Hypothyroidism may be caused by damage or injury to the thyroid. This may happen with:

  • Disorders of the immune system
  • Congenital defects of the gland or how it works
  • Surgery, medical procedures, or radiation therapy for thyroid treatment

It may also be caused by:

  • Problems with the pituitary glands which sends signals to the thyroid
  • Iodine deficiency—(rare in the US) iodine is needed to make thyroid hormones

In some people, the cause of hypothyroidism may remain unknown.

Risk Factors

Hypothyroidism is more common in females. It is also more common in those aged 65 years and older. Other factors that may increase the chance of hypothyroidism include:

  • Family history of hypothyroidism
  • Recently gave birth, risk is higher if there was hypothyroidism in past
  • Past surgery, radiation therapy, or radioablation in the neck region
  • Autoimmune diseases, such as:
  • Systemic lupus erythematosus
  • Celiac disease
  • Type 1 diabetes
  • Rheumatoid arthritis



Symptoms may not always appear. When they do, they may include:

  • Feeling tired
  • Weakness
  • Coarse, brittle hair, and/or hair loss
  • Facial puffiness
  • Dry skin
  • Swollen hands or feet
  • Cold intolerance
  • Weight gain
  • Constipation
  • Achy feeling all over
  • Depression and irritability
  • Memory loss
  • Problems focusing
  • Blurred vision
  • Menstrual problems or infertility

Symptoms of severe or long-term hypothyroidism may be:

  • Slow heart rate
  • Depressed breathing
  • Hypothermia—low body temperature
  • Coma


The doctor will ask about symptoms and past health. A physical exam will be done.

Blood tests can check levels of thyroid hormones. Abnormal levels will suggest a problem with the thyroid. Other tests may be done to rule out health conditions with similar symptoms.



Medicine will be used to replace the missing thyroid hormones. It should ease symptoms. The amount of medicine needed may change over time. Regular check ups will help treatment stay on track.


There are no steps to prevent hypothyroidism.

This content is reviewed regularly and is updated when new and relevant evidence is made available. This information is neither intended nor implied to be a substitute for professional medical advice. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with questions regarding a medical condition.

Edits to original content made by Denver Health.