Hypothyroidism (underactive thyroid) is a condition in which the thyroid gland produces insufficient amounts of certain hormones. This interferes with the normal balance of chemical reactions in the body.

Hypothyroidism is more likely to occur in women older than 60. In the early stages of the condition there may be mild or no symptoms but over time hypothyroidism can cause numerous health problems such as obesity, infertility, heart disease and joint pain.

There are effective treatments for hypothyroidism that include medications such as synthetic thyroid hormones, which help manage the condition.



The symptoms of hypothyroidism vary relative to the severity of the hormone deficiency. However, most symptoms develop gradually throughout several years.

Symptoms of hypothyroidism may include:


  • Fatigue
  • Constipation
  • Dry skin
  • Increased sensitivity to cold
  • Hoarseness
  • Unexplained weight gain
  • Puffy face
  • Muscle weakness
  • Muscle aches, tenderness and stiffness
  • Joint pain, stiffness or swelling
  • Elevated blood cholesterol level
  • Slowed heart rate
  • Thinning hair
  • Heavier or irregular menstrual periods
  • Depression
  • Impaired memory


Advanced hypothyroidism is known as myxedema. It is a rare but life threatening condition. Symptoms include low blood pressure, decreased breathing, decreased body temperature, unresponsiveness and coma. In extreme cases, myxedema can be fatal.


Hypothyroidism in infants

Hypothyroidism mostly affects middle-aged and older women, although, it can affect anyone, including infants. Symptoms of hypothyroidism in infants include:


  • Yellowing of the skin and whites of the eyes (jaundice)
  • Frequent choking
  • A puffy face
  • Constipation
  • Poor muscle tone
  • Excessive sleepiness


Untreated hypothyroidism in infants can lead to severe physical and mental retardation.


Hypothyroidism in children and teens

Children and teens experience the same hypothyroidism symptoms as adults. However, in addition to those symptoms, children and teens may also experience:


  • Poor growth (short stature)
  • Delayed puberty
  • Delayed development of permanent teeth
  • Poor mental development



In hypothyroidism, the thyroid glands produces insufficient amount of hormones, which upsets the balance of chemical reactions in the body.

The hormones produced by the thyroid gland have a significant impact on the overall health. They control body temperature, influence the heart rate and help regulate the production of proteins among other things.

Hypothyroidism has numerous causes, including:


  • Autoimmune disease: Autoimmune disorders can affect the thyroid gland and affect its ability to produce hormones. A particular inflammatory disorder called Hashimoto’s thyroiditis is the most common cause of hypothyroidism.
  • Treatment for hyperthyroidism: Hyperthyroidism is treated with radioactive iodine or anti-thyroid medications to reduce thyroid function. However, this treatment may result in permanent hypothyroidism.
  • Thyroid surgery: Surgery to remove all or a large portion of the thyroid gland reduces hormone production.
  • Radiation therapy: Radiation treatment for cancers on the head and neck can affect the thyroid gland and cause hypothyroidism.
  • Medications: Certain medications, such as lithium, can contribute to hypothyroidism.
  • Congenital disease: Infants may be born without a thyroid gland or with a defective one. Moreover, some children inherit a form of hypothyroidism.
  • Pituitary disorder: In rare cases, a failure of the pituitary gland to produce sufficient thyroid-stimulating hormone (TSH) can cause hypothyroidism.
  • Pregnancy: Some women develop hypothyroidism during or after pregnancy often due to the production of antibodies to their own thyroid gland. Untreated hypothyroidism during pregnancy can cause miscarriage, premature delivery and preeclampsia.
  • Iodine deficiency: The mineral iodine is essential for the production of thyroid hormones. Its deficiency can lead to hypothyroidism. On the other hand, too much iodine can also cause hypothyroidism.


Risk factors

Risk factors for hypothyroidism include:


  • Being female and older than 60
  • Autoimmune diseases
  • Prior treatment with radioactive iodine or anti-thyroid medications
  • Radiation treatment to the head, neck or upper chest
  • Thyroid surgery (complete or partial thyroidectomy)
  • Pregnancy or childbirth



Possible complications of hypothyroidism may include:


  • Goiter: Continuous stimulation of the thyroid to release more hormones can cause for the gland to become larger (goiter). A large goiter can affect appearance as well as breathing or swallowing.
  • Heart problems: Hypothyroidism is associated with increasing levels of low-density lipoprotein (LDL) cholesterol (the “bad” cholesterol). Hypothyroidism can also lead to an enlarged heart and heart failure.
  • Mental health problems: Hypothyroidism can cause slowed mental functioning and depression that may become more severe over time.
  • Peripheral neuropathy: Long-term untreated hypothyroidism can cause damage to the peripheral nerves leading to muscle weakness or loss of muscle control.
  • Myxedema: Long-term undiagnosed hypothyroidism can lead to a rare, life-threatening myxedema. Myxedema can cause drowsiness, intense cold intolerance, lethargy, unconsciousness and coma.
  • Infertility: Low levels of thyroid hormone can affect ovulation and impair fertility. Hormone replacement therapy may not completely restore fertility.