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Hypothyroidism - Highlights

Description

An in-depth report on the causes, diagnosis, treatment, and prevention of hypothyroidism.

Alternative Names

Autoimmune thyroiditis; Hashimoto's thyroiditis

Highlights:

What is Hypothyroidism?

Hypothyroidism, also called underactive thyroid, is a condition in which the thyroid gland does not produce enough hormone. Hypothyroidism can be caused by the autoimmune disorder Hashimoto� ' s thyroiditis, irradiation or surgical removal of the thyroid gland, and medications that reduce thyroid hormone levels. Anyone can develop hypothyroidism, but people who are most at risk include those who are over age 50 and female. However, only a small percentage of people have full-blown (overt) hypothyroidism. Many more have mildly underactive glands (subclinical hypothyroidism).

Symptoms

Early symptoms of hypothyroidism include:

Chronic fatigue
Difficulty concentrating
Sensitivity to cold
Headache
Muscle and joint aches
Weight gain, despite diminished appetite
Constipation
Dry skin
Early puberty
Menstrual irregularities (either heavier-than-normal or lighter-than-normal bleeding)
Milky discharge from the breasts (galactorrhea)

Diagnosis and Treatment

Hypothyroidism can cause serious complications if left untreated. Fortunately, it can be easily diagnosed with blood tests that measure levels of the thyroid hormone thyroxine (T4) and thyroid-stimulating hormone (TSH). The doctor may also want to test for antithyroid antibodies and check your cholesterol levels. Based on these test results, the doctor will decide whether to prescribe medication or simply have the patient get lab tests every 6 - 12 months.

Medications

The standard drug treatment for hypothyroidism is a daily dose of a synthetic thyroid hormone called levothyroxine. This drug helps normalize blood levels of T4, TSH, and a third hormone called triidothyronine(T3). Many prescription medications can interact with levothyroxine and either increase or decrease its potency. (Make sure your doctor knows all medications you are taking.) Large amounts of dietary fiber can also interfere with levothyroxine treatment. People who eat high-fiber diets may require higher doses of the drug.

Resources

www.aace.com -- American Association of Clinical Endocrinologists
www.thyroid.org -- American Thyroid Association
www.hormone.org -- Hormone Foundation
www.endo-society.org -- Endocrine Society

References

Abalovich M, Amino N, Barbour LA, Cobin RH, De Groot LJ, Glinoer D, et al. Management of thyroid dysfunction during pregnancy and postpartum: an Endocrine Society Clinical Practice Guideline. J Clin Endocrinol Metab. 2007 Aug;92(8 Suppl):S1-47.

Allahabadia A, Razvi S, Abraham P, Franklyn J. Diagnosis and treatment of primary hypothyroidism. BMJ. 2009 Mar 26;338:b725. doi: 10.1136/bmj.b725.

American Academy of Pediatrics, Rose SR; Section on Endocrinology and Committee on Genetics, American Thyroid Association, Brown RS; Public Health Committee, et al. Update of newborn screening and therapy for congenital hypothyroidism. Pediatrics. 2006 Jun;117(6):2290-303.

Brent GA, Larsen PR, Davies TF. Hypothyroidism and thyroiditis. In: Kronenberg: HM, Shlomo M, Polonsky KR, Larsen PR, eds. Williams Textbook of Endocrinology. 11th ed. Philadelphia, Pa: Saunders Elsevier; 2008:chap 12.

Fatourechi V. Subclinical hypothyroidism: an update for primary care physicians. Mayo Clin Proc. 2009;84(1):65-71.

Gyamfi C, Wapner RJ, D'Alton ME. Thyroid dysfunction in pregnancy: the basic science and clinical evidence surrounding the controversy in management. Obstet Gynecol. 2009 Mar;113(3):702-7.

Kliegman RM. Hypothyroidism. In: Kliegman RM, Behrman RE, Jenson HB, Stanton BF, eds. Nelson Textbook of Pediatrics. 18th ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 566.

Mestman JH. Thyroid and parathyroid diseases in pregnancy. In: Gabbe SG, Niebyl JR, Simpson JL, eds. Obstetrics: Normal and Problem Pregnancies. 5th ed.Philadelphia, Pa: Elsevier Churchill Livingstone; 2007:chap 38.

Ochs N, Auer R, Bauer DC, Nanchen D, Gussekloo J, Cornuz J, Rodondi N. Meta-analysis: subclinical thyroid dysfunction and the risk for coronary heart disease and mortality. Ann Intern Med. 2008 Jun 3;148(11):832-45. Epub 2008 May 19.

Roberts LM, Pattison H, Roalfe A, Franklyn J, Wilson S, Hobbs FD, et al. Is subclinical thyroid dysfunction in the elderly associated with depression or cognitive dysfunction? Ann Intern Med. 2006 Oct 17;145(8):573-81.

Rodondi N, Aujesky D, Vittinghoff E, Cornuz J, Bauer DC. Subclinical hypothyroidism and the risk of coronary heart disease: a meta-analysis. Am J Med. 2006 Jul;119(7):541-51.

Stagnaro-Green A. Maternal thyroid disease and preterm delivery. J Clin Endocrinol Metab. 2009 Jan;94(1):21-5. Epub 2008 Nov 4.

Vaidya B, Pearce SH. Management of hypothyroidism in adults. BMJ. 2008 Jul 28;337:a801. doi: 10.1136/bmj.a801.

Villar HC, Saconato H, Valente O, Atallah AN. Thyroid hormone replacement for subclinical hypothyroidism. Cochrane Database Syst Rev. 2007 Jul 18;(3):CD003419.

Reviewed last on: 5/21/2009
Harvey Simon, MD, Editor-in-Chief, Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital.Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

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