UNASSIGNED: Acute exacerbation of Autoimmune Hepatitis (AIH) poses a significant challenge for diagnosis as it can mimic acute viral hepatitis especially in absence of autoantibodies and hypergammaglobulinemia.
UNASSIGNED: To determine the clinical, laboratory, histopathological characteristics and response to treatment in AIH patients with acute exacerbation.
UNASSIGNED: A retrospective analysis of 16 patients with acute exacerbation of AIH diagnosed over a period of eight years (2008-2016).
UNASSIGNED: Out of the 111 patients diagnosed with AIH, acute exacerbation of AIH was diagnosed in 16 (14.4%) patients. All patients were females with median age of 35 years. Nine patients (56%) had Type 1 AIH and seven (44%) patients were diagnosed with seronegative AIH. All 16 (100%) patients had acute viral hepatitis like illness at presentation. The median bilirubin was 4.2 mg/dl (range, 2.2-20), aspartate transaminase was 568 IU/L (range, 390-908), alanine transaminase was 430 IU/L (range, 257-1026) and serum alkaline phosphatase was 395 IU/L (range, 112-890) during symptomatic period. The histopathological examination showed underlying chronic hepatitis in 10 (71.4%) patients, only fibrosis in 2 (14.2) patients and cirrhosis with activity in 2 (14.2%). All 16 (100%) patients were treated with a combination of steroids and azathioprine. Thirteen (81%) patients achieved complete biochemical remission and three (19%) patients achieved partial remission out of which one (6%) patient succumbed to illness because of the complications of cirrhosis.
UNASSIGNED: A suspicion of acute exacerbation of AIH should be considered in patients with unexplained acute hepatitis mimicking acute viral hepatitis in the absence of positive viral markers. Through evaluation with immunoserological markers and liver biopsy can clinch the diagnosis of acute exacerbation of AIH in such cases.

Autoimmune hepatitis (AIH) is a chronic immune mediated liver disease characterized by elevated transaminases, hyper gammaglobulinemia, presence of autoantibodies and interface hepatitis in the absence of a known etiology of liver disease. Thiopurines (azathioprine [AZA]/6-mercaptopurine [6MP]) and steroids remain the first line of treatment of AIH in both children and adults. However, a small proportion of AIH patients are either non-responders or develop side effects with AZA. The metabolism of AZA is complex and mediated by multiple enzymes. After absorption and getting converted to 6MP, it is converted to 6-thiouric acid, 6-methyl mercaptopurine (6MMP) and 6-thioguanine (6TG) by different enzymes. Elevated 6MMP levels are associated with hepatotoxicity and also poor efficacy due to simultaneous lower levels of 6TG, which is the active drug metabolite related to both efficacy and myelosuppression. Allopurinol, a xanthine oxidase inhibitor shifts the metabolism of AZA away from 6MMP toward 6TG. This combination of allopurinol with reduced dose of AZA is an alternative to more expensive and toxic second line therapy to induce remission in patients with AIH. This article discusses the mechanism of action of allopurinol in inducing response to AZA, reviews the published literature on this combination therapy and gives guidelines on the use of allopurinol in patients with AIH.