[Mayoclinic] Hypothyroidism – Latest updated medical information and knowledge



Hypothyroidism is a condition in which the thyroid gland does not produce enough of certain important hormones.

Hypothyroidism may not cause symptoms in its early stages. If left untreated, over time it can cause health problems such as obesity, joint pain, infertility, and cardiovascular disease.

Modern thyroid function tests are now available to help diagnose hypothyroidism accurately. Treatment with synthetic thyroid hormone is usually simple, safe, and effective at the right dose for the individual patient.


Signs and symptoms of hypothyroidism vary widely, depending on the extent of the hormone depletion. Symptoms tend to progress slowly, often over many years.

At first, you may not notice the symptoms of hypothyroidism (fatigue, weight gain) or simply assume that your body is not feeling well. But as your metabolism continues to slow down, you may develop more obvious symptoms.

Signs and symptoms of hypothyroidism include:

  • Tired
  • Scare cold
  • Constipation
  • Dry skin
  • Weight gain
  • Round face
  • Hoarseness
  • Muscle weakness
  • Increased blood cholesterol
  • Muscle pain, cramps
  • Pain, stiffness and swelling of joints
  • Irregular menstruation
  • Hair loss
  • Slow heart rate
  • Depression
  • Memory decline
  • Large thyroid gland (goiter)

Hypothyroidism in infants

This syndrome is common in middle-aged and older women. However, everyone is at risk, including infants. A baby born with no thyroid or an underactive thyroid may initially have a few signs and symptoms, which can be:

  • Yellow skin, yellow eye conjunctiva. In most cases, this happens in a child’s liver that cannot metabolize bilirubin (created when red blood cells are destroyed).
  • Shortness of breath
  • Large and protruding tongue
  • Crying hoarsely
  • Umbilical hernia.

As the disease progresses, the infant may have difficulty feeding and may not grow and develop normally. Signs and symptoms:

  • Constipation
  • Poor muscle tone
  • Sleeping too much

If infants are left untreated, even a mild form can lead to severe mental and physical retardation.

Hypothyroidism in children and adolescents

Usually, the symptoms and signs in children and adolescents are similar to those in adults. However, you may also experience the following symptoms:

  • Slow growth (resulting in short stature)
  • Delayed growth of permanent teeth
  • Late puberty
  • Poor mental development.

When to see a doctor?

When you feel fatigued for no apparent reason or have any of the other signs or symptoms of hypothyroidism, such as dry skin, round face, constipation, or hoarseness.

If you are on hormone replacement therapy, schedule regular follow-up visits as recommended by your doctor. Initially, it is important to make sure that you are receiving the correct dose of medication. And over time, the dosage you need may change.


When the thyroid gland does not produce enough hormones, the balance of chemical reactions in the body can be disturbed. There are many causes including autoimmune disease, treatment for hyperthyroidism, radiation therapy, thyroid surgery, and certain medications.

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Your thyroid is a small, butterfly-shaped gland located in the front under the neck, just below the apple of the Amdam (larynx). The hormones produced by the thyroid gland – triiodothyronine (T3) and thyroxine (T4) – have a huge impact on your health, affecting all aspects of your metabolism. These hormones also affect the control of important functions, such as body temperature and heart rate.

Hypothyroidism occurs when the thyroid gland does not produce enough hormones. Hypothyroidism can be caused by a number of factors, including:

  • Autoimmune disease A common cause of hypothyroidism is Hashimoto’s autoimmune thyroiditis. Autoimmune disorders occur when the immune system produces antibodies against the body’s own tissues. Sometimes this process affects the thyroid gland. And when this happens, it affects your ability to produce thyroid hormone

Scientists aren’t sure why this is, but it could be a combination of factors such as genes and environmental stimuli.

  • Over-response to treatmentborder People who produce too much thyroid hormone (hyperthyroidism) are often treated with radioactive iodine and antithyroid drugs. The goal of treatment is to return thyroid function to normal. But sometimes, correcting hyperthyroidism can reduce thyroid hormone production too much, leading to permanent hypothyroidism.
  • Thyroid surgery. Removal of a large part or all of the thyroid gland can reduce or stop hormone production. In that case, lifelong thyroid hormone therapy is required.
  • Radiation therapy Radiation therapy used to treat cancer of the head and neck can affect the thyroid gland, leading to hypothyroidism.
  • Medicine – Many drugs can cause hypothyroidism. An example is lithium – used to treat some mental disorders. If you’re on medication, talk to your doctor about its effects on your thyroid.

Less common causes:

  • Congenital disease Some babies are born with a defect or no thyroid gland. In most cases, the thyroid gland develops abnormally for no apparent reason, while others have a genetic disorder. Usually, babies with congenital hypothyroidism are normal at birth. That’s one reason why most states now require newborn thyroid screening.
  • Pituitary gland disorder A relatively rare cause of hypothyroidism is the pituitary gland not producing enough TSH – usually a benign tumor in the pituitary gland.
  • Pregnant Some women develop hypothyroidism during or after pregnancy (postpartum hypothyroidism), usually because their bodies produce antibodies against the pituitary gland. If left untreated, the syndrome increases the risk of miscarriage, premature delivery, and pre-eclampsia – a condition that causes a woman’s blood pressure to rise dramatically during the third trimester of pregnancy. It can also seriously affect a developing fetus.
  • Iodine deficiency The trace mineral iodine – found mainly in seafood, seaweed, plants grown in iodine-rich soil and iodized salts – is essential for thyroid hormone production. Too little iodine can lead to hypothyroidism, and too much can worsen hypothyroidism in people who already have it. In some parts of the world, iodine deficiency is common, but the addition of iodine to table salt has largely eliminated the problem in the United States.
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Risk factor

Anyone can develop hypothyroidism, but the risk is increased when the following factors are present:

  • Woman
  • More than 60 years old
  • Family history of thyroid disease.
  • Have an autoimmune disease (type 1 diabetes, celiac disease, etc.)
  • Treatment with radioactive iodine or antithyroid drugs.
  • Had radiation therapy to the neck or upper chest.
  • Had thyroid surgery
  • Are pregnant or within 6 months of giving birth.


If left untreated, hypothyroidism can cause many complications:

  • Goiter Continuous stimulation of the thyroid gland to release more hormones can cause the gland to become enlarged – a condition known as a goiter. Although generally not uncomfortable, a large goiter can affect appearance and can interfere with swallowing or breathing.
  • Cardiovascular problems Hypothyroidism may also be associated with an increased risk of heart disease and heart failure, mainly because high levels of lipoprotein cholesterol (LDL) — the “bad” cholesterol — can occur in people with an underactive thyroid. least.
  • Mental health problems Depression can appear early in the hypothyroid phase and can get worse over time. Hypothyroidism can also cause nerve function to slow down.
  • Peripheral neuropathy Uncontrolled long-term hypothyroidism can damage your peripheral nerves. These are nerves that carry information from your brain and spinal cord to the rest of your body – your arms and legs, for example. Peripheral neuropathy can cause pain, numbness, and tingling in the affected areas.
  • Myxedema disease (Myxedema) – This rare, life-threatening condition is the result of long-term undiagnosed hypothyroidism. Its signs and symptoms include fear of the cold and extreme drowsiness, followed by a deep coma and unconsciousness.
  • Infertility Low thyroid hormone levels can interfere with ovulation, impairing fertility. In addition, certain causes of hypothyroidism — such as autoimmune disorders — can also impair fertility.
  • Birth defects Babies born to women with untreated thyroid disease may have a higher risk of birth defects than babies born to healthy mothers. These children are also prone to serious intellectual and developmental problems.

Infants with untreated hypothyroidism from birth are at risk for serious developmental problems, both physically and mentally. But if the condition is diagnosed within the first few months of life, the chances of it developing normally are very good.

Link to the original post: Hypothyroidism – Symptoms and causes – Mayo Clinic

Translation: Ly Anh
Editing: Kim Luan

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