What Is Type 1 Autoimmune Hepatitis?
What Is Type 1 Autoimmune Hepatitis?
Autoimmune hepatitis is a rare autoimmune disease, which is subdivided into Type 1 and Type 2 autoimmune hepatitis. Type 1 autoimmune hepatitis is more common than type 2 and accounts for nearly 96% cases in United States, whereas type 2 accounts for only 4% cases. Type 1 autoimmune hepatitis is characterized by the presence of antinuclear antibodies (ANAs) and smooth muscle antibodies (SMAs). It is more predominant in females than males with a ratio of 4:1.
It is the inflammation of liver due to destruction of liver cells by body’s own immune system. It is mostly associated with other autoimmune diseases such as lupus, rheumatoid arthritis, inflammatory bowel disease, Grave’s disease, vitiligo, autoimmune thyroiditis, Sjogren’s syndrome and ulcerative colitis. Females around the age of 15-40 are more susceptible to it with a family history of other autoimmune diseases, but anyone can get it. Untreated autoimmune hepatitis leads to liver cirrhosis and eventually liver failure.
Causes of Type 1 Autoimmune Hepatitis
Generally, the cause of type 1 autoimmune hepatitis is still not very clear, but it is thought to have a genetic predisposition as it runs in families. It is also associated with other autoimmune diseases as mentioned above. It is thought to be triggered by environmental factors that cause loss of tolerance of T lymphocytes with subsequent attack on hepatic cells. The other possible environmental triggers are viruses (Epstein Barr virus and hepatitis A virus) and drugs such as nitrofurantoin, minocycline, halothane, atorvastatin, isoniazide, diclofenac and propylthiouracil.
Symptoms of Type 1 Autoimmune Hepatitis
The clinical presentation of type 1 autoimmune hepatitis is diverse, as patients may present with no symptoms to acute liver failure. The patients who are asymptomatic are diagnosed incidentally. The classical symptoms include arthralgia (joint pain), anorexia (loss of appetite), fatigue and maculopapular rash, but they are not always present.
Other constitutional symptoms include nausea, vomiting, abdominal pain, weight loss, dark yellow urine, diarrhea, light colored feces and amenorrhea in women. Some patients may develop cirrhosis and will present symptoms related to that including itching, bruising, prolonged bleeding, abdominal and extremity swelling, varicose veins, jaundice and confusion.
Diagnosis of Type 1 Autoimmune Hepatitis
There is no particular definitive test for the diagnosis of type 1 autoimmune hepatitis, but the diagnosis is made by cumulative results of clinical presentation and various lab tests. The diagnosis of type 1 autoimmune hepatitis should exclude other chronic hepatitis such as chronic alcohol induced hepatitis, drug induced hepatitis, primary biliary cirrhosis and primary sclerosing cholangitis. The diagnostic criteria include elevation of ALT and AST nearly 5-10 times the upper limit of normal, elevation of gamma globulins and IgG antibodies nearly 1.5 times the upper limit of normal, presence of antinuclear antibodies (ANAs) and smooth muscle antibodies (SMAs) and female sex. In addition, they should have negative markers for hepatitis A, B and C along with Wilson’s disease, absence of hepatotoxic drugs and alcohol consumption of <25 mg/day. A liver biopsy with interface hepatitis is vital to the diagnosis of type 1 autoimmune hepatitis.
Treatment of Type 1 Autoimmune Hepatitis
The treatment of type 1 autoimmune hepatitis is aimed to reduce inflammation of liver by immunosuppression and corticosteroid therapy is the foundation of the treatment. It is treated with either high dose prednisone monotherapy, a combination of prednisone and azathioprine or with a combination of budesonide and azathioprine.
The goal of treatment is to prevent liver failure and end stage liver disease, which is usually achieved in 80% cases of type 1 autoimmune hepatitis approximately after 1-2 years of initiation of treatment. Thus, corticosteroid therapy is extremely helpful in suppressing the disease progression and liver damage. Liver transplantation is the only option if there is acute liver failure, decompensated liver cirrhosis, end stage liver disease and hepatocellular carcinoma. However, if the disease is diagnosed early, it can be managed really well by medications with success. The patients who are responsive to treatment have good prognosis and survival rate.
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