This website is dedicated to the millions of thyroid patients who are being ignored and left to suffer unnecessarily, and to healthcare practitioners, who want to better serve those patients.

Complications of Untreated Hypothyroidism

What May Happen If the Disorder Is Untreated

Written by Eren Berber MD

See also Resistant Hypometabolism for more information.

If left untreated, hypothyroidism can progress and cause a multitude of complications. Understanding the symptoms of hypothyroidism and getting regular screenings to ensure an early diagnosis will prevent the onset of the complications listed below.

Birth Defects
If you are pregnant and have an untreated thyroid disorder, your child may have a higher risk of having birth defects than babies born to healthy mothers. Babies born to women with untreated thyroid disorders may have significant mental and physical development issues because thyroid hormones are vital for brain development. Fortunately, if these problems are addressed shortly after the birth, the child may experience healthy development. An abbreviated thyroid function test is part of the newborn screen. This usually includes a panel of blood tests performed on a newborn to exclude diseases.

When your thyroid over exerts itself in an effort to produce an adequate amount of hormones, the excessive stimulation may cause the thyroid gland to enlarge to the point where you have a bulge in your neck. This is known as a goiter.

Heart Problems
Hypothyroidismeven in its mildest formscan affect the health of your heart. An underactive thyroid can increase your risk of developing heart disease because it increases levels of “bad” cholesterol. Too much bad cholesterol can lead to atherosclerosis, hardening of the arteries, which can increase your risk of heart attacks and strokes. Hypothyroidism can also result in the buildup of fluid around the heart, a pericardial effusion, which may make it harder for the heart to pump blood.

If thyroid hormone levels are too low, it can affect ovulation and decrease a woman’s chances of conceiving. Even with proper treatment for hypothyroidismthyroid hormone replacement therapythere is no guarantee that the woman will be fully fertile.

Mental Health Issues
The symptoms of hypothyroidism can take a mental toll if left untreated. Mild hypothyroidism can cause mild forms of depression. But without treatment, the symptoms of hypothyroidism will increase. This can directly affect your mental state, and your depression may intensify as a result.

Moreover, untreated hypothyroidism has been associated with a gradual decrease in mental functioning.


Myxedema is the medical term for extreme hypothyroidismwhen the disorder has progressed for a long time with no treatment. Myxedema is very rare because it’s highly unlikely that you wouldn’t recognize the symptoms and seek treatment.

This form of hypothyroidism is life threatening. Myxedema can eventually slow metabolism to the point where you would fall into a coma. If you experience symptoms of myxedema, such as extreme fatigue or cold intolerance, seek medical treatment immediately.

The key to preventing the complications of hypothyroidism is to understand the disorder’s symptoms and seek proper medical care. Hypothyroidism is manageable with the right treatmentit doesn’t have to interfere with your everyday life.

Reviewed by Robert M. Sargis MD, PhD
Updated on: 03/13/14

View Sources ATA Hypothyroidism Web Booklet. American Thyroid Association Web site. Available at: Accessed June 10, 2009.
Mayo Clinic Hypothyroidism Complications page. Mayo Clinic Health Information Web site. Available at: Accessed June 10, 2009.
Skugor, M. The Underactive Thyroid: Hypothyroidism. In: The Cleveland Clinic Gide to Thyroid Disorders. New York: Kaplan Publishing; 2009:14-17.


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