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KembaraXtra-Medicine – Autoimmune Hepatitis
Autoimmune hepatitis (AIH) is an immune-mediated inflammatory liver disease marked by elevated serum gamma globulins (especially IgG), characteristic circulating autoantibodies, and typical biopsy findings of interface hepatitis with plasma cell–rich inflammation, after other causes of hepatitis have been excluded. There are two main types. Type 1 AIH is the most common worldwide (about 90%) and can occur at any age; it is often associated with antinuclear antibodies (ANA) and/or smooth muscle antibodies (SMA), and sometimes anti–soluble liver antigen (anti-SLA) or anti–liver-pancreas (anti-LP) antibodies. Type 2 AIH is less common (up to 10%), mainly affects children and young adolescents, and is typically associated with anti-LKM-1 or anti-LC1 antibodies, while ANA and SMA are usually absent; it often presents more acutely and may be harder to treat, with frequent relapse requiring long-term maintenance therapy.
AIH is more common in females and can occur across all ethnicities and age groups. In the United States, prevalence is estimated around 31 per 100,000 people, and globally incidence is roughly 0.9 to 2 cases per 100,000 people per year, with prevalence estimates ranging widely. Type 1 AIH has a bimodal peak (around puberty and again in mid-to-late adulthood), while type 2 is more common from ages 2 to 14. AIH accounts for a small but important portion of liver transplants in the U.S. (about 4% to 6%).
The exact cause is unknown, but AIH is thought to result from genetic susceptibility plus an environmental trigger. A leading theory involves a T-cell–mediated immune attack on hepatocytes, possibly related to reduced or dysfunctional regulatory T cells; humoral immunity also appears involved given the range of autoantibodies. Proposed triggers include viral infections (hepatitis A, B, C) and medications (such as minocycline, nitrofurantoin, biologics, and TNF inhibitors). Certain HLA haplotypes are associated with increased risk, including HLA-DR3 and DR4 in type 1 AIH and HLA-DR3 and DR7 in type 2.
Clinical presentation is broad, ranging from asymptomatic liver enzyme elevations to cirrhosis or fulminant liver failure. Symptoms may include fatigue, anorexia, nausea, abdominal pain, pruritus, and arthralgias. Some patients have other autoimmune features such as arthritis, dry mouth, eye irritation (keratoconjunctivitis), vasculitis, or erythema nodosum. Advanced disease can present with hepatosplenomegaly, ascites, peripheral edema, easy bruising/bleeding, and jaundice.
Diagnosis is based on a combination of laboratory evidence of liver injury, elevated IgG or hypergammaglobulinemia, characteristic autoantibodies, and compatible liver histology, while excluding other causes of hepatitis. Both major liver societies (EASL and AASLD) require a liver biopsy to establish diagnosis. Histology is suggestive rather than pathognomonic, with findings such as lymphoplasmacytic infiltrates crossing the limiting plate (interface hepatitis), periportal inflammation/necrosis, rosetting of hepatocytes, and emperipolesis. If cholestatic features are present, primary biliary cholangitis and primary sclerosing cholangitis should be evaluated; MRCP is recommended in adults with cholestatic lab changes and in all children with AIH, with ERCP considered if MRCP is nondiagnostic.
Workup includes history and exam (including screening for other autoimmune diseases), liver function tests and serum gamma globulins/IgG, and autoantibody testing (ANA, SMA/ASMA, anti-LKM, anti-SLA/LP). Aminotransferases are usually elevated (often ALT > AST) and may fluctuate; bilirubin and alkaline phosphatase may be normal or moderately elevated. IgG is elevated in about 90% of patients. Ultrasound is commonly used to rule out obstruction or mass, and MRCP is used when cholestasis suggests overlap disease. Patients with AIH-related cirrhosis should undergo hepatocellular carcinoma surveillance (typically ultrasound and AFP every 6 months).
Treatment includes avoiding alcohol and hepatotoxic medications, and considering liver transplantation for fulminant liver failure or end-stage disease. Steroids are the cornerstone: prednisone/prednisolone is commonly started at 0.5 to 1 mg/kg/day (often up to 60 mg/day) for induction. Azathioprine can be started at the same time or about 2 weeks later (often beginning at 50 mg/day and titrating up to 1 to 2 mg/kg/day depending on response and toxicity). In noncirrhotic AIH, budesonide (6 to 9 mg/day) plus azathioprine can be used to induce and maintain remission with fewer systemic steroid side effects; budesonide should not be used in cirrhosis due to reduced first-pass metabolism and increased systemic effects. Steroids may be avoided or used cautiously in brittle diabetes, uncontrolled hypertension, severe osteopenia, psychosis, or prior severe intolerance, while azathioprine is contraindicated in TPMT deficiency and significant cytopenias. Alternatives for azathioprine intolerance include 6-mercaptopurine and mycophenolate mofetil, and other second-line options (e.g., calcineurin inhibitors, sirolimus/everolimus, rituximab, infliximab) have been used in select refractory cases.
Treatment response is monitored with symptoms and normalization of liver tests, but biopsy activity can lag behind lab improvement by up to 6 months. Because relapse is common after withdrawal (often requiring long-term maintenance therapy), repeat biopsy is often considered before stopping therapy. Persistent interface hepatitis on biopsy is associated with very high relapse risk, and multiple relapses are linked with a higher chance of cirrhosis, so repeated attempts at withdrawal are generally discouraged. Acute severe AIH should be treated early with high-dose corticosteroids, and if there is no improvement within about 7 days, urgent transplant evaluation is recommended; acute liver failure presentations should be evaluated directly for transplantation.
Long-term outlook is generally good with treatment: many patients achieve remission within 18 months to 3 years, but a minority do not respond to standard therapy. Patients with decompensated cirrhosis, acute liver failure, hepatocellular carcinoma, or progression despite therapy should be referred for liver transplant evaluation.
Autoimmune hepatitis (AIH) is an immune-mediated inflammatory liver disease marked by elevated serum gamma globulins (especially IgG), characteristic circulating autoantibodies, and typical biopsy findings of interface hepatitis with plasma cell–rich inflammation, after other causes of hepatitis have been excluded. There are two main types. Type 1 AIH is the most common worldwide (about 90%) and can occur at any age; it is often associated with antinuclear antibodies (ANA) and/or smooth muscle antibodies (SMA), and sometimes anti–soluble liver antigen (anti-SLA) or anti–liver-pancreas (anti-LP) antibodies. Type 2 AIH is less common (up to 10%), mainly affects children and young adolescents, and is typically associated with anti-LKM-1 or anti-LC1 antibodies, while ANA and SMA are usually absent; it often presents more acutely and may be harder to treat, with frequent relapse requiring long-term maintenance therapy.
AIH is more common in females and can occur across all ethnicities and age groups. In the United States, prevalence is estimated around 31 per 100,000 people, and globally incidence is roughly 0.9 to 2 cases per 100,000 people per year, with prevalence estimates ranging widely. Type 1 AIH has a bimodal peak (around puberty and again in mid-to-late adulthood), while type 2 is more common from ages 2 to 14. AIH accounts for a small but important portion of liver transplants in the U.S. (about 4% to 6%).
The exact cause is unknown, but AIH is thought to result from genetic susceptibility plus an environmental trigger. A leading theory involves a T-cell–mediated immune attack on hepatocytes, possibly related to reduced or dysfunctional regulatory T cells; humoral immunity also appears involved given the range of autoantibodies. Proposed triggers include viral infections (hepatitis A, B, C) and medications (such as minocycline, nitrofurantoin, biologics, and TNF inhibitors). Certain HLA haplotypes are associated with increased risk, including HLA-DR3 and DR4 in type 1 AIH and HLA-DR3 and DR7 in type 2.
Clinical presentation is broad, ranging from asymptomatic liver enzyme elevations to cirrhosis or fulminant liver failure. Symptoms may include fatigue, anorexia, nausea, abdominal pain, pruritus, and arthralgias. Some patients have other autoimmune features such as arthritis, dry mouth, eye irritation (keratoconjunctivitis), vasculitis, or erythema nodosum. Advanced disease can present with hepatosplenomegaly, ascites, peripheral edema, easy bruising/bleeding, and jaundice.
Diagnosis is based on a combination of laboratory evidence of liver injury, elevated IgG or hypergammaglobulinemia, characteristic autoantibodies, and compatible liver histology, while excluding other causes of hepatitis. Both major liver societies (EASL and AASLD) require a liver biopsy to establish diagnosis. Histology is suggestive rather than pathognomonic, with findings such as lymphoplasmacytic infiltrates crossing the limiting plate (interface hepatitis), periportal inflammation/necrosis, rosetting of hepatocytes, and emperipolesis. If cholestatic features are present, primary biliary cholangitis and primary sclerosing cholangitis should be evaluated; MRCP is recommended in adults with cholestatic lab changes and in all children with AIH, with ERCP considered if MRCP is nondiagnostic.
Workup includes history and exam (including screening for other autoimmune diseases), liver function tests and serum gamma globulins/IgG, and autoantibody testing (ANA, SMA/ASMA, anti-LKM, anti-SLA/LP). Aminotransferases are usually elevated (often ALT > AST) and may fluctuate; bilirubin and alkaline phosphatase may be normal or moderately elevated. IgG is elevated in about 90% of patients. Ultrasound is commonly used to rule out obstruction or mass, and MRCP is used when cholestasis suggests overlap disease. Patients with AIH-related cirrhosis should undergo hepatocellular carcinoma surveillance (typically ultrasound and AFP every 6 months).
Treatment includes avoiding alcohol and hepatotoxic medications, and considering liver transplantation for fulminant liver failure or end-stage disease. Steroids are the cornerstone: prednisone/prednisolone is commonly started at 0.5 to 1 mg/kg/day (often up to 60 mg/day) for induction. Azathioprine can be started at the same time or about 2 weeks later (often beginning at 50 mg/day and titrating up to 1 to 2 mg/kg/day depending on response and toxicity). In noncirrhotic AIH, budesonide (6 to 9 mg/day) plus azathioprine can be used to induce and maintain remission with fewer systemic steroid side effects; budesonide should not be used in cirrhosis due to reduced first-pass metabolism and increased systemic effects. Steroids may be avoided or used cautiously in brittle diabetes, uncontrolled hypertension, severe osteopenia, psychosis, or prior severe intolerance, while azathioprine is contraindicated in TPMT deficiency and significant cytopenias. Alternatives for azathioprine intolerance include 6-mercaptopurine and mycophenolate mofetil, and other second-line options (e.g., calcineurin inhibitors, sirolimus/everolimus, rituximab, infliximab) have been used in select refractory cases.
Treatment response is monitored with symptoms and normalization of liver tests, but biopsy activity can lag behind lab improvement by up to 6 months. Because relapse is common after withdrawal (often requiring long-term maintenance therapy), repeat biopsy is often considered before stopping therapy. Persistent interface hepatitis on biopsy is associated with very high relapse risk, and multiple relapses are linked with a higher chance of cirrhosis, so repeated attempts at withdrawal are generally discouraged. Acute severe AIH should be treated early with high-dose corticosteroids, and if there is no improvement within about 7 days, urgent transplant evaluation is recommended; acute liver failure presentations should be evaluated directly for transplantation.
Long-term outlook is generally good with treatment: many patients achieve remission within 18 months to 3 years, but a minority do not respond to standard therapy. Patients with decompensated cirrhosis, acute liver failure, hepatocellular carcinoma, or progression despite therapy should be referred for liver transplant evaluation.
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