What this test measures
The Liver Kidney Microsomes (LKM) test detects autoantibodies — most commonly anti-LKM-1 — directed against cytochrome P450 2D6 (CYP2D6), an enzyme expressed in liver and kidney microsomal membranes. These antibodies are a hallmark of autoimmune hepatitis type 2 (AIH-2), a less common but more aggressive form of autoimmune liver disease that mostly affects children and young women.
LKM antibodies are also seen, at lower titres, in chronic hepatitis C (anti-LKM-1), some drug-induced liver injuries (halothane, anti-epileptics — anti-LKM-2), and chronic hepatitis D (anti-LKM-3). The test is reported as a titre (e.g., 1:40, 1:80, 1:160) or as units/mL by ELISA.
Why it matters
Autoimmune hepatitis is under-recognised in India — it presents at any age, often as unexplained chronic transaminitis or as an acute hepatitis that does not match viral serology. Type 2 (LKM-positive) is rarer than type 1 (ANA / SMA-positive) but tends to be more aggressive, with rapid progression to cirrhosis if untreated. Early diagnosis matters because immunosuppressive therapy (steroids + azathioprine) can induce long-term remission.
The LKM test is part of a standard autoimmune hepatitis panel ordered when SGPT/SGOT remain raised after viral, alcoholic and metabolic causes have been excluded, especially in children, young women, and patients with overlap features of autoimmune disease.
How to prepare
No fasting required. Continue regular medications. Mention any recent hepatitis vaccinations, autoimmune diseases, family history of autoimmune disease, and all medications including herbal preparations.
Markers & reference ranges
Reference ranges below are typical adult values. Your lab's reported range may differ slightly based on the assay platform and patient demographics — always read your report against the range printed on it.
| Marker | Normal range | If low | If high |
|---|---|---|---|
| Anti-LKM-1 Antibody (Titre or U/mL)[1][2] | Negative or titre < 1:40 (method-dependent) | A negative or low-titre result essentially rules out autoimmune hepatitis type 2 but does not rule out type 1 (ANA / SMA positive). | Positive — strongly supports autoimmune hepatitis type 2, especially with high titre (>1:80) plus raised SGPT/SGOT, raised IgG, and a compatible liver biopsy. Lower titres can be seen in chronic hepatitis C, some drug-induced hepatitis (halothane, tienilic acid), and autoimmune polyglandular syndrome type 1. |
Autoantibody patterns in autoimmune hepatitis
| Type | Characteristic antibodies | Typical patient | Behaviour |
|---|---|---|---|
| AIH Type 1 | ANA, Anti-Smooth Muscle (SMA), Anti-SLA | Adults, women > men, any age | Most common; responds well to steroids + azathioprine |
| AIH Type 2 | Anti-LKM-1, Anti-LC1 | Children and young women | Less common; more aggressive; needs prompt immunosuppression |
| Drug-induced (LKM-2) | Anti-LKM-2 (tienilic acid, halothane) | Drug exposure | Resolves on stopping drug |
| Chronic hepatitis C with LKM | Anti-LKM-1 (low titre) | Adults with HCV | Manage HCV; check if true AIH |
Frequently asked questions
Who needs an LKM antibody test?
Anyone with unexplained chronic raised liver enzymes after viral hepatitis, alcohol, drug and metabolic causes have been excluded — especially children, young women, or patients with other autoimmune disease.
Do I need to fast?
No fasting is required for this test.
My LKM is negative — does that rule out autoimmune hepatitis?
It rules out type 2 (LKM-positive) but not type 1 (which is much more common and is ANA / SMA positive). A complete autoimmune hepatitis panel includes ANA, SMA, anti-LKM-1, anti-SLA, and total IgG.
Can chronic hepatitis C give a positive LKM?
Yes — about 5% of chronic HCV patients have low-titre anti-LKM-1 antibodies without true autoimmune hepatitis. Distinguishing them clinically (clinical pattern, IgG level, biopsy) is important because steroids can worsen viral hepatitis.
Is autoimmune hepatitis curable?
It is usually a chronic condition, but standard immunosuppression (steroids + azathioprine) induces remission in 70–80% of patients. Many can be maintained on low-dose therapy for years; some achieve durable drug-free remission after careful taper.
Are family members at risk?
There is a modest familial / genetic predisposition (HLA associations), and autoimmune diseases tend to cluster in families. Routine screening of relatives is not currently recommended, but symptomatic relatives should be evaluated promptly.
Related Liver / Enzymes tests
Tests commonly ordered alongside LIVER KIDNEY MICROSOMES, or that help interpret an unexpected result.
Sources & references
- AASLD Practice Guidance — Autoimmune Hepatitis (2019) · accessed 2026-05-30T00:00:00.000Z
- NCBI StatPearls — Autoimmune Hepatitis · accessed 2026-05-30T00:00:00.000Z
- Mayo Clinic Laboratories — Liver/Kidney Microsomal Antibodies · accessed 2026-05-30T00:00:00.000Z
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