Fact Sheet
Hypothyroidism
and Heart Disease
What is the thyroid gland
and what does it do?
The thyroid gland, located in your neck, makes two kinds of
thyroid hormones: T4 (thyroxine) and T3 (triiodothyronine).
Thyroid hormones regulate how your body uses and stores
energy. These hormones also help your brain, heart, muscles,
and other organs work properly. They affect your breathing,
nervous system, body temperature, and weight.
What is hypothyroidism and
what are its symptoms?
How is hypothyroidism diagnosed?
Your doctor diagnoses hypothyroidism by doing a physical exam
and asking you about your symptoms. The doctor will look at
results of blood tests of your hormone levels before making
decisions about treatment.
What is the treatment for
hypothyroidism?
The goal of treatment is to make sure you have normal levels of
thyroid hormone all of the time. People who have hypothyroidism
must take a pill containing thyroid hormone every day to replace
Hypothyroidism, also called an underactive thyroid, occurs when
your thyroid gland makes too little thyroid hormone. When you
don’t have enough thyroid hormone, you won’t feel well and can
have health problems.
Symptoms include
• Being tired
• Feeling sluggish
• Feeling cold
• Gaining weight
• Having dry skin and hair
• Being constipated
• Having irregular menstrual periods
These symptoms can occur with other health problems as well.
D i d y o u kn o w?
Hypothyroidism is more common in women
and in people older than age 50.
Thyroid
Gland
the hormone they lack. The most common thyroid hormone
treatment is levothyroxine, a synthetic (manufactured) form of T4.
Levothyroxine is exactly the same as the T4 made by the body
and it works the same way as your own thyroid hormone.
Why does hypothyroidism increase
your risk for heart disease?
Both thyroid hormones (T4 and T3) are related to heart disease
because they affect your heart rate and the amount of blood
pumped by your heart. Thyroid hormones help your blood flow
smoothly by relaxing the muscles of your blood vessels and
keeping your blood vessels open.
Hypothyroidism also can lead to increased levels of LDL (“bad”)
cholesterol, total cholesterol, triglycerides, and other fats related
to heart disease.
What serious problems can happen
if I have heart disease?
Rare but serious problems can include
• Heart failure (called congestive heart failure): when the heart
can’t pump enough blood for your body to work properly
• Heart attack: when a blood clot blocks the flow of blood in
your heart
• Stroke: when the blood vessels to the brain are blocked and
your brain doesn’t get enough blood
• Peripheral artery disease: when your legs don’t get enough
blood
• Sudden cardiac arrest: when your heart suddenly stops
working, you stop breathing, you pass out, and could die
unless resuscitated
You can also have a very slow heart rate and irregular heartbeats.
What kinds of heart-related
problems can happen with
hypothyroidism?
You can have
• Higher blood pressure
• Low heart rate (less than 60 beats a minute)
• Increased stiffness of walls of the blood vessels
• Increased strain on the heart
• Enlargement of the heart
Heart problems can even occur with mild hypothyroidism
(called subclinical hypothyroidism).
Editors
Alan Farwell, MD
James V. Hennessey, MD
Leonard Wartofsky, MD
December 2013
What can I do to take care of
heart-related problems?
Make sure you see your doctor regularly for checkups and checks
of your blood pressure. Get medical tests as recommended, such
as a blood test to check cholesterol levels. Ask your doctor if you
need medicines for heart problems. See a registered dietitian for
diet advice if needed.
What are my long-term prospects
with hypothyroidism?
Hypothyroidism is a lifelong condition, but taking thyroid hormone
pills every day can prevent related health problems, such as heart
problems. You should get a checkup at least once a year to make
sure your dose of thyroid hormone is still right for you.
Questions to ask your doctor
• Do I have hypothyroidism?
• What tests do I need? When?
• What are my options for treatment?
• How long will I need treatment?
• How often will I need checkups?
• Should I see an endocrinologist?
• Should I see a registered dietitian?
Resources
• Find-an-Endocrinologist: www.hormone.org or
call 1-800-HORMONE (1-800-467-6663)
• Find a registered dietitian (Academy of Nutrition and
Dietetics): http://eatright.org/programs/rdfinder/
• Hormone Health Network information about thyroid conditions:
www.hormone.org/diseases-and-conditions/thyroid
• Hormone Health Network information about medicines for
hypothyroidism: www.hormone.org/questions-and-answers/
2012/medicines-for-hypothyroidism
• American Thyroid Association information about
hypothyroidism: www.thyroid.org/what-is-hypothyroidism
• MedlinePlus (National Institutes of Health) information about
hypothyroidism: www.nlm.nih.gov/medlineplus/ency/article/
000353.htm
• Mayo Clinic information about hypothyroidism:
www.mayoclinic.com/health/hypothyroidism/DS00353/
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The Hormone Health Network offers free, online resources based
on the most advanced clinical and scientific knowledge from
The Endocrine Society (www.endocrine.org). The Network’s goal
is to move patients from educated to engaged, from informed to
active partners in their health care. This fact sheet is also available
in Spanish at www.hormone.org/audiences/pacientes-y-cuidadores.
Hypothyroidism and Heart Disease Fact Sheet
www.hormone.org