Also Known As
Liver Kidney Microsomal Type 1 Antibodies
LKM1 Antibodies
Anti-Liver/Kidney Microsomal Antibodies Type 1
Anti-P450 2D6 Antibody
Formal Name
Liver Kidney Microsome Type 1 Antibodies (Cytochrome P450 2D6 Antibodies)
This article was last reviewed on
This article waslast modified on January 5, 2021.
At a Glance
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 healthcare practitioner suspects may be due to an autoimmune-related process

Sample Required?

A blood sample drawn from a vein in your arm

Test Preparation Needed?


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The reference ranges for your tests can be found on your laboratory report. They are typically found to the right of your results.

If you do not have your lab report, consult your healthcare provider or the laboratory that performed the test(s) to obtain the reference range.

Laboratory test results are not meaningful by themselves. Their meaning comes from comparison to reference ranges. Reference ranges are the values expected for a healthy person. They are sometimes called "normal" values. By comparing your test results with reference values, you and your healthcare provider can see if any of your test results fall outside the range of expected values. Values that are outside expected ranges can provide clues to help identify possible conditions or diseases.

While accuracy of laboratory testing has significantly evolved over the past few decades, some lab-to-lab variability can occur due to differences in testing equipment, chemical reagents, and techniques. This is a reason why so few reference ranges are provided on this site. It is important to know that you must use the range supplied by the laboratory that performed your test to evaluate whether your results are "within normal limits."

For more information, please read the article Reference Ranges and What They Mean.

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 is general agreement that there are two main types of autoimmune hepatitis (debate continues as to whether there is a distinct third type). 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.

Accordion Title
Common Questions
  • 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 healthcare 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 signs and symptoms, such as fatigue, weakness, and jaundice, and has abnormal findings on routine liver tests.

    Signs and symptoms associated with autoimmune hepatitis may also include:

    • Itching
    • 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 signs and 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 the anti-LKM-1 test is negative, but SMA and/or ANA are positive, then the person likely has type 1 autoimmune hepatitis.

    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 that person's 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 antibody, sometimes referred to as anti-LKM3. This type of antibody is not detected with the usual anti-LKM-1 test methods and is not typically tested for.

    The ANA test is often performed along with an SMA test. It is a marker of an autoimmune process and is associated with several autoimmune disorders, including type 1 autoimmune hepatitis.

  • 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 healthcare practitioner 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 healthcare practitioner 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.

View Sources

Sources Used in Current Review

2017 review performed by Rose Romeo, PhD, DABCC, FACB.

Bogdanos, DP, Invernizzi, P, Mackay, IR and D vergani (2008). Autoimmune liver serology: Current diagnostic and clinical challenges. World Journal of Gastroenterology, vol 14: 3374-3387.

European Association for the Study of the Liver (EASL) Clinical Practice Guidelines: Autoimmune hepatitis (2015). Journal of Hepatology, vol 63: 971-1004.

Czaja, AJ (2016). Diagnosis and Management of Autoimmune Hepatitis: Current Status and Future Directions. Gut and Liver, vol 10: 177-203.

Narciso-Schiavon, JL and LL Schiavon (2017). To screen or not to screen? Celiac antibodies in liver diseases. World Journal of Gastroenterology, vol. 23: 776-791.

Himoto, T & M Nishioka (2013) Autoantibodies in liver disease: important clues for the diagnosis, disease activity and prognosis. Autoimmune Highlights. Vol 4: 39-53.

Wolf, D (2016). Medscape Article: Autoimmune hepatitis. Available online at Accessed April 28th, 2017.

ARUP. Liver-Kidney Microsome Antibody, IgG (2017). Available online at Accessed on April 29th 2017.

Sources Used in Previous Reviews

(Updated 2012 February 16). Autoimmune Hepatitis. National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) [On-line information]. Available online at Accessed August 2013.

Longstreth, G. (Updated 2012 October 8) Autoimmune hepatitis. MedlinePlus Medical Encyclopedia [On-line information]. Available online at Accessed August 2013.

Slev, P. and Tebo, A. (Updated 2013 February). Hepatitis, Autoimmune – AIH. ARUP Consult [On-line information]. Available online at Accessed August 2013.

((©) 1995 – 2013). Liver/Kidney Microsome Type 1 Antibodies, Serum. Mayo Clinic Mayo Medical Laboratories [On-line information]. Available online at Accessed August 2013

Wolf, D. and Raghuraman, U. (Updated 2013 July 29). Autoimmune Hepatitis. Medscape Reference [On-line information]. Available online at Accessed August 2013.

Shaffer, E. (Revised 2009 June). Laboratory Tests of the Liver and Gallbladder. Merck Manual for Healthcare Professionals [On-line information]. Available online through Accessed August 2013.

Mayo Clinic Staff (2012 April 18). Autoimmune hepatitis. [On-line information]. Available online at Accessed August 2013.

Mieli-Vergani, G. (2009 August). Autoimmune Hepatitis. J Pediatr Gastroenterol Nutr, v 49 (2) [On-line information]. Available online at Accessed August 2013.

Trivedi, P. and Hirschfield, G. (2012). Review Article: Overlap Syndromes and Autoimmune Liver Disease. Medscape Today News from Aliment Pharmacol Ther. 2012;36(6):517-533. [On-line information]. Available online at Accessed August 2013.

Stephen Kriese, S. and Heneghan, M. (2013). Current Concepts in the Diagnosis and Management of Autoimmune Hepatitis. Medscape Multispecialty from Frontline Gastroenterol. 2013;4(1):2-11. Accessed September 2013.

Clarke, W., Editor (© 2011). Contemporary Practice in Clinical Chemistry 2nd Edition: AACC Press, Washington, DC. Pp 314.

Wu, A. (© 2006). Tietz Clinical Guide to Laboratory Tests, 4th Edition: Saunders Elsevier, St. Louis, MO. Pp 682-683.

Henry's Clinical Diagnosis and Management by Laboratory Methods. 21st ed. McPherson R, Pincus M, eds. Philadelphia, PA: Saunders Elsevier: 2007, pg 951.

Tietz Textbook of Clinical Chemistry and Molecular Diagnostics. Burtis CA, Ashwood ER, Bruns DE, eds. 4th edition, St. Louis: Elsevier Saunders; 2006, pp 1812-1814.

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