The thyroid gland is a gland in the front of the neck that produces hormones that control metabolism. Hypothyroidism occurs when the thyroid gland doesn't produce enough thyroid hormone. The most common form of hypothyroidism is Hashimoto's thyroiditis.

Causes of Hypothyroidism

Hashimoto's thyroiditis is an autoimmune disorder. The immune system produces antibodies that attack cells of the thyroid gland.

Hypothyroidism may also be caused by:

  • Congenital defects of the gland or how it works
  • Surgery or radiation therapy for thyroid cancer treatment
  • Iodine deficiency 
  • Pituitary deficiency

Are You at Risk?

Hypothyroidism is more common in women and those aged 65 years and older. Other factors that may increase your risk of hypothyroidism include:

  • Family history of hypothyroidism
  • Autoimmune diseases, such as systemic lupus erythematosus, type 1 diabetes or rheumatoid arthritis
  • Certain health conditions, such as infiltrative disorders, cancer or infections
  • Surgery, radiation therapy or radioablation in the neck region
  • Certain medications, such as lithium, iodine or interleukins
  • Pituitary adenoma

Symptoms of Hypothyroidism

You may not have symptoms of hypothyroidism. In those that have symptoms, hypothyroidism may cause:

  • Fatigue
  • Weakness
  • Coarse, brittle hair and hair loss
  • Facial puffiness
  • Dry skin
  • Swollen hands or feet
  • Cold intolerance
  • Weight gain
  • Constipation
  • Achy feeling all over
  • Depression and irritability
  • Memory loss
  • Difficulty concentrating
  • Blurred vision
  • Menstrual abnormalities or infertility

Symptoms of severe or long-term hypothyroidism causes:

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

Hypothyroidism: Diagnosis & Treatment

Tests may include blood tests to check levels of thyroid stimulating hormone (TSH) and/or free T4. Your doctor may recommend other tests to rule out health conditions that are similar to hypothyroidism.

Thyroid replacement therapy involves medication that replaces the function of the thyroid gland. This therapy may also prevent cancer cell growth in people who had surgery or radiation treatment for thyroid cancer.

People with Hashimoto's thyroiditis are monitored as long as they have normal thyroid function and remain symptom-free. Once function decreases or symptoms appear, treatment is started with thyroid replacement therapy.

Hypothyroidism Prevention

Talk to your doctor about annual screenings if you're at high risk for developing hypothyroidism.


Content was created using EBSCO’s Health Library. Edits to original content made by Rector and Visitors of the University of Virginia. This information is not a substitute for professional medical advice.