By: Kimberly Dent-Ferguson, MBS, MPH, CPMC Research Analyst
Reviewed by: Ghada Haddad, MD, Cooper University Hospital and Tara Schmidlen, MS, LCGC, Coriell Institute for Medical Research 

What is Hypothyroidism?

Hypothyroidism, also known as underactive thyroid, is a condition in which the thyroid gland does not produce enough thyroid hormones1. The thyroid is a small, butterfly-shaped gland located at the base of the neck below the Adam's apple. This gland makes two hormones, triiodothyronine (T3) and thyroxine (T4). These two hormones play a significant role in metabolism, the process by which the body uses energy, by maintaining the rate fats and carbohydrates are used and by regulating production of proteins. Thyroid hormones also influence nervous system functions like body temperature, heart rate, and breathing, as well as other body functions like weight, brain development, muscle strength, skin dryness, menstrual cycles, and cholesterol levels2.

Hypothyroidism has a number of causes, including autoimmune disease, treatment for hyperthyroidism (overactive thyroid), history of radiation or removal of all or part of the thyroid gland, and certain medications. If left untreated, hypothyroidism can contribute to hypertension, hypercholesterolemia, and infertility. It can also worsen underlying cardiovascular disease and in severe cases, can cause the rare occurrence of myxedema coma, a life-threatening condition that results in depressed mental status, severe decrease in body temperature, as well as low blood pressure, low heart rate and slowed breathing.

There is no cure for hypothyroidism, but it can be controlled. The goal of hypothyroidism treatment is to closely replicate normal thyroid function using synthetic replacement hormones.

How Common is Hypothyroidism?

Hypothyroidism affects approximately 1 out of every 100 Americans. Hypothyroidism is more common among women than men and more common among Caucasians than any other race3.

To schedule a free telephone consultation to discuss your CPMC results with a board-certified genetic counselor, email This email address is being protected from spambots. You need JavaScript enabled to view it. .

Learn more about Hypothyroidism, from symptoms to understanding your risk, through the links below.

Page References

1. Simon, H. (2013). "Hypothyroidism." Retrieved June 24, 2014, from: http://umm.edu/health/medical/reports/articles/hypothyroidism.
2. National Endocrine and Metabolic Diseases Information Service. National Institutes of Health. (2013). "Hypothyroidism." Retrieved July 18, 2015, from: http://www.niddk.nih.gov/health-information/health-topics/endocrine/hypothyroidism/Pages/fact-sheet.aspx.
3. Hollowell, J.G., et al. "Serum TSH, T4, and thyroid antibodies in the United States Population (1988-1994): National Health and Nutrition Examination Survey (NHANES III)." J Clin Endocrinol Metab, 87 (2): 489-499.

Symptoms, Diagnosis, Treatment

Learn more about Hypothyroidism Learn More› ]

Risk Factors

Both genetic and non-genetic factors play a role in Hypothyroidism Learn More› ]

Reduce Your Risk

Risk-reducing behaviors for Hypothyroidism Learn More› ]

The CPMC Study

Learn how the CPMC Study identifies your risk for Hypothyroidism Learn More› ]