The thyroid gland is an important organ of the endocrine system. It is located at the front of the neck, just above where your collarbones meet. The thyroid makes hormones that control the way every cell in the body uses energy. This process is called metabolism.
Hypothyroidism is more common in women and people over age 50.
The most common cause of hypothyroidism is thyroiditis. Swelling and inflammation damage the thyroid gland's cells.
Causes of this problem include:
The immune system attacking the thyroid gland
Viral infections (common cold) or other respiratory infections
Pregnancy (often called postpartum thyroiditis)
Other causes of hypothyroidism include:
Certain medicines, such as lithium and amiodarone, and some types of chemotherapy
Congenital (birth) defects
Radiation treatments to the neck or brain to treat different cancers
Radioactive iodine used to treat an overactive thyroid gland
Surgical removal of part or all of the thyroid gland
Sheehan syndrome, a condition that may occur in a woman who bleeds severely during pregnancy or childbirth and causes the destruction of the pituitary gland
Pituitary tumor or pituitary surgery
What are the symptoms for Hypothyroidism?
Hard stools or constipation
Feeling cold (wearing a sweater when others are wearing a t-shirt)
Fatigue or feeling slowed down
Heavier and irregular menstrual periods
Joint or muscle pain
Paleness or dry skin
Sadness or depression
Thin, brittle hair or fingernails
Late symptoms, if untreated:
Decreased taste and smell
Puffy face, hands, and feet
Thickening of the skin
Thinning of eyebrows
Low body temperature
Slow heart rate
What are the current treatments for Hypothyroidism?
Treatment is aimed at replacing the thyroid hormone you are lacking.
Levothyroxine is the most commonly used medicine:
You will be prescribed the lowest dose possible that relieves your symptoms and brings your blood hormone levels back to normal.
If you have heart disease or you are older, your provider may start you on a very small dose.
Most people with an underactive thyroid will need to take this medicine for life.
Levothyroxine is usually a pill, but some people with very severe hypothyroidism first need to be treated in the hospital with intravenous levothyroxine (given through a vein).
When starting you on your medicine, your provider may check your hormone levels every 2 to 3 months. After that, your thyroid hormone levels should be monitored at least once every year.
When you are taking thyroid medicine, be aware of the following:
Do not stop taking the medicine, even when you feel better. Continue taking it exactly as your provider prescribed.
If you change brands of thyroid medicine, let your provider know. Your levels may need to be checked.
What you eat can change the way your body absorbs thyroid medicine. Talk with your provider if you are eating a lot of soy products or are on a high-fiber diet.
Thyroid medicine works best on an empty stomach and when taken 1 hour before any other medicines. Ask your provider if you should take your medicine at bedtime. Taking it at bedtime may allow your body to absorb the medicine better than taking it in the daytime.
Wait at least 4 hours after taking thyroid hormone before you take fiber supplements, calcium, iron, multivitamins, aluminum hydroxide antacids, colestipol, or medicines that bind bile acids.
While you are taking thyroid replacement therapy, tell your provider if you have any symptoms that suggest your dose is too high, such as:
Rapid weight loss
Restlessness or shakiness (tremors)
What is the outlook (prognosis) for Hypothyroidism?
In most cases, thyroid hormone level becomes normal with proper treatment. You will likely take a thyroid hormone medicine for the rest of your life.
What are the possible complications for Hypothyroidism?
Myxedema crisis (also called myxedema coma), the most severe form of hypothyroidism, is rare. It occurs when thyroid hormone levels get very, very low. The severe hypothyroid crisis is then caused by an infection, illness, exposure to cold, or certain medicines (opiates are a common cause) in people with severe hypothyroidism.
Myxedema crisis is a medical emergency that must be treated in the hospital. Some people may need oxygen, breathing assistance (ventilator), fluid replacement, and intensive-care nursing.
Symptoms and signs of myxedema coma include:
Below normal body temperature
Low systolic blood pressure
Low blood sugar
Inappropriate or uncharacteristic moods
People with untreated hypothyroidism are at increased risk of:
Infertility, miscarriage, giving birth to a baby with birth defects
Heart disease because of higher levels of LDL (bad) cholesterol
When should I contact a medical professional for Hypothyroidism?
Call your provider if you have symptoms of hypothyroidism.
If you are being treated for hypothyroidism, call your provider if:
You develop chest pain or rapid heartbeat
You have an infection
Your symptoms get worse or do not improve with treatment
You develop new symptoms
Brent GA, Weetman AP. Hypothyroidism and thyroiditis. In: Melmed S, Auchus RJ, Goldfine AB, Koenig RJ, Rosen CJ, eds. Williams Textbook of Endocrinology. 14th ed. Philadelphia, PA: Elsevier; 2020:chap 13.
Garber JR, Cobin RH, Gharib H, et al. Clinical practice guidelines for hypothyroidism in adults: cosponsored by the American Association of Clinical Endocrinologists and the American Thyroid Association. Endocr Pract. 2012;18(6):988-1028. PMID: 23246686 pubmed.ncbi.nlm.nih.gov/23246686/.
Jonklaas J, Bianco AC, Bauer AJ, et al; American Thyroid Association Task Force on Thyroid Hormone Replacement. Guidelines for the treatment of hypothyroidism: prepared by the American Thyroid Association task force on thyroid hormone replacement. Thyroid. 2014;24(12):1670-1751. PMID: 25266247 pubmed.ncbi.nlm.nih.gov/25266247/.