Anti smooth muscle antibody (ASMA) Test

Your doctor may recommend an ASMA test if they suspect a liver condition, such as hepatitis or cirrhosis. The test is typically ordered when the liver function tests report abnormal values. If a doctor has already ruled out excessive alcohol consumption, viral infection, drugs, toxins, genetic conditions and metabolic disorders as a cause of liver disease, then he/she might suspect an autoimmune process. Conditions which cause liver damage can trigger the body to produce antibodies against smooth muscle. Some other antibodies which could be indicative of autoimmune hepatitis are: 

• Anti-nuclear antibodies
• Anti-soluble liver antigen/liver pancreas (anti-SLA/LP) antibodies
• Anti-actin antibodies 

ASMA test is a simple blood test. You do not require any special preparation before this test. Please inform the doctor if you are taking any medicines or supplements. Your doctor or nurse will explain the purpose of the test and the procedure involved. Speak to your doctor if you have any concerns regarding the test.

A laboratory technician or nurse will collect a blood sample for the test. They will first tie a tourniquet around your upper arm to locate a vein. Then, using a sterile needle, they will withdraw about 7 mL of blood from the vein. The blood sample will be transferred to a tube with a red top and sent to a laboratory for testing. 

You may experience a stinging pain when the needle is inserted; however, it won’t last too long. If you experience excessive bruising or bleeding at the site of needle insertion, please consult your doctor.

Normal results:

Normal results in the ASMA test are generally reported as negative. It could mean that there are no antibodies against smooth muscle in your blood, or the value found was probably below the cut off value to be reported as positive. 

Absence of ASMA does not confirm that a person is free of autoimmune liver disease. It has been observed that some people with autoimmune hepatitis may show the presence of other autoantibodies, but not ASMA.

Abnormal results:

Abnormal results in the ASMA test are reported as positive. Some testing facilities may also give a numerical value relating to the number of antibodies found. However, this value varies greatly from one laboratory to the other. Your doctor will be able to explain what exactly your test result means.

Presence of ASMA could be indicative of the following conditions:

• Type 1 autoimmune chronic active hepatitis
• Autoimmune hepatitis/primary biliary cirrhosis overlap
• Cryptogenic cirrhosis

Sometimes, the test can also show positive results in the following conditions:

• Acute viral hepatitis
• Yellow fever
• Asthma
• Malignant tumours
• Infectious mononucleosis
• Rheumatoid arthritis 
• Multiple sclerosis

Since the test is not found to be positive in case of systemic lupus erythematosus (SLE), it is useful in distinguishing other autoimmune conditions from SLE. In the rarest cases, the antibodies may be produced in the body in the absence of any underlying condition. 

Disclaimer: All results must be clinically correlated with the patient’s complaints to make a complete and accurate diagnosis. The above information is provided from a purely educational point of view and is in no way a substitute for medical advice by a qualified doctor.