What Is Hypothyroidism?
The thyroid gland is located in the neck.
Hypothyroidism, or underactive thyroid, is a common endocrine disorder that occurs when a person does not produce enough thyroid hormone. The thyroid gland, located in the neck, makes thyroid hormone that controls how the body uses and stores energy. When you lack adequate thyroid hormone, you feel tired.
A form of hypothyroidism is autoimmune thyroid disease, called Hashimoto’s disease or Hashimoto’s thyroiditis. Myxedema coma is a severe form of hypothyroidism.
The opposite of hypothyroidism is hyperthyroidism, a condition that occurs when the body produces too much thyroid hormone.
What Are Signs and Symptoms of Hypothyroidism?
Symptoms of hypothyroidism may be subtle such as slowed mental or physical activity, and some people may have no symptoms.
Common symptoms and signs of hypothyroidism may include the following:
Signs and symptoms of hypothyroidism can show up in the hands and nails. Hypothyroidism can cause dermatologic findings such as nail infection, vertical white ridges on the nails, nail splitting, brittle nails, slow nail growth, and nails lifting up.
Other signs and symptoms of hypothyroidism may include the following:
- Slowed speech and movements
- Yellowing skin and eyes (jaundice)
- Pale skin (pallor)
- Coarse, brittle, straw-like hair
- Dull facial expression
- Coarse facial features
- Swelling around the eyes
- Enlarged tongue
- Goiter (simple or nodular)
- Decreased systolic blood pressure (upper number) and increased diastolic blood pressure (lower number)
- Slow heart rate
- Excess fluid around the heart (pericardial effusion)
- Abdominal distention, fluid in the abdominal cavity (ascites) (uncommon)
- Pitting edema of lower extremities
- Below normal reflexes with delayed relaxation, loss of coordination, or both
Symptoms that are more specific to Hashimoto thyroiditis include
- feeling of fullness in the throat;
- painless thyroid enlargement;
- exhaustion; and
- temporary neck pain, sore throat, or both.
Symptoms of myxedema coma (severe hypothyroidism) include the following:
- Altered mental status
- Slow heart rate
- Too much carbon dioxide (CO2) in the bloodstream
- Low blood sodium levels
- Enlarged heart, fluid around the heart, cardiogenic shock, and ascites
- Nonpitting edema
What Causes Hypothyroidism?
In the U.S. and other countries where iodine intake is adequate, the most common cause of hypothyroidism is autoimmune thyroid disease (Hashimoto’s disease).
Worldwide, iodine deficiency is the main cause.
How Do Doctors Diagnose Hypothyroidism?
In addition to a history and physical examination, doctors need to perform blood tests to diagnose hypothyroidism.
The main blood tests used to diagnose hypothyroidism include
- thyroid-stimulating hormone (TSH) and
- thyroxine (T4).
Additional testing may be done that includes
- triiodothyronine (T3) and
- thyroid antibody tests.
What Is the Treatment for Hypothyroidism?
Thyroid hormone replacement therapy treats hypothyroidism. Doctors usually prescribe levothyroxine (LT4) (Synthroid, Levoxyl, Levothroid, Unithyroid).
In some cases, doctors may give another form of thyroid hormone, liothyronine (T3) (Cytomel, Triostat), with T4. However, since T4 is converted into triiodothyronine (T3) in other organs, most studies have not shown an advantage of combining T3 and T4 over using T4 alone.
Women may need higher doses of T4 during pregnancy.
What Are Complications of Hypothyroidism?
Hypothyroidism in pregnancy can result in the following obstetric complications:
Hypothyroidism may cause complications in patients with certain mental illness:
- Patients with depression may develop mania.
- Psychosis may worsen in patients with severe psychiatric illness.
If not treated promptly, hypothyroidism in infants can cause the following complications:
- Irreversible mental retardation
- Slowed physical and linear bone growth
- Delayed dental development
What Is the Life Expectancy for Hypothyroidism?
In most cases, proper treatment with thyroid replacement therapy can reverse signs and symptoms of hypothyroidism and patients can live a normal life span.
If hypothyroidism is not adequately treated, the disease can progress and lead to profound coma or even death.
Reviewed on 5/15/2020
American Academy of Dermatology. “THYROID DISEASE: A CHECKLIST OF SKIN, HAIR, AND NAIL CHANGES.” .
Orlander, Philip R. “Hypothyroidism.” Medscape.com. Nov. 5, 2019. <http://emedicine.medscape.com/article/122393-overview>.