The thyroid gland is a butterfly-shaped gland in the front of the neck. It makes hormones that control metabolism. Hypothyroidism is when the thyroid does not make enough thyroid hormones.

Thyroid Gland

Causes

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 women. 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 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, or rheumatoid arthritis

Symptoms

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

Fatigue
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
Difficulty concentrating
Blurred vision
Menstrual abnormalities or infertility

Symptoms of severe or long-term hypothyroidism may be:

Slow heart rate
Depressed breathing
Hypothermia—low body temperature
Coma

Diagnosis

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 other health conditions with similar symptoms.

Treatment

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

Prevention

There are no steps to prevent hypothyroidism.

RESOURCES:

American Thyroid Association
https://www.thyroid.org

Office on Women's Health
https://womenshealth.gov

CANADIAN RESOURCES

Health Canada
https://www.canada.ca

Thyroid Foundation of Canada
http://www.thyroid.ca

References:

Escobar-Morreale HF, Botella-Carretero JI, Escobar del Rey F, et al. Treatment of hypothyroidism with combinations of levothyroxine plus liothyronine. J Clin Endocrinol Metab. 2005;90(8):4946-4954.

Hypothyroidism in adults. EBSCO DynaMed website. Available at:
...(Click grey area to select URL)
Accessed September 25, 2020.

Roberts CG, Ladenson PW. Hypothyroidism. Lancet. 2004;363(9411):793-803.

Surks MI, Ortiz E, Daniels GH, et al. Subclinical thyroid disease: scientific review and guidelines for diagnosis and management. JAMA. 2004;291(2):228-238.

Thyroid hormone treatment. American Thyroid Association website. Available at: https://www.thyroid.org/thyroid-hormone-treatment.

Last reviewed September 2020 by EBSCO Medical Review Board Monica Zangwill, MD, MPH
Last Updated: 9/25/2020

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