LKM1 Antibodies (Liver Kidney Microsomes)

Immunity

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Primarily used in the diagnosis of autoimmune hepatitis (AIH) type 2

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LKM1 Antibodies (Liver Kidney Microsomes) - Comprehensive Test Guide

Why is it done?
- Test Description: LKM1 antibody testing detects autoimmune antibodies directed against liver-kidney microsomal antigens, specifically the cytochrome P450 enzyme (CYP2D6). This test identifies autoimmune liver disease patterns.
- Primary Indications: Suspected autoimmune hepatitis (particularly Type 2 AIH), persistent elevated liver enzymes of unknown etiology, chronic liver inflammation without clear viral or alcoholic causes, investigation of progressive liver disease in children and young adults, and assessment of autoimmune liver disease patterns
- Typical Timing/Circumstances: Ordered when patients present with signs of chronic liver disease, abnormal liver function tests persisting beyond 6 months, symptoms suggestive of autoimmune hepatitis (fatigue, jaundice, abdominal discomfort), family history of autoimmune diseases, or when other causes of hepatitis have been excluded
Normal Range
- Reference Range: Negative or <1:40 (titer) in serum. Most laboratories report results as qualitative (positive/negative) or as titers ranging from <1:40 to ≥1:640
- Units of Measurement: Reported as titer (1:40, 1:80, 1:160, 1:320, 1:640) or presence/absence (positive/negative). Some laboratories use IU/mL (International Units per milliliter)
- Result Interpretation: Negative result = Antibodies not detected; suggests autoimmune hepatitis Type 2 is unlikely. Positive result = LKM1 antibodies present; consistent with Type 2 autoimmune hepatitis diagnosis. Higher titers generally correlate with more active disease but do not always predict severity
- What Normal vs Abnormal Means: Normal (negative) results indicate no evidence of LKM1 autoimmune antibodies, making Type 2 autoimmune hepatitis less likely. Abnormal (positive) results indicate the presence of autoimmune markers and strong suggestion of Type 2 AIH, particularly when combined with other autoimmune markers and clinical findings
Interpretation
- Negative Result (Absence of LKM1 Antibodies): Suggests Type 2 autoimmune hepatitis is unlikely; does not rule out Type 1 AIH (ANA/anti-smooth muscle positive); indicates alternative diagnoses should be pursued; requires correlation with clinical presentation and other antibody panels
- Positive Result (LKM1 Antibodies Present): Strongly indicative of Type 2 autoimmune hepatitis; may appear in other autoimmune liver diseases; requires confirmation with additional testing; clinical correlation with elevated transaminases and immunoglobulin levels is essential; positive results may persist despite treatment
- Titer Levels and Significance: 1:40-1:80 = Low positive; may be less clinically significant. 1:160-1:320 = Moderate positive; consistent with AIH diagnosis. ≥1:640 = High positive; strongly suggests active Type 2 AIH
- Factors Affecting Results: Immunosuppressive medications may suppress antibody levels; active hepatic inflammation increases antibody titers; concurrent infections may affect autoimmune responses; genetic predisposition influences antibody production; disease duration and stage affect antibody presence and levels
- Clinical Significance Patterns: Isolated LKM1 positivity with elevated ALT/AST = Highly suggestive Type 2 AIH. LKM1+ with ANA+ = Overlap syndrome possible. LKM1+ with anti-LC1+ = Confirms Type 2 AIH diagnosis. LKM1+ in asymptomatic patients = Requires monitoring; may progress to symptomatic disease
Associated Organs
- Primary Organs Involved: Liver = Primary target organ; experiences inflammation and hepatocyte damage. Kidneys = Secondary target; LKM1 antigens also present in renal tubular cells; may develop glomerulonephritis or tubulointerstitial nephritis
- Diseases Associated with Abnormal Results: Type 2 Autoimmune Hepatitis (AIH) = Most specific association; more common in children and young adults. Chronic Hepatitis C Infection = Can induce secondary LKM1 antibodies. Autoimmune Sclerosing Cholangitis = May present with LKM1 positivity. Overlap Autoimmune Liver Syndromes = Combined features of AIH and other autoimmune conditions
- Organ System Manifestations: Hepatic = Inflammation, fibrosis, cirrhosis, acute liver failure, portal hypertension. Renal = Glomerulonephritis, microscopic hematuria, proteinuria, progressive renal insufficiency. Extra-hepatic = Arthralgia, rash, thyroid disease, celiac disease
- Potential Complications with Abnormal Results: Cirrhosis development if untreated; hepatic decompensation; acute liver failure; hepatocellular carcinoma risk; portal hypertension; ascites; variceal bleeding; hepatic encephalopathy; chronic kidney disease; end-stage renal disease; increased infection risk; coagulopathy
Follow-up Tests
- Confirmatory Antibody Testing: Anti-LC1 (Liver Cytosol 1 antibodies) = Often coexists with LKM1; further confirms Type 2 AIH. ANA (Antinuclear Antibodies) = To rule out Type 1 AIH or overlap syndromes. Anti-SMA (Anti-Smooth Muscle Antibodies) = Evaluates Type 1 AIH features. Anti-Centromere and Anti-Mitochondrial Antibodies = Screens for primary biliary cirrhosis involvement
- Hepatic Function Assessment: ALT/AST = Markers of hepatocellular inflammation; baseline and serial measurements. Alkaline Phosphatase and GGT = Assess cholestasis component. Bilirubin (Total and Direct) = Evaluates liver synthetic function. Albumin and Prothrombin Time (PT/INR) = Assess liver synthetic capacity and prognosis
- Immunological Assessment: Immunoglobulin G (IgG) Levels = Elevated in autoimmune hepatitis; marker of disease activity. Total Immunoglobulin Panel = Assesses broader autoimmune activity
- Diagnostic Imaging and Biopsy: Liver Ultrasound or CT Scan = Assess liver architecture, cirrhosis features, portal hypertension signs. FibroScan (Transient Elastography) = Non-invasive assessment of liver fibrosis stage. Liver Biopsy = Gold standard for diagnosis; assesses inflammation grade and fibrosis stage; performed when diagnosis uncertain or prognosis needs clarification
- Viral Screening: Hepatitis A, B, C Serology = Excludes viral hepatitis; differentiates from HCV-induced secondary LKM1 antibodies. HIV Testing = Screens for immunocompromised status affecting autoimmune disease manifestation
- Renal Function Monitoring: Serum Creatinine and BUN = Assess baseline renal function. Urinalysis with Microscopy = Screen for hematuria and proteinuria. Estimated GFR (eGFR) = Calculate kidney filtration rate periodically
- Monitoring Frequency for Positive Results: Initial diagnosis phase = Monthly monitoring of liver enzymes and clinical status. During treatment = Every 3 months for first year; then every 6 months if stable. Long-term monitoring = Annually once remission achieved; more frequently if disease flares occur. LKM1 titer rechecking = Typically not repeated unless clinical status changes; primarily used at baseline diagnosis
Fasting Required?
- Fasting Status: No, fasting is NOT required for LKM1 antibody testing. This is a serological antibody test not affected by food intake.
- Patient Preparation Requirements: Standard venipuncture preparation = Patient may eat and drink normally prior to blood draw. Clothing = Wear loose-fitting sleeves to facilitate arm access. Hydration = Adequate hydration helpful for easier blood draw; drink water as normal. Timing = No specific time requirement; can be drawn any time of day
- Medications: Immunosuppressive medications = DO NOT discontinue; continue taking as prescribed; these medications do not invalidate test results, though they may lower antibody titers. All other medications = Continue as normal; no medications need to be held or avoided for this test. Supplements = No supplements require discontinuation; they do not interfere with antibody testing
- Special Instructions: Blood collection = Single venipuncture; tube must be properly labeled with patient identifiers. Specimen handling = Serum separator tube typically used; allow blood to clot at room temperature for 30 minutes minimum. Transport = Refrigerate or keep at room temperature per laboratory protocol. Testing method = Indirect immunofluorescence, ELISA, or chemiluminescence; determined by laboratory. Turnaround time = Typically 2-5 business days; may vary by laboratory. Emergency situations = May be expedited to same-day or next-day results in acute clinical settings

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