Smooth Muscle Antibody

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Também chamado: SMA; Anti-Smooth Muscle Antibody; ASMA; F-Actin Antibody; ACTA
Nome formal: Smooth Muscle Antibody

De relance

Por que fazer este exame?

To help diagnose chronic active autoimmune hepatitis and distinguish it from other causes of liver injury

Quando fazer este exame?

When a patient has hepatitis that the doctor suspects may be due to an autoimmune-related process

Amostra:

A blood sample drawn from a vein in your arm

É necessária alguma preparação?

None

A amostra

O que está sendo pesquisado?

This test measures the amount of smooth muscle antibodies (SMA) in the blood. SMA are proteins produced by the body’s immune system that are directed against its own cytoskeletal proteins of the smooth muscle. Cytoskeletal proteins form the framework within a cell that serve to support or reinforce the cell structure. The production of SMA is strongly associated with chronic active autoimmune hepatitis but may also be seen in other forms of liver disease and with other autoimmune disorders such as primary biliary cirrhosis, but usually at lower titers. Autoimmune hepatitis presents as an acute or chronic inflammation of the liver that is not a result of another discernable cause – such as a viral infection, drug, toxin, hereditary disorder, or alcohol abuse. It can lead to liver cirrhosis and, in some cases, to liver failure.

Autoimmune hepatitis can be found in anyone at any age, but about 80% of those affected are women. In the United States, more than 70% of patients with this disorder will have SMA, either alone or along with ANA (antinuclear antibodies). F-actin is a specific cytoskeletal protein whereby autoantibodies directed against it may be increased. Some recent studies suggest that it is a more specific test than SMA in diagnosing autoimmune liver disease, with about 52% to 85% of those affected having the F-actin autoantibody.

Como a amostra é obtida para o exame?

A blood sample is obtained by inserting a needle into a vein in the arm.

NOTA: Se exames médicos em você ou em alguém importante para você o deixam ansioso ou constrangido, ou se você tem dificuldade de lidar com eles, leia um ou mais dos seguintes artigos: Lidando com dor, desconforto ou ansiedade durante o exame, Conselhos sobre exames de sangue, Conselhos para ajudar crianças durante exames médicos, and Conselhos para ajudar idosos durante exames médicos.

Outro artigo, Siga essa amostra, fornece uma visão da coleta e do processamento de uma amostra de sangue e de uma amostra de cultura da garganta.

É necessário algum preparo para garantir a qualidade da amostra?

No test preparation is needed.

O exame

Perguntas frequentes

Pergunte ao laboratório

* indica um campo necessário



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Fontes do artigo

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NOTA: Este artigo se baseia em pesquisas que incluíram as fontes citadas e a experiência coletiva de Lab Tests Online Conselho de Revisão Editorial. Este artigo é submetido a revisões periódicas do Conselho Editorial, e pode ser atualizado como resultado dessas revisões. Novas fontes citadas serão adicionadas à lista e distinguidas das fontes originais usadas.

Sources Used in Current Review

Pagana, Kathleen D. & Pagana, Timothy J. (© 2007). Mosby’s Diagnostic and Laboratory Test Reference 8th Edition: Mosby, Inc., Saint Louis, MO. Pp 96-97.

Clarke, W. and Dufour, D. R., Editors (© 2006). Contemporary Practice in Clinical Chemistry: AACC Press, Washington, DC. Pp 272.

Wu, A. (© 2006). Tietz Clinical Guide to Laboratory Tests, Fourth Edition: Saunders Elsevier, St. Louis, MO. Pp 990-991.

Lee, S. (Updated 2007 May 27). Anti-smooth muscle antibody. MedlinePlus Medical Encyclopedia [On-line information]. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/003531.htm. Accessed 1/29/09.

(2008 April). Autoimmune Hepatitis. NDDIC [On-line information]. Available online at http://digestive.niddk.nih.gov/ddiseases/pubs/autoimmunehep/ through http://digestive.niddk.nig.gov. Accessed 1/29/09.

Dugdale, D. (Updated 2008 November 2). Autoimmune liver disease panel. MedlinePlus Medical Encyclopedia [On-line information]. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/003328.htm. Accessed 1/29/09.

Hill, H. et. al (Updated 2008 September). Hepatitis, Autoimmune – AIH. ARUP Consult [On-line information]. Available online at http://www.arupconsult.com/Topics/GastrointestinalDz/AIH.html# through http://www.arupconsult.com. Accessed 1/29/09.

Sources Used in Previous Reviews

Thomas, Clayton L., Editor (1997). Taber’s Cyclopedic Medical Dictionary. F.A. Davis Company, Philadelphia, PA [18th Edition].

Pagana, Kathleen D. & Pagana, Timothy J. (2001). Mosby’s Diagnostic and Laboratory Test Reference 5th Edition: Mosby, Inc., Saint Louis, MO. Pp 92-93.

Beuers, U. and Rust, C. (2005 October 27). Overlap Syndromes. Medscape, from Semin Liver Dis. 2005; 25(3): 311-320. [On-line information]. Available online at http://www.medscape.com/viewarticle/512463 through http://www.medscape.com.

Stone, C. (2004 November 10, Updated). Autoimmune liver disease panel. Medline Plus Medical Encyclopedia [On-line information]. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/003328.htm.

Peng, S. (2005 April 20). Anti-smooth muscle antibody. Medline Plus Medical Encyclopedia [On-line information]. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/003531.htm.

(© 2005). Smooth Muscle Antibody, IgG with Reflex to Titer. ARUP's Guide to Clinical Laboratory Testing [On-line information]. Available online at http://www.arup-lab.com/guides/clt/tests/clt_203b.jsp#3219875 through http://www.arup-lab.com.

Strassburg, C. and Manns, M. (2003 January 9). Autoantibodies and Autoantigens in Autoimmune Hepatitis. Medscape from Semin Liver Dis 22(4): 339 -351, 2002 [On-line journal]. Available online at http://www.medscape.com/viewarticle/445619 through http://www.medscape.com.

Czaja, A. and Freese, D. et. al. (2002 August). Diagnosis and treatment of autoimmune hepatitis. National Guideline Clearinghouse [On-line information]. Available online through http://www.guideline.gov.

(© 2005). F-Actin (Smooth Muscle) IgG by Enzyme. ImmunoassayARUP's Guide to Clinical Laboratory Testing [[On-line information]. Available online at http://www.aruplab.com/guides/clt/tests/clt_a254.jsp#5444091 through http://www.aruplab.com.

(© 2003). Actin (Smooth Muscle) Antibody. LabCorp [On-line test information]. Available online at http://www.labcorp.com/datasets/labcorp/html/chapter/mono/se018700.htm through http://www.labcorp.com.