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Antimitochondrial antibody testing is commonly used to aid in the diagnosis of primary biliary cirrhosis (PBC). How is the AMA-M2 test understood? The following article tells us more about this test.
1. What is AMA-M2?
AMA-M2 is an ELISA-based, automated, in-vitro assay system for the quantitative determination of IgG antibodies against mitochondrial M2 sub-antigens in human serum or plasma.
Anti-mitochondrial antibodies (AMA) are a heterogeneous group of autoantibodies against various proteins of the outer and inner mitochondrial membranes. The M2 subtype autoantibodies bind to the E2 subunits of the pyruvate dehydrogenase complex (PDC-E2), branched chain complex-2-oxoacid dehydrogenase (BCOADC-E2) and the 2-oxoglutarate-dehydrogenase complex E (OGDC-E2) . AMA-M2 is very sensitive and specific. They represent a serological marker of primary biliary cirrhosis. In addition to early detection and differential diagnosis, identification of the AMA structure allows for immunological classification and prognosis of primary biliary cirrhosis. In patients with other autoimmune diseases, especially collagenose disease, detection of AMA-M2 may help detect developing or associated primary biliary cirrhosis.
Viêm đường mật nguyên phát
Antibody antibodies (AMA) are autoantibodies closely related to primary biliary cholangitis (PBC), formerly known as primary biliary cirrhosis. This test detects and measures the amount (titer) of AMA in the blood. Primary cholangitis is a chronic autoimmune disorder that causes inflammation and scarring of the bile ducts inside the liver. This is a slowly progressive disease that causes the liver to deteriorate.
2. What is the purpose of the AMA-M2 test?
The AMA or AMA-M2 test is ordered when a doctor suspects that someone has an autoimmune disorder like PBC that is affecting the liver.
A person may have symptoms including: Itching, jaundice, fatigue, hepatomegaly, pain in the right upper abdomen, swelling or edema of the hands and feet, fluid accumulation in the abdomen, dry mouth and eyes, weight loss
Many of those with early primary cholangitis do not have any symptoms. The condition is usually identified initially because a person has abnormal results on the liver panel (elevated liver enzymes), especially alkaline phosphatase (ALP).
The AMA or AMA-M2 test may be ordered with or following a variety of tests used to help diagnose or rule out other causes of liver disease or injury. These causes can include infections, such as viral hepatitis, drugs, alcohol abuse, toxins, genetic conditions, metabolic conditions, and autoimmune hepatitis.
3. What should you know when performing an anti-mitochondrial antibody test?
The AMA or AMA-M2 test may be done along with many other tests used to rule out other causes of liver disease or injury. These causes include infections, such as viral hepatitis, drugs, alcohol abuse, toxins, genetic diseases, metabolic diseases, and autoimmune hepatitis.
The AMA and AMA-2 tests alone cannot definitively diagnose primary cholestatic cirrhosis, but combined with other tests and clinical symptoms, can diagnose primary cholestatic cirrhosis.
Other tests your doctor may order include:
Antinuclear antibodies (ANA). Immunoglobulin M (IgM). Bilirubin . Albumin. Anti-smooth muscle antibody (SMA).
Sinh thiết gan giúp chẩn đoán xơ gan mật nguyên phát sau khi có kết quả xét nghiệm dương tính AMA
The doctor needs to do an additional liver biopsy to confirm the diagnosis of primary biliary cirrhosis after a positive test result for AMA, and the results of quantification of liver enzymes are high.
Approximately 50% of cases of primary cholestatic cirrhosis will be detected before the patient has obvious symptoms.
4. Meaning of the AMA-M2 . test
More than 90% of patients with primary biliary cirrhosis (PBC) can detect anti-antibody (AMA) by indirect immunofluorescence, which also detects AMA in other features in other diseases. The AMA-recognized mitochondrial antigens in the patients' serum were numerically graded from M1 to M9, with the AMA-recognized M2 antigen complex in the serum of PBC patients. The M2 antigen consists of the enzyme proteins of the 2-oxoacid dehydrogenase complex located on the inner mitochondrial membrane. Included in this group of autoantigens are the pyruvate dehydrogenase complex, and the 2-oxoglutarate dehydrogenase complex.
AMA and AMA-M2 by themselves are not diagnostic of primary cholangitis, but in combination with other laboratory tests and clinical symptoms, PBC can be diagnosed. A liver biopsy may be performed to look for characteristic signs of PBC in liver tissue and to confirm the diagnosis, but is not always necessary. Liver imaging may also be ordered to look for bile duct obstructions. About 50% of cases of primary cholangitis will be detected before a person has noticeable symptoms.
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Normal result: No presence of anti-mitochondrial antibodies at titres >1:5 or antibody levels <0.1 units.
Abnormal results: Increased antibody levels:
Primary biliary cirrhosis (PBC). Chronic active hepatitis. Systemic lupus erythematosus. Syphilis. Drug-induced biliary obstruction. Autoimmune hepatitis. Extrahepatic obstruction. Acute infectious hepatitis. Vinmec International General Hospital is one of the hospitals that not only ensures professional quality with a team of leading doctors, modern equipment and technology, but also stands out for its examination and consulting services. and comprehensive, professional medical treatment; civilized, polite, safe and sterile medical examination and treatment space. Customers when choosing to perform tests here can be completely assured of the accuracy of test results.
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