Hypothyroidism (underactive thyroid) is a condition characterized by abnormally low thyroid hormone production. When there is not enough thyroid hormone present, body processes begin to slow down resulting in low metabolism and less energy. Because thyroid hormone affects many cellular processes, it’s important to seek treatment since untreated hypothyroidism can lead to health problems, such as obesity, high cholesterol (heart disease), infertility, and depression.

Causes and Risk Factors of Hypothyroidism

The most common cause of hypothyroidism is Hashimoto’s thyroiditis – an autoimmune disorder that leads to chronic inflammation of the thyroid. Over time, this impairs the thyroid’s ability to produce thyroid hormones, leading to a gradual decline in function that eventually results in hypothyroidism. Other common causes of hypothyroidism include: radiation therapy to the neck, radioactive iodine treatment, thyroid surgery and certain medications.

Although anyone can develop hypothyroidism, women are more likely to develop hypothyroidism than men. Other risk factors include:

• Autoimmune diseases, such as Hashimoto’s, type 1 diabetes, rheumatoid arthritis, lupus, etc.

• A family history of thyroid disease

• Treatment with radioactive iodine, or anti-thyroid medications

• Radiation to the neck, or upper chest

• Thyroid surgery

• Being pregnant, or postpartum

If you have risk factors for hypothyroidism, speak with your physician about whether thyroid screening may be appropriate for you.

Symptoms of Hypothyroidism

Individuals in the early stages of hypothyroidism may be asymptomatic since hormone levels haven't decreased enough to have a noticeable impact on the metabolism. However, as thyroid function declines and the body’s metabolism continues to slow, individuals with hypothyroidism may develop noticeable symptoms.

The following are the most common symptoms associated with hypothyroidism:

• Fatigue

• Weight gain or difficulty losing weight

• Dry hair and dry skin

• Hair loss

• Increased sensitivity to cold

• Constipation

• Depression

• Impaired memory

• Abnormal menstrual cycles

• Muscle weakness, aches or stiffness

• Joint pain, stiffness or swelling

• Elevated blood cholesterol level

• Slowed heart rate

• Swelling of the thyroid gland (goiter)

If you have symptoms of hypothyroidism, it’s important to speak to your physician about thyroid screening. In addition, if you've had previous thyroid surgery, treatment with radioactive iodine or anti-thyroid medications, or received radiation therapy to the neck area, it’s important to see your physician for periodic testing to monitor your thyroid function since you’re at increased risk for developing hypothyroidism during your lifetime.

Diagnosing Hypothyroidism

If you have symptoms of hypothyroidism, your physician will start the diagnostic process by reviewing your medical and family history, risk factors, and performing a physical examination to check your thyroid gland. In addition, your physician will screen for hypothyroid signs and symptoms, such as dry skin, enlarged thyroid gland, slower reflexes, and a slower heart rate.

Your physician will order blood work to check thyroid hormone levels. These tests may include:

TSH (thyroid-stimulating hormone) test – The most definitive test for hypothyroidism is the TSH (thyroid-stimulating hormone) test. An abnormally high TSH indicates hypothyroidism, since the pituitary gland will produce more TSH in an effort to stimulate the thyroid gland to produce more thyroid hormone. In addition to diagnosing hypothyroidism, TSH tests are also used to help physicians determine the right dosage of thyroid medication for treating the condition, both initially and over time.

T4 (thyroxine) tests – Your physician may also order free T4 tests to aid in the diagnosis. The free T4, in combination with a TSH test, can help your physician determine how your thyroid is functioning. Lower-than-normal T4 levels usually indicate hypothyroidism. However, some individuals may have increased TSH levels while having normal T4 levels. This is called subclinical (mild) hypothyroidism, which is an early stage of hypothyroidism.

Anti-thyroid antibody tests – Since thyroid antibodies are found in most cases of Hashimoto’s, your physician may order anti-thyroid antibodies tests, such as the thyroid peroxidase antibodies (TPO Ab). These antibodies may appear decades before a change in TSH is detected.

If your blood tests, or physical exam of your thyroid, are abnormal, your physician may also order a Thyroid Ultrasound to check for thyroid nodules or inflammation to further aid in the diagnosis.

At Hoag, our multidisciplinary team of thyroid care experts are highly skilled in the diagnosis and treatment of thyroid disease.

Treatment Options for Hypothyroidism

Standard treatment for hypothyroidism involves daily use of the synthetic thyroid hormone levothyroxine, which is highly effective when prescribed properly. This medication helps to normalize thyroid stimulating hormone levels, allowing individuals to gain relief from symptoms and live a normal life.

Since thyroid hormone replacement therapy is a very individualized treatment process, your physician will regularly check your TSH level to determine the right dosage of thyroid hormone both initially and throughout your lifetime. By taking your medication daily, and seeking regular follow-up care with your physician, you should be able to keep your hypothyroidism well controlled throughout your lifetime.

Because certain medications can interfere with how your body absorbs synthetic thyroid hormone, it’s important to speak with your physician about all of the medications, herbs, and supplements you take, including over-the-counter products.