Hypothyroidism
It is a condition in which the thyroid gland does not produce enough thyroid hormone.
Causes
The thyroid gland, located in the front of the neck just below the laryn, secretes hormones that control metabolism.
Hypothyroidism, or underactive thyroid, is more common in women and people over 50 years.
The most common cause of hypothyroidism is thyroiditis. The swelling and inflammation damage cells of the thyroid gland. The causes of this problem include:
- An attack on the thyroid gland by the immune system.
- Cold or other respiratory infection.
- Pregnancy (often called postpartum thyroiditis).
Other causes of hypothyroidism include:
- Certain medications, such as lithium or amiodarone.
- Congenital (at birth) abnormalities.
- Radiation treatments to the neck or brain to treat various cancers.
- Radioactive iodine used to treat an overactive thyroid.
- Surgical removal of part or all of the thyroid gland.
- Sheehan syndrome, a condition that can occur in a woman who bleeds severely during pregnancy or childbirth, and causes destruction of the pituitary.
Symptoms
Early symptoms:
- Hard stools or constipation.
- Increased sensitivity to cold.
- Fatigue or feeling sluggish .
- Heavy periods .
- Muscle or joint pain .
- Pale or dry skin.
- Sadness or depression.
- Brittle hair or nails.
- Weakness .
- Weight gain (unintentional) .
Late symptoms, if left untreated:
- Decreased sense of taste and smell.
- Hoarseness.
- Swelling of the face, hands and feet.
- Slow speech.
- Thickening of the skin.
- Thinning of eyebrows.
Exams and Tests
A physical examination may reveal the presence of a smaller thyroid gland than normally, although, sometimes the gland is normal or even enlarged size. The exam may also reveal:
- Brittle nails.
- Coarse facial features .
- Pale or dry skin may be cool to the touch .
- Swelling of arms and legs.
- Thin and brittle hair .
Some of the lab tests to determine thyroid function include:
- Examination of thyroid stimulating hormone (TSH).
- T4 test.
Other tests that may be done:
- Cholesterol levels.
- Complete blood count (CBC) .
- Liver enzymes.
- Prolactin.
- Sodium.
Treatment
The purpose of treatment is to replace the thyroid hormone that is lacking. Levothyroxine is the drug used most frequently.
- Doctors will prescribe the lowest dose possible to relieve symptoms and to bring hormone levels in the blood back to normal.
- If you have heart disease or greater, the doctor may start giving you a very small dose.
- Most people with an underactive thyroid need lifelong therapy.
When you start taking the medication, your doctor can check hormone levels every 2 or 3 months. After that, the thyroid hormone levels should be monitored at least annually.
The important things to remember when you are taking thyroid hormone are:
- Do not stop taking the medication when you feel better. Keep taking it exactly as the doctor ordered.
- If you change the brand of thyroid medicine, let your doctor know. You may need to take control levels.
- What you eat can change the way the body absorbs the thyroid medicine. Talk to your doctor if you are consuming a lot of soy products or a diet rich in fiber.
- The thyroid medication works best on an empty stomach and when taken an hour before any other medications.
- Do not take thyroid hormone with fiber supplements, calcium, iron, multivitamins, aluminum hydroxide antacids, colestipol, or medicines that bind bile acids.
While you are taking thyroid replacement therapy, tell your doctor if you have any symptoms that suggest that your dose is too high, such as:
- Palpitations.
- Rapid weight loss.
- Restlessness or tremor.
- Sweating.
Myxedema coma is a medical emergency that occurs when the level of thyroid hormone in the body becomes extremely low, and is treated with thyroid hormone replacement therapy by intravenous and steroid medications. Some patients may need supportive therapy (oxygen, breathing assistance, fluid replacement) and intensive care nursing. If it is not treated in time, the patient may die.
Forecast
In most cases, thyroid levels return to normal with proper treatment. However, you must take thyroid hormone replacement therapy for the rest of life.
Complications
Myxedema coma, the most severe form of hypothyroidism, is rare and can be caused by infection, illness, exposure to cold, or certain medications in people who have not been treated for hypothyroidism.
Symptoms and signs of myxedema coma include:
- Temperature below normal.
- Decreased respiration.
- Low blood pressure.
- Low blood sugar .
- Lack of reaction or response .
Other complications include:
- Disease.
- Increased risk of infection.
- Infertility.
- Spontaneous abortion.
People with untreated hypothyroidism are at increased risk of:
- Giving birth to a baby with birth defects.
- Disease due to higher levels of LDL ("bad").
- Heart failure.
People treated with too much thyroid hormone are at risk for angina or heart attacks, as well as osteoporosis (thinning of the bones).
Complications
Call your doctor if you have symptoms of hypothyroidism (or myxedema).
If you are being treated for hypothyroidism, call your doctor if:
- You develop chest pain or fast heartbeat.
- You have an infection.
- The symptoms worsen or do not improve with treatment.
- New symptoms.
Prevention
There is no prevention for hypothyroidism.
With screening of newborns, this can be identified at birth (congenital hypothyroidism) hypothyroidism.
Alternative Names
Hypothyroidism in adults; Myxedema.
References
Brent GA, Davies TF. Hypothyroidism and thyroiditis. In: Melmed S, Polonsky KS, Larsen PR, Kronenberg HM, et al. Williams Textbook of Endocrinology. 12th ed. Philadelphia, Pa: Saunders Elsevier, 2011: chap 13.
Kim M, Ladenson P. Thyroid. In: Goldman L, Schafer AI, eds. Cecil Medicine. 24th ed. Philadelphia, Pa: Saunders Elsevier, 2011: chap 233.
Updated: 4/6/2012
Version Reviewed By: David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine. Also reviewed by Shehzad Topiwala, MD, Chief Consultant Endocrinologist, Premier Medical Associates, The Villages, FL. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, ADAM Health Solutions, Ebix, Inc.
Translation and Localization by ADAM Logo
Taken from: http://www.nlm.nih.gov/medlineplus/spanish/ency/article/000353.htm