disease, prior infertility)

• Those with symptoms — so make sure to keep your healthcare provider in the loop

If you fall into one of these categories, see your provider as soon as you find out you’re pregnant. Even better, talk about these issues while you are still in the planning stages. 

Levothyroxine is safe to take in pregnancy. If you already take it, there is a good chance you will need a higher dose to meet the demands of your growing baby. Your provider will watch your thyroid levels throughout your pregnancy and after delivery. They will adjust your levothyroxine dose if necessary.

How is hypothyroidism treated?

Hypothyroidism is not curable, but it is totally correctable. 

Synthetic thyroxine is recommended for hypothyroidism. It mimics the hormones released by your thyroid gland. The most common synthetic thyroxine medication used to treat hypothyroidism is levothyroxine (L-thyroxine, Synthroid, Levoxyl, Levothroid, Tirosint, and Unithroid). 

The dose depends on factors like:

• Thyroid hormone level

• Age

• Weight

• Medical history

• Gender

Your provider will estimate your starting dose and watch your thyroid hormone levels. They will make adjustments if they need to. 

How do you know if you’re on the right dose of thyroid medication?

Your provider will regularly monitor your thyroid hormone levels after you start medication. Finding the perfect dose for you may involve a bit of trial and error. If your levels reveal that your TSH is still too high, your provider will likely raise your dose. If your TSH is too low, your provider will probably lower your dose. 

Symptoms can also be a clue that your medication needs an adjustment. If your thyroid medication is too low, you’ll have symptoms of hypothyroidism. Signs your thyroid medication is too low can include:

• Feeling tired

• Feeling cold

• Constipation

• Dry skin, hair, and nails

• Depression

If your thyroid medication dose is too high, you’ll have symptoms of hyperthyroidism. Signs your thyroid medication is too high include:

• Shakiness

• Diarrhea

• Feeling irritable

• Weight loss

• Feeling hot

When you are on the right dose of thyroid medication, you shouldn’t have thyroid symptoms. But if you don’t take your thyroid medication, you can still have complications of hypothyroidism.

Can hypothyroidism go away without treatment?

Most people with hypothyroidism will need to take levothyroxine for life. But if your hypothyroidism is due to other conditions that are reversible, it may improve. Common causes of hypothyroidism that can go away include:

• Pregnancy

• Medications 

• Autoimmune thyroiditis

• Iodine exposure

Why trust our experts?

Written by:

Maryann Mikhail, MD

Maryann Mikhail, MD, is a board-certified dermatologist and medical writer based in South Florida. She is the founder of Waverly DermSpa in Fort Lauderdale and holds a voluntary faculty position at the Dr. Phillip Frost Department of Dermatology and Cutaneous Surgery at the University of Miami MIller School of Medicine.

Reviewed by:

Karla Robinson, MD

Karla Robinson, MD, is a medical editor for GoodRx. She is a licensed, board-certified family physician with almost 20 years of experience in health through varied clinical, administrative, and educational roles.

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