Autoimmune hepatitis overview

# Overview
Autoimmune hepatitis (AH) was first described in the 1950s and has had a variety of names including chronic active hepatitis, lupoid hepatitis, plasma cell hepatitis and autoimmune chronic active hepatitis.  It is characterized by circulating autoantibodies and a high serum globulin level. It is important to distinguish AH from other forms of liver disease, as a large percentage of patients respond to therapy and therapy has been shown to delay transplantation, improve the quality of life as well as prolong survival. Lupoid hepatitis (also called Autoimmune hepatitis) is an auto-immune disease which causes liver cirrhosis. It may be associated with systemic lupus erythematosus (SLE), or other connective tissue disorders. Around 60% of patients have chronic hepatitis that may mimic viral hepatitis, but without serologic evidence of a viral infection. The disease usually affects women and is strongly associated with anti-smooth muscle auto-antibodies. Autoimmune hepatitis is a condition in which the patient's own immune systems attacks the liver causing inflammation and liver cell death. The condition is chronic and progressive. Although the disease is chronic, many patients with autoimmune hepatitis present acutely ill with jaundice, fever and sometimes symptoms of severe hepatic dysfunction, a picture that resembles acute hepatitis. Autoimmune hepatitis usually occurs in women (70 %) between the ages of 15 and 40. Patients usually present with evidence of moderate to severe hepatitis with elevated serum ALT and AST activities in the setting of normal to marginally elevated alkaline phosphatase and gamma-glutamyltranspeptidase activities. The patient will sometimes present with jaundice, fever, and right upper quadrant pain and occasionally systemic symptoms such as arthralgias, myalgias, polyserositis and thrombocytopenia. Some patients will present with mild liver dysfunction and have only laboratory abnormalities as their initial presentation. Others will present with severe hepatic dysfunction. Mainstay treatment of autoimmune hepatitis is pharmacotherapy. Corticosteroids alone or in combination with immunosuppressants are commonly used. Liver transplantation is indicated when medical therapy fails, decompensated chronic liver disease, fulminant hepatic failure, hepatocellular carcinoma and MELD score of >15 or a Child-Pugh score of >10277.

# Historical Perspective
Autoimmune hepatitis was first to describe under the name of lupoid hepatitis in young females in early 1950. In 1950, Waldenstrom described a form of chronic hepatitis in young women. The term autoimmune hepatitis  was first used by the international panel. Gene mutations implicated in the pathogenesis of autoimmune hepatitis is C4 gene.

# Classification
According to European Association for the Study of the Liver, There are three types of autoimmune hepatitis based on the types of antibodies present- AIH type 1, AIH type 2, AIH type 3. Overlap syndrome is a type of syndrome found in a patient who presents with the features of AIH, PBC-AIH or PSC-AIH.

# Pathophysiology
Autoimmune hepatitis is a chronic disease characterized by inflammation of the liver which results from the combination of genetic predisposition and environmental triggers. The genetic predisposition is related to the defect in HLA haplotypes B8, B14, DR3,DR4, and Dw3, complement system, and T-cell level. The environmental factors involved are viruses like Rubella, Epstein-Barr, Hepatitis A, B, and C have molecular mimicry of viral sequences to host proteins and drugs like oxyphenisatin, methyldopa, nitrofurantoin, diclofenac, interferon, minocycline, and atorvastatin causes autoimmune hepatitis.

# Causes
Autoimmune hepatitis may be caused by the Drugs like minocycline, nitrofurantoin, hydralazine, methyldopa, statins, fenofibrate, interferon, infliximab, etanercept, viral infections e.g measles virus, EB virus, CMV and hepatitis A, B, C, D, E and if there is the history of other autoimmune diseases e.g graves disease, inflammatory bowel disease, rheumatoid arthritis, scleroderma, sjogren syndrome, systemic lupus erythematosus, thyroiditis, type 1 diabetes, ulcerative colitis.

# Differentiating Autoimmune Hepatitis from other Diseases
Autoimmune hepatitis must be differentiated from other diseases that cause jaundice, nausea and vomiting, abdominal pain, arthragia,  and hepatomegaly such as hepatitis A, B, C, E, drug-induced hepatitis, CMV hepatitis, EBV hepatitis, alcoholic hepatitis, primary biliary cirrhosis and primary sclerosing cholangitis.

# Epidemiology and Demographics
The incidence and prevalence of autoimmune hepatitis are generally higher among individuals of the whites of northern European ancestry with a high frequency of HLA-DR3 and HLA-DR4 markers.The incidence of autoimmune hepatitis approximately 1 to 2 per 100,000 individuals worldwide. Autoimmune hepatitis has bimodal distribution usually presents around puberty and between 4th and 6th decade, although a significant proportion is present in older people usually above 65 years of age. Young women are more commonly affected by autoimmune hepatitis than men.

# Risk Factors
Common risk factors in the development of autoimmune hepatitis include female gender, genetic predisposition associated with HLA-DR3 and HLA-DR4, and history of other autoimmune hepatitis eg. thyroiditis, type 1 diabetes, ulcerative colitis, celiac disease, and rheumatoid arthritis.

# Screening
According to the American Association for the Study of Liver Diseases, screening for autoimmune hepatitis is not recommended.

# Natural History, Complications and Prognosis
Autoimmune hepatitis has a bimodal age distribution, with the first peak of incidence at age 10-20 years and a second at age 45-70 years. Patients presents initially with no symptom but can progress to acute liver failure If not treated, patients can develop complications like Cirrhosis, Portal hypertension, ,Esophageal varices, metabolic bone disease, hyperlipidaemia, hypovitaminosis, Cholestasis. Prognosis is generally excellent, and the 10-year survival rate of patients with autoimmune hepatitis treated with immunosuppressive therapy is approximately 80%. The presence of young age at presentation, AIH-2, coagulopathy, severe histologic activity is associated with a poor prognosis among patients with autoimmune hepatitis.

# Diagnosis

## History and Symptoms
Patient with autoimmune hepatitis presents asymptomatic or with symptoms of acute liver failure. A positive history of viral infections like hepatitis A, C, and drug intake like minocycline, interferon , nitrofurantoin, infliximab, ezetimibe, interferon , ornidazole, diclofenac, indomethacin, terbinafine, methyldopa, ranitidine, atorvastatin, fluvastatin, fibrates, adalimumab is suggestive of autoimmune hepatitis. The common symptoms of autoimmune hepatitis include jaundice, fatigue, and  abdominal discomfort. Less common symptoms of autoimmune hepatitis include acne, edema, hirsutism, amenorrhea.

## Physical Examination
Patients with autoimmune hepatitis usually appear normal. Physical examination of patients with autoimmune hepatitis are jaundice, hepatomegaly, splenomegaly, hepatic encephalopathy and spider angiomata.

## Laboratory Findings

## Electrocardiogram
There are no ECG findings associated with autoimmune hepatitis.

## X Ray
There are no x-ray findings associated with autoimmune hepatitis.

## CT
There are no CT scan findings helps in diagnosing autoimmune hepatitis. However, a CT scan may be helpful in the diagnosis of complications of autoimmune hepatitis which include fibrosis, hepatomegaly, splenomegaly.

## MRI
There are MRI findings helps in diagnosing autoimmune hepatitis. However, an MRI is also helpful in the diagnosis of complications of autoimmune hepatitis which include fibrosis, hepatomegaly, splenomegaly.

## Ultrasound
There are ultrasound findings helps in diagnosing autoimmune hepatitis. However, an ultrasound is also helpful in the diagnosis of complications of autoimmune hepatitis Various findings are fibrosis, heterogeneous hepatic echotexture, hepatomegaly, splenomegaly and irregular nodular liver.

## Other Imaging Findings
Cholangiography is other imaging study to differentiate primary sclerosing cholangitis from autoimmune hepatitis.

## Other Diagnostic Studies
There are no other diagnostic studies associated with autoimmune hepatitis.

# Treatment

## Medical Therapy
Mainstay treatment of autoimmune hepatitis is pharmacotherapy. Corticosteroids alone or in combination with immunosuppressants are commonly used. Immunosuppressive treatment should be based on serum aspartate aminotransferase (AST), serum alanine aminotransferase (ALT), serum gamma-globulin levels, and histological features. Regimens are different for adults and children. According to the course of immunosupressants, further management is planned.

## Surgery
Liver transplantation is indicated when medical therapy fails, decompensated chronic liver disease, fulminant hepatic failure, hepatocellular carcinoma and MELD score of >15 or a Child-Pugh score of >10277. If AIH recurs after liver transplanation, Reintroduction of corticosteroids and azathioprine is usually given.

## Primary Prevention
There are no established measures for the primary prevention of autoimmune hepatitis.

## Secondary Prevention
There are no established measures for the secondary prevention of autoimmune hepatitis. There are measures to prevent complications like cirrhosis by eating high protein and low salt diet.