What is Hypothyroidism?

Hypothyroidism is a condition in which either the thyroid gland (a small butterfly-shaped gland in the front of your neck) does not make enough thyroid hormone, or the pituitary gland does not make enough thyroid stimulating hormone, or TSH (a hormone that tells the thyroid gland to make thyroid hormone). Your body uses thyroid hormone to regulate its metabolism.

What Are Some of the Different Types of Hypothyroidism?

Congenital hypothyroidism (CH) happens when a baby is born with a thyroid that is not fully developed, not developed at all, or unable to make thyroid hormone. CH can also happen when the pituitary gland (small gland in the brain that controls other glands in the body) does not make enough thyroid stimulating hormone (TSH).

Acquired hypothyroidism occurs later in life. Common causes include:

  • Autoimmune hypothyroidism (AH), a condition in which the body’s immune system attacks and destroys the thyroid gland to varying degrees. AH is also called Hashimoto’s thyroiditis.
  • Certain medications (such as lithium) can cause hypothyroidism
  • Secondary hypothyroidism, a condition in which the pituitary gland makes less of TSH.

What are the Common Signs of Hypothyroidism?

  • Poor growth in children
  • Fatigue (tiredness) or weakness
  • Constipation
  • Weight gain
  • Sensitivity to cold temperatures
  • Dry and rough skin and hair
  • Unusual hair loss
  • Hoarse voice
  • Irregular or heavy periods (in girls)
  • Puffy, swollen or droopy eyelids
  • Slow heart rate
  • Large thyroid gland (goiter)
  • Dull reflexes

Rev. 5/2020. MassGeneral Hospital for Children and Massachusetts General Hospital do not endorse any of the brands listed on this handout. This handout is intended to provide health information so that you can be better informed. It is not a substitute for medical advice and should not be used to treatment of any medical conditions.