Key takeaways:
Hypothyroidism can affect many body systems. But when treated, your symptoms can fully resolve.
Untreated hypothyroidism can lead to serious complications, including heart disease and nerve damage. In rare cases, it can be fatal.
Most people with hypothyroidism have to take thyroid hormone replacement long term. You will need ongoing thyroid level checks to ensure you are on the right dose.
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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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.
Certain medications can affect your thyroid hormone levels. Some common ones are:
Amiodarone (Pacerone)
Bexarotene (Targretin)
Antidepressants (like sertraline)
Anti-seizure medicines (like carbamazepine , phenytoin, phenobarbital)
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.
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 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.
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.
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.
Having one autoimmune disease increases your chances of getting others. Autoimmune diseases include conditions like:
Alopecia areata (hair loss)
Vitiligo (loss of skin color)
Pernicious anemia (decrease in red blood cells).
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.
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)
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.
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.
Untreated hypothyroidism can lead to serious mental and physical health problems. Complications of untreated hypothyroidism can include the following.
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.
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.
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.
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.
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.
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.
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.
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.
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
Dry skin, hair, and nails
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.
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
Hypothyroidism is easy to diagnose and treat. The hard part is realizing that your symptoms might be coming from your thyroid. If you regularly feel fatigued, cold, or irritable, let your provider know. Other symptoms may include weight gain and hair loss.
Getting treatment early can prevent complications of untreated hypothyroidism. This is especially important if you are planning a pregnancy or have risk factors.
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