The thyroid is a butterfly-shaped gland in the middle of the neck, located below the larynx (voice box) and above the clavicles (collarbones). The thyroid produce two hormones, triiodothyronine (T3) and thyroxine (T4), which regulate how the body uses and stores energy (also known as the body's metabolism).
Thyroid function is controlled by a gland in the brain, known as the pituitary. The pituitary produces thyroid-stimulating hormone (TSH), which stimulates the thyroid to produce T3 and T4.
Hypothyroidism is the medical term for when a person does not make enough thyroid hormone.
There is a gland in your neck called the thyroid gland. It makes thyroid hormone. This hormone controls how the body uses and stores energy. Hypothyroidism is the medical term for when a person does not make enough thyroid hormone.
In about 95 percent of cases, hypothyroidism is due to a problem in the thyroid gland itself and is called primary hypothyroidism. However, certain medications and diseases can also decrease thyroid function. As an example, hypothyroidism can also develop after medical treatments for hyperthyroidism, such as thyroidectomy (surgical removal of the thyroid) or radioactive iodine treatment (to destroy thyroid tissue).
In some cases, hypothyroidism is a result of decreased production of thyroid-stimulating hormone (TSH) by the pituitary gland (called secondary hypothyroidism). Thyroid problems are more common in women, increase with age, and are more common in whites and Mexican Americans than in blacks.
General symptoms : Thyroid hormone normally stimulates the metabolism, and most of the symptoms of hypothyroidism reflect slowing of metabolic processes. General symptoms may include fatigue, sluggishness, weight gain, and intolerance of cold temperatures.
Skin : Hypothyroidism can decrease sweating. The skin may become dry and thick. The hair may become coarse or thin, eyebrows may disappear, and nails may become brittle.
Eyes : Hypothyroidism can lead to mild swelling around the eyes. People who develop hypothyroidism after treatment for Graves' disease may retain some of the eye symptoms of Graves' disease, including protrusion of the eyes, the appearance of staring, and impaired movement of the eyes.
Cardiovascular system :Hypothyroidism slows the heart rate and weakens the heart's contractions, decreasing its overall function. Related symptoms may include fatigue and shortness of breath with exercise. These symptoms may be more severe in people who also have heart disease. In addition, hypothyroidism can cause mild high blood pressure and raise blood levels of cholesterol.
Respiratory system :Hypothyroidism weakens the respiratory muscles and decreases lung function. Hypothyroidism can also lead to swelling of the tongue, hoarse voice, and sleep apnea.
Gastrointestinal system :Hypothyroidism slows the actions of the digestive tract, causing constipation. Rarely, the digestive tract may stop moving entirely.
Reproductive system :Women with hypothyroidism often have menstrual cycle irregularities, ranging from absent or infrequent periods to very frequent and heavy periods. The menstrual irregularities can make it difficult to become pregnant, and pregnant women with hypothyroidism have an increased risk for miscarriage during early pregnancy.
The treatment for hypothyroidism is thyroid hormone replacement therapy. This is usually given as an oral form of T4 (levothyroxine). T4 should be taken once per day on an empty stomach (ideally one hour before eating or two hours after; most patients take their hormone as soon as they wake in the morning, and delay eating breakfast as long as practical before leaving for work or school).
Thyroid hormone pills come in different brand name and generic forms. All the pills work equally well. But you should not switch from one generic or brand name to another. Switching between pills can cause your levels to go up and down.
In most cases, symptoms of hypothyroidism begin to improve within two weeks of starting thyroid replacement therapy. However, people with more severe symptoms may require several months of treatment before they fully recover.
What if I want to get pregnant?
Many women with hypothyroidism have healthy pregnancies. But your doctor will most likely need to change your dose of thyroid hormone once you are pregnant. That's because you need more thyroid hormone during pregnancy. He or she will also measure your levels of thyroid hormone 4 weeks after any change in your dose, and at least once during each trimester of pregnancy.
Hypothyroidism without symptoms - In some cases, hypothyroidism is extremely mild or causes no obvious symptoms (called subclinical hypothyroidism). Many experts treat patients with subclinical hypothyroidism if their TSH is >7 to 10 mU/L to prevent the development of hypothyroidism and associated symptoms. Treatment is also recommended for people who have a goiter or nonspecific symptoms of hypothyroidism, such as fatigue, constipation, or depression.