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Test ID LKM Liver/Kidney Microsome Type 1 Antibodies, Serum

Reporting Name

Liver/Kidney Microsome Type 1 Ab, S

Useful For

Evaluation of patients with liver disease of unknown etiology


Evaluation of patients with suspected autoimmune hepatitis

Specimen Type


Specimen Required


Preferred: Serum gel

Acceptable: Red top

Specimen Volume: 0.5 mL

Specimen Minimum Volume

0.4 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Serum Refrigerated (preferred) 21 days
  Frozen  21 days

Reference Values

≤20.0 Units (negative)

20.1-24.9 Units (equivocal)

≥25.0 Units (positive)

Reference values apply to all ages.

Day(s) Performed

Monday, Wednesday, Friday

Test Classification

This test has been cleared, approved, or is exempt by the US Food and Drug Administration and is used per manufacturer's instructions. Performance characteristics were verified by Mayo Clinic in a manner consistent with CLIA requirements.

CPT Code Information


LOINC Code Information

Test ID Test Order Name Order LOINC Value
LKM Liver/Kidney Microsome Type 1 Ab, S 32220-6


Result ID Test Result Name Result LOINC Value
LKM Liver/Kidney Microsome Type 1 Ab, S 32220-6

Clinical Information

Autoimmune hepatitis (AIH) is a form of chronic liver disease that results from a loss of immune system tolerance and recognition of self-antigens.(1) AIH occurs in children and adults, with a significant female predominance. The clinical presentation of AIH varies significantly from asymptomatic liver dysfunction to acute liver failure. Evidence of liver dysfunction manifests as elevated aspartate aminotransferase, alanine aminotransferase, and gamma glutaryl transferase in the context of normal alkaline phosphatase. In addition, most individuals with AIH display increased concentrations of total IgG.


AIH is associated with the production of autoantibodies, which also serves to subcategorize patients.(2) AIH type I is characterized by the presence of antinuclear antibodies (ANA) and smooth muscle antibodies (SMA). AIH type I is associated with anti-liver/kidney microsomal-1 (LKM-1) and anti-liver cytosol-1 antibodies. AIH type I occurs in children and adults and usually has a relatively mild course that is responsive to steroids and azathioprine. In contrast, AIH type 2 occurs predominantly in children, with a more moderate/severe disease course.


Most of the autoantibodies associated with AIH were originally detected and characterized by indirect immunofluorescence (IIF).(3) Anti-LKM-1 antibodies can be detected by IIF using rodent stomach/liver/kidney composite tissue; anti-LKM-1 antibodies display staining of the proximal tubules in the kidney and cytoplasmic staining of the hepatocytes, with no reactivity on the stomach tissue. The antigen for anti-LKM-1 antibodies has been identified as cytochrome P450 2D6, which has led to the development of solid-phase and bead-based immunoassays.


Although not diagnostic in isolation, the various autoantibodies play an important part in establishing the diagnosis of AIH. Simplified diagnostic criteria for AIH include autoantibodies (ANA, SMA, anti-LKM-1, and anti-SLA), IgG concentrations, histopathology, and evaluation for viral hepatitis, with a scoring system to define probable or definite AIH.(4)


Seropositivity for anti-liver/kidney microsomal antibodies type 1 antibodies is consistent with a diagnosis of autoimmune hepatitis type 2, in patients with compatible clinical symptoms and histopathology.

Clinical Reference

1. Mieli-Vergani G, Vergani D, Czaja AJ, et al: Autoimmune hepatitis. Primer. 2018 Apr 12;4:18017. doi: 10.1038/nrdp.2018.17

2. Beretta-Piccoli BT, Mieli-Vergani G, Vergani D: Serology in autoimmune hepatitis: A clinical-practice approach. Eur J Intern Med. 2018 Feb;48:35-43. doi: 10.1016/j.ejim.2017.10.006

3. Liberal R, Mieli-Vergani G, Vergani D: Clinical significance of autoantibodies in autoimmune hepatitis. J Autoimmun. 2013 Oct;46:17-24. doi: 10.1016/j.jaut.2013.08.001

4. Hennes EM, Zeniya M, Czaja AJ, et. al: Simplified criteria for the diagnosis of autoimmune hepatitis. Hepatology. 2008 Jul;48(1):169-76. doi: 10.1002/hep.22322

Report Available

2 to 4 days

Method Name

Enzyme-Linked Immunosorbent Assay (ELISA)


If not ordering electronically, complete, print, and send a Gastroenterology and Hepatology Client Test Request (T728) with the specimen.