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What Are Hyperthyroidism And Hypothyroidism?
Updated on January 31, 2024
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What Are Hyperthyroidism And Hypothyroidism?

Key Takeaways

Hyperthyroidism and hypothyroidism are common forms of thyroid diseases. Thyroid disease is an umbrella term for medical conditions that affect the thyroid gland’s normal hormone production.

The thyroid gland is a small organ located at the base of your neck. It wraps around your windpipe or trachea and is responsible for thyroid hormone production.1

Our in-house medical reviewer, Dr. Rizza Mira, says it is regulated by the pituitary gland to make hormones that “enable every single cell in the body to work."

The thyroid gland is essential to every function in the human body. It controls your metabolism, stimulates the growth and development of body organs, and manages their function.

What Are Hyperthyroidism And Hypothyroidism? 1

The thyroid produces hormones Triiodothyronine (T3) and Thyroxine (T4) that control how much energy your body’s cells should use. They also influence essential body functions, such as temperature regulation and heart rate.

A properly working thyroid produces enough hormones to keep your body functioning well. When the thyroid malfunctions, it can lead to thyroid problems.

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Who Is Affected By Thyroid Disease?

Thyroid disease can affect anyone regardless of age and gender. According to the American Thyroid Association (ATA), around 20 million people in the U.S. have a thyroid disorder.2

Thyroid dysfunction like hypothyroidism can be present at birth. A person may also develop it from exposure to risk factors or if they’re genetically predisposed to the condition.

Certain people can be at higher risk. For example, thyroid problems often occur in women after menopause or when they’re aged 60 or older. 

Women are also five to eight times more likely to develop thyroid disorders than men.2,3

Other factors that can increase your risk of developing thyroid disorders include:2

  • A family history of thyroid disease
  • Some diseases (e.g., pernicious anemia, type 1 diabetes, and lupus)
  • Taking a medication high in iodine (e.g., amiodarone)
  • Past treatments for thyroid cancer (e.g., thyroidectomy and radiation)
  • A diet high in goitrogens (e.g., broccoli, cabbage, kale, cassava, and turnips)
  • Iodine deficiency
  • Thyroid nodules


Thyroid disease is a term referring to conditions affecting your thyroid hormone production. It can affect people of all ages and gender. They can be present at birth or gene-related. Exposure to certain risk factors can also increase your chances of developing thyroid problems.

What Are The Early Signs of Thyroid Problems

The early signs of thyroid problems depend on whether you have an underproduction or overproduction of thyroid hormones. Some of the common symptoms include:

  • Lack of energy even after getting enough sleep
  • Sudden unexplained weight gain or weight loss
  • Mood swings, irritability, anxiety, or depression
  • Sleep disturbances, like insomnia or excessive sleepiness
  • Dry or rough skin
  • Hair loss
  • Muscle weakness or joint pain
  • Increased or decreased heart rate
  • Changes in the menstrual cycle, like lighter or heavier periods or irregular cycles
  • Goiter or visible swelling in the neck caused by an enlarged thyroid gland

Take note that health conditions other than thyroid problems may also cause these symptoms. A proper medical evaluation is essential to diagnose their cause.

What is Hypothyroidism (Underactive Thyroid)

Hypothyroidism is a health condition where your thyroid gland doesn’t produce enough thyroid hormones. It can slow down your metabolism.

Untreated hypothyroidism can result in health problems like obesity and joint pain.4 The condition can also affect the heart and brain in the long run. 

Common Hypothyroidism Symptoms

You may not notice symptoms at the beginning. The signs may also vary depending on how severe your hypothyroidism is.

Some signs of an underactive thyroid include:

  • Feeling tired
  • Intolerance to cold temperatures
  • Poor memory
  • Heavy menstruation 
  • Coarse hair and dry skin
  • Hoarse voice
  • Constipation
  • Puffy face
  • Weight gain
  • High blood cholesterol level
  • Muscle and joint aches
  • Hair loss
  • Slowed heart rate
  • Depression
  • Goiter or enlarged thyroid gland

Hypothyroidism in Infants

Infants with congenital hypothyroidism may show subtle signs. Symptoms may also progress slowly. 

“Because there are no obvious signs of congenital hypothyroidism at birth, newborns are screened using a blood test for this disorder. Left untreated, the condition can affect neurological functioning and may lead to lifetime morbidity," Dr. Mira explains.

Babies with low thyroid hormones may show these signs and symptoms:

  • Yellow skin and whites of the eyes (jaundice)
  • A large and protruding tongue
  • Difficulty breathing
  • Hoarse-sounding cries
  • A belly button that sticks out too far (umbilical hernia)
  • Poor appetite
  • Feeding problems

Hypothyroidism in Children & Teenagers

Children and teens with an underactive thyroid may show similar symptoms to adults with the same condition. In addition, they will experience symptoms of delayed development.4

The signs of hypothyroidism in children and adolescents are:

  • Slow physical growth (e.g., short height)
  • Delayed eruption of adult teeth
  • Poor brain development


Hypothyroidism, or the medical condition called underactive thyroid, means your thyroid isn't releasing enough thyroid hormones. It can slow down metabolism and affect one's growth and development, especially in children and adolescents. It can be present at birth but show no obvious signs.

What is Hyperthyroidism (Overactive Thyroid)

Sometimes the thyroid may release too much thyroid hormone. It can cause your body to burn energy more quickly. This condition is known as an overactive thyroid or hyperthyroidism.1

Common Hyperthyroidism Symptoms

Hyperthyroidism can cause a range of symptoms. But it’s unlikely you’ll experience all of them. 

Symptoms may develop gradually or appear suddenly. The severity of these symptoms may also vary for each person.5 

Here are some signs of hyperthyroidism:

  • Feeling nervous, anxious, and irritable most of the time
  • Having a hard time staying still
  • Weight loss
  • Irregular menstrual cycle
  • Mood swings
  • Difficulty sleeping
  • Fatigue
  • Feeling sensitive to heat
  • Muscle weakness and tremors 
  • Diarrhea
  • Peeing more often than usual
  • Feeling thirsty
  • Itchiness
  • Loss of interest in sex

Hyperthyroidism in Infants

Congenital hyperthyroidism is rare but can be life-threatening. It’s common in babies born to mothers with Graves disease. 

Graves disease is an autoimmune disorder causing overproduction of thyroid hormone or hyperthyroidism.

“Unlike hypothyroidism, high levels of thyroid hormones in newborns are temporary. It’s often caused by the passage of excess hormones from mother to child,” says Dr. Mira.

More than 95% of these babies show symptoms in their first month. Sometimes, the signs don’t appear until their second month.6

Common signs and symptoms of hyperthyroidism in infants are:

  • Failure to gain weight
  • Vomiting and diarrhea
  • Appearing irritated
  • Struggling to feed
  • High blood pressure
  • Abnormally fast heartbeat
  • Protruding eyes
  • Congenital goiter
  • Prominent forehead (frontal bossing)
  • Small head size

The severity of these symptoms and how soon they appear depend on whether the mother is taking antithyroid medications.

Babies born to mothers taking antithyroid medications may not show signs until the drugs are metabolized. But if the mother isn’t on medications, the newborn may show signs.

Infants born with hyperthyroidism usually recover at the age of six months. The condition rarely lasts longer.

Hyperthyroidism in Children & Teenagers

More than 90% of hyperthyroidism cases in children and adolescents are due to Graves disease. About 80% occur during puberty when the risk of Graves is higher.6

Other causes of hyperthyroidism in children include thyroid gland inflammation, infection, or the use of certain drugs.

An overactive thyroid usually doesn’t affect puberty. But pubescent girls may experience irregular menstruation or not menstruate at all (amenorrhea).

It can also cause growth-related issues, like advanced growth and bone aging. 

Other signs and symptoms of hyperthyroidism in kids and teens are:

  • Difficulty sleeping
  • Unable to stay still
  • Emotional lability or quick and intense change in mood
  • Difficulty focusing
  • Declining school performance
  • Feeling overly warm
  • Excessive sweating
  • Fatigue
  • Weight loss
  • Frequent bowel movements or diarrhea


Hyperthyroidism is described as having an overactive thyroid, causing you to burn energy quickly. 95% of babies born with hyperthyroidism show symptoms during their first month. Hyperthyroidism can affect puberty and cause growth-related issues like advanced growth and bone aging.

Thyroid Issues In Women

Women have a higher chance of developing thyroid disease than men. According to statistics, 1 out of 8 women develops a thyroid problem in her life.

Dr. Mira explains that thyroid problems occur more in women than men because of their autoimmune nature.

Thyroid issues may cause these problems in reproductive women:

  • Irregular menstrual cycles
  • Absent menstruation (amenorrhea)
  • Difficulty getting pregnant
  • Getting pregnant
  • Health issues during pregnancy
  • Early menopause


Hyperthyroidism and hypothyroidism are thyroid disorders linked to the production of thyroid hormones. They occur when the thyroid gland produces too much or too few hormones. They cause a range of symptoms

How To Tell If You Have Thyroid Problems

Thyroid disease can be hard to diagnose based on symptoms alone. You might confuse them with other conditions with similar signs. 

It’s best that you seek medical help from your doctor or a healthcare professional. They can help diagnose thyroid disorders with the proper tests.

Certain blood tests can help determine if thyroid disease is causing your symptoms. For example, a thyroid panel can check your thyroid hormone levels including:

  • Thyroid-stimulating hormone (TSH)
  • Free T3
  • Free T4 

The doctor will compare your results to the normal range of people of the same age. It can help them assess how well your thyroid gland is functioning.8

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Updated on January 31, 2024
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8 sources cited
Updated on January 31, 2024
  1. Thyroid Disease.” Cleveland Clinic.
  2. General Information/Press Room.” American Thyroid Association (ATA).
  3. The thyroid gland in postmenopausal women: physiology and diseases.” Menopause Review.
  4. Hypothyroidism (underactive thyroid).” Mayo Clinic.
  5. Overactive thyroid (hyperthyroidism).” NHS UK.
  6. Hyperthyroidism in Infants and Children.” MSD MANUAL.
  7. “Monica C. Skarulis, M.D., Chief Clinical Endocrine Section, Director Inter-Institute Endocrine Training Program.” National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK).
  8. Understanding thyroid tests.” National Center for Biotechnology Information.
Dr. Rizza Mira
Dr. Rizza Mira
Medical Reviewer
Dr. Rizza Mira is a medical doctor and a general practitioner who specializes in pediatrics, nutrition, dietetics, and public health.

As a pediatrician, she is dedicated to the general health and well-being of children and expecting parents. She believes that good nutrition, a healthy lifestyle, and prevention of illness are key to ensuring the health of children and their families.

When she’s not in the hospital, Rizza advocates and mobilizes causes like breastfeeding, vaccination drives, and initiatives to prevent illness in the community.
Cristine Santander
Cristine Santander
Content Contributor
Cristine Santander is a content writer for KnowYourDNA. She has a B.S. in Psychology and enjoys writing about health and wellness.
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