Also known as:Liver Kidney Microsomal Type 1 Antibodies; LKM1 Antibodies; Anti-Liver/Kidney Microsomal Antibodies Type 1; Anti-LKM1; Anti-P450 2D6 Antibody
Formal name:Liver Kidney Microsome Type 1 Antibodies (Cytochrome P450 2D6 Antibodies)
Related tests:Smooth Muscle Antibody, AMA, ANA, Autoantibodies, AST, Bilirubin
Why Get Tested?
To help diagnose autoimmune hepatitis and distinguish it from other causes of liver injury
When to Get Tested?
When you have hepatitis that your health practitioner suspects may be due to an autoimmune-related process
A blood sample drawn from a vein in your arm
Test Preparation Needed?
How is it used?
The liver kidney microsome type 1 antibody (anti-LKM-1 or CYP2D6 antibody) test is primarily used along with a smooth muscle antibody (SMA) and an antinuclear antibodies (ANA) test to help diagnose autoimmune hepatitis and to differentiate between the two major types, type 1 and type 2.
These tests may be used to follow up abnormal liver test findings, such as persistently increased alanine aminotransferase (ALT), aspartate aminotransferase (AST), or bilirubin. Additional tests may be ordered, such as immunoglobulins, as these may be increased with autoimmune hepatitis and/or hepatitis B and/or hepatitis C, to rule out viral hepatitis.
When is it ordered?
The anti-LKM-1 test may be ordered when a health practitioner is investigating an individual's liver disease and wants to distinguish between different causes of liver injury. It may be ordered along with other testing, such as an SMA and ANA test. These tests are usually ordered when a person presents with symptoms such as fatigue, weakness, and jaundice and has abnormal findings on routine liver tests.
Symptoms associated with autoimmune hepatitis may also include:
- An enlarged liver
- Joint aches
- Abdominal discomfort
- Abnormal blood vessels in the skin (spider angiomas)
- Nausea or vomiting
- Dark urine
- Loss of appetite
- Pale or clay-colored stools
- Muscle pain (myalgia)
- In women, lack of menstrual periods (amenorrhea)
- Skin rashes
- Fluid buildup (edema)
Many of these symptoms are not specific for autoimmune hepatitis; they are also seen with other causes of liver injury and with other conditions.
What does the test result mean?
A high amount or titer of anti-LKM-1 indicates that it is likely that the person tested has type 2 autoimmune hepatitis, but the result is not definitive. A liver biopsy may be performed to evaluate liver tissue for damage and scarring to help confirm the diagnosis.
If both are negative, then the person's symptoms are likely due to a cause other than autoimmune hepatitis. However, the condition is not entirely ruled out. Not all people with autoimmune hepatitis will produce anti-LKM-1 or SMA antibodies; some people produce other autoantibodies that are rarely tested.
Is there anything else I should know?
Levels of anti-LKM-1 are not closely related to the severity of a person's symptoms or to their prognosis. Levels may vary over time.
Those with type 2 autoimmune hepatitis may also have other autoimmune disorders, such as diabetes or thyroiditis.
People with chronic hepatitis C may sometimes develop a different type of anti-LKM-1 antibody. This type of antibody is not detected with the usual anti-LKM-1 test methods and is not typically tested for.
What is being tested?
Liver kidney microsome type 1 (anti-LKM-1) antibodies are autoantibodies, proteins produced by the body's immune system that recognize and target its own enzyme called cytochrome P450 2D6 (CYP2D6), a protein found primarily in liver cells. The development of anti-LKM-1 antibodies is strongly associated with type 2 autoimmune hepatitis. This test detects and measures the amount (titer) of anti-LKM-1 (or antibody against CYP2D6) in the blood.
Autoimmune hepatitis is an acute or chronic inflammation of the liver that can lead to liver cirrhosis and, in some cases, to liver failure. It is hepatitis that is not due to another identifiable cause, such as a viral infection, exposure to a drug or toxin, a hereditary disorder, or alcohol abuse. Anyone can develop the disorder, but the majority of those affected are women.
There are two main types of autoimmune hepatitis. Type 1 is the most common form of autoimmune hepatitis in the United States and is associated with the presence of smooth muscle antibodies (SMA) in the blood. Type 2 is less common and tends to be more severe. It is associated with anti-LKM-1 antibodies and primarily affects young girls and is more common in Europe than in the United States.
How is the sample collected for testing?
A blood sample is obtained by inserting a needle into a vein in the arm.
NOTE: If undergoing medical tests makes you or someone you care for anxious, embarrassed, or even difficult to manage, you might consider reading one or more of the following articles: Coping with Test Pain, Discomfort, and Anxiety, Tips on Blood Testing, Tips to Help Children through Their Medical Tests, and Tips to Help the Elderly through Their Medical Tests.
Another article, Follow That Sample, provides a glimpse at the collection and processing of a blood sample and throat culture.
Is any test preparation needed to ensure the quality of the sample?
No test preparation is needed.
- Should everyone with liver damage be tested for liver kidney microsome type 1 antibodies (anti-LKM-1)?
This is not usually necessary. Most cases of hepatitis will be due to another identifiable cause. However, if the person with symptoms is a young girl without other risk factors, and/or the doctor suspects an autoimmune process, then anti-LKM-1, ANA, and SMA testing may be performed.
- Will anti-LKM-1 ever go away?
No. Levels may vary over time, but once the autoantibodies have developed, they will be present throughout a person's life.
- Can I have more than one cause of hepatitis?
Yes. For instance, autoimmune hepatitis can co-exist with a viral hepatitis, such as hepatitis B or hepatitis C, and can become worse with liver damage caused by alcohol abuse. Since the treatment of hepatitis depends on the cause, it is very important that your doctor understand the underlying cause(s) of your condition.
- How fast does autoimmune hepatitis progress?
The course and severity of autoimmune hepatitis is hard to predict. It may be acute or chronic. Some people will have no or few symptoms for many years and are diagnosed when routine liver tests are abnormal. Those with type 2 autoimmune hepatitis often have a more severe case, but it is usually manageable with proper treatment. Appropriate treatment is important to limit liver damage. For more information, consult with your healthcare provider and see the related links.
- If this antibody targets CYP450 2D6, why is it called anti-liver kidney microsome-1 (anti-LKM-1)?
This antibody was originally detected using tissue from the liver and kidney, hence the name anti-LKM-1. However, the specific protein in those tissues that the antibody targets (the major antigen) has since been identified as cytochrome P450 2D6 (CYP2D6). This protein is a major enzyme that metabolizes about 25% of drugs as well as toxic substances. It is primarily found in cells of the liver and kidney, mainly within structures called microsomes.
© 2017 American Association for Clinical Chemistry, republished from Lab Tests Online.*
Descriptions of clinical laboratory tests were originally prepared for use on Lab Tests Online, an award-winning patient education website on clinical laboratory testing. Lab Tests Online is produced by the American Association for Clinical Chemistry (AACC), a global scientific and medical professional organization dedicated to clinical laboratory science and its application to healthcare. The Lab Tests Online website is developed in collaboration with other laboratory professional societies and is funded in part through corporate sponsorships.