Hypothyroidism (Underactive Thyroid)

What is hypothyroidism?

Hypothyroidism (underactive thyroid disease) is a condition that happens when your thyroid gland doesn’t make or release enough hormone into your bloodstream. As a result, your metabolism slows down. This can cause unintentional weight gain and make you feel exhausted all the time.

Although weight gain and fatigue aren’t specific to hypothyroidism, a simple blood test can help your healthcare provider check for this condition.

In general, hypothyroidism is very treatable. Most people can manage the condition with medication and regular follow-up visits with their endocrinologist.

Left untreated over long periods of time, hypothyroidism can become life-threatening. If you develop new symptoms, it’s important to get an evaluation.

Types of hypothyroidism

There are four main types of hypothyroidism:

• Primary hypothyroidism directly impacts your thyroid and causes it to make low levels of thyroid hormones. In turn, your pituitary gland makes more thyroid stimulating hormone (TSH). Autoimmune conditions like Hashimoto’s disease can cause it, or it can happen after thyroid gland surgery or radiation therapy. Primary hypothyroidism is the most common type.
• Secondary hypothyroidism occurs when you have an underactive pituitary gland (a pea-sized gland at the base of your brain). This rare type of hypothyroidism prevents your pituitary gland from sending TSH to your thyroid gland.
• Tertiary hypothyroidism happens when your hypothalamus (a structure in your brain that keeps your body in a stable state called homeostasis) doesn’t make enough thyrotropin-releasing hormone (TRH). As a result, your pituitary gland can’t make enough TSH.
• Subclinical hypothyroidism, also known as mild thyroid failure, happens when you have slightly elevated TSH levels, but all other thyroid hormone levels are within a typical range. Subclinical hypothyroidism usually goes away on its own in about three months.

How common is hypothyroidism?

Hypothyroidism can affect anyone. It’s most common among people assigned female at birth (AFAB) over age 60, particularly after menopause.

What are the symptoms of hypothyroidism?

Hypothyroidism symptoms usually develop slowly over time. In some cases, it can take years. Some possible symptoms include:

• Brain fog (forgetfulness or difficulty concentrating).
• Depression and anxiety.
• Dry, coarse skin and hair.
• Elevated blood cholesterol levels.
• Feeling tired (fatigue).
• Frequent or heavy menstrual periods.
• Hoarseness.
• Inability to tolerate cold temperatures.
• Numbness or tingling in your hands.
• Physical changes in your face (drooping eyelids, puffiness around your eyes).
• Soreness or muscle weakness.
• Unexplained weight gain.

If you develop any signs of hypothyroidism, let your healthcare provider know. They can run tests to confirm a diagnosis.

What causes hypothyroidism?

Hashimoto’s disease is the most common cause of hypothyroidism. It’s an autoimmune disease, so it happens when your immune system attacks your thyroid.

Other hypothyroidism causes include:

• Certain medications, including lithium, thalidomide and amiodarone.
• Conditions present at birth, like being born with no thyroid gland or a thyroid gland that doesn’t work properly.
• Iodine deficiency (when you don’t have enough iodine in your body).
• Pituitary gland disorders, including noncancerous tumors.
• Thyroiditis (inflammation of the thyroid that can happen after a viral illness or pregnancy).

What are the risk factors for hypothyroidism?

Anyone can get hypothyroidism. But you’re more likely to develop the condition if you were assigned female at birth (AFAB) or have a/an:

• Autoimmune disease.
• Genetic predisposition (a biological parent or sibling with the condition).
• History of thyroid surgery, including thyroid gland removal.
• Pregnancy.
• Previous history of head and neck radiation therapy.
• Starting or stopping certain medications.

What are the complications of hypothyroidism?

With treatment, hypothyroidism complications aren’t very common. But left untreated, an underactive thyroid can lead to other health conditions like:

• Goiter.
• Heart issues.
• Infertility.
• Miscarriage or birth defects.
• Peripheral neuropathy.
• Myxedema coma (rare complication that can affect multiple organs and is life-threatening).

How is hypothyroidism diagnosed?

A provider will press gently around your thyroid during a physical examination to see if your gland feels swollen. They’ll also ask about your symptoms and review your medical history in detail.

Healthcare providers usually run thyroid tests to get an accurate hypothyroidism diagnosis. This is because an underactive thyroid can cause symptoms that mimic other, unrelated health conditions. Thyroid blood tests measure the level of thyroid-stimulating hormone (TSH) in your blood as well as the levels for each thyroid hormone (T3 and T4).

You might also need imaging tests of your thyroid, which could include:

• Ultrasound.
• CT (computed tomography) scan.
• Thyroid uptake scan (a type of nuclear medicine imaging).

How is hypothyroidism treated?

The most common hypothyroidism treatment is hormone replacement therapy. Levothyroxine (Synthroid®, Levo-T®) is a medication that replaces the hormones that your thyroid can’t make naturally. Most people take it in the mornings on an empty stomach. Taken daily, levothyroxine can even out your hormone levels and eliminate your symptoms.

It’ll take a bit of trial and error to find the right dosage. To do this, your provider will run routine thyroid blood tests until your TSH levels even out.

You’ll need to take hypothyroidism medication for the rest of your life. With careful management and regular follow-ups with your healthcare provider, you can lead a normal and healthy life.

How soon after treatment will I feel better?

Medications like levothyroxine start leveling out your hormones right away. But it usually takes a few weeks to notice an improvement in your symptoms.

Remember, you’ll probably need to take hypothyroidism medication for the rest of your life. If you stop taking it, your symptoms will likely return.

Can hypothyroidism be prevented?

You can’t prevent hypothyroidism. If you develop symptoms like the ones mentioned above, let your healthcare provider know right away. Early diagnosis and treatment are the best ways to reduce your risk of complications and live a healthy life.

Can hypothyroidism be cured?

Currently, there’s no cure for hypothyroidism. But you can successfully manage the condition with hormone replacement therapy.

How long hypothyroidism lasts

Hypothyroidism is a lifelong condition. If you receive a diagnosis, you’ll need to take medication every day to keep your thyroid hormone levels in check.

Outlook for hypothyroidism

People with hypothyroidism have a great outlook if they receive treatment. Left untreated, an underactive thyroid can cause life-threatening conditions like myxedema.

When should I see my healthcare provider?

If you develop hypothyroidism symptoms like weight gain, dry skin or fatigue, let your healthcare provider know. They may want to run tests to rule out other conditions.

If you already take medication for hypothyroidism, let your provider know if your symptoms come back or persist. They may need to adjust your dosage.

When should I go to ER?

You should call 911 or head to your nearest emergency room if you develop the following symptoms:

• Difficulty breathing.
• Extreme lethargy.
• Low body temperature (hypothermia).
• Low blood pressure (hypotension).
• Slow heartbeat (bradycardia).

These symptoms may indicate myxedema, a life-threatening condition. If you’re experiencing these things, you need immediate treatment.

Can I get hypothyroidism during pregnancy?

People with an underactive thyroid (especially primary hypothyroidism) have an increased risk of infertility and pregnancy complications like gestational hypertension and postpartum hemorrhage. But regular thyroid function tests and medication can help you have a healthy pregnancy. If you have hypothyroidism and think you might be pregnant, ask your healthcare provider how to manage your condition.

What should I know about hypothyroidism in children?

Some people are born with an underactive thyroid or no thyroid at all. When this happens, healthcare providers call it congenital hypothyroidism.

Providers test all newborns for hypothyroidism. Thyroid hormone is essential for an infant’s growth and brain development. If your baby has congenital hypothyroidism, your provider will begin treatment in the first weeks of life to prevent intellectual disabilities and developmental delays.

Is hypothyroidism genetic?

It can be, but it’s not always the case. Parents can pass hypothyroidism down to their biological children. But in many cases, there are environmental factors at play, like having thyroiditis, developing an iodine deficiency or taking certain medications.

Does hypothyroidism cause weight gain?

Left untreated, hypothyroidism can cause you to gain weight. Many people lose weight once they start hormone replacement therapy. Still, it’s a good idea to talk to your healthcare provider about a nutrition and exercise plan that works for you.

What happens if hypothyroidism isn’t treated?

Without treatment, hypothyroidism can become a serious and life-threatening medical condition.

Can hypothyroidism cause anxiety?

Yes, it can. In fact, any thyroid gland dysfunction can cause both anxiety and depression. But hypothyroidism is the most common culprit. Ask your healthcare provider about ways to reduce stress and practice mindfulness.