From the Guidelines
Autoimmune Hepatitis (AIH) is diagnosed by integrating laboratory findings, the presence of autoantibodies, and compatible histologic findings, with the simplified diagnostic scoring system being a useful tool in everyday clinical practice.
Diagnostic Criteria
The diagnostic criteria for AIH include:
- Presence and titer of autoantibodies such as ANA, SMA, anti-LKM1, anti-LC1, anti-SLA, or ANCA 1
- Serum IgG concentration, with increased levels found in approximately 85% of patients with AIH 1
- Presence of typical or compatible histology, with features such as interface hepatitis, lymphocytic/lymphoplasmacytic infiltrates, and hepatic rosette formation 1
- Absence of viral hepatitis markers, although co-existence of AIH and viral hepatitis may occur in some cases 1
Simplified Diagnostic Scoring System
The simplified diagnostic scoring system, proposed by the IAIHG in 2008, is based on four parameters:
- Autoantibodies: +1 to +2 points depending on the titer and type of autoantibody 1
- IgG or γ-globulins level: +1 to +2 points depending on the level of elevation 1
- Liver histology: +1 to +2 points depending on the presence of typical or compatible features 1
- Absence of viral hepatitis: +2 points 1 A definite diagnosis of AIH is made with a score of 7 or higher, while a probable diagnosis is made with a score of 6 1.
Clinical Considerations
The diagnosis of AIH should be made in conjunction with clinical judgment, taking into account the patient's presentation, medical history, and other diagnostic findings 1. In cases where the diagnosis is uncertain, a liver biopsy may be necessary to confirm the presence of AIH 1. Additionally, other autoimmune diseases may co-exist with AIH, and their presence should be considered in the diagnostic workup 1.
From the Research
Diagnostic Criteria for Autoimmune Hepatitis (AIH)
The diagnostic criteria for AIH are based on a combination of clinical, laboratory, and histological findings. The International Autoimmune Hepatitis Group (IAIHG) has established diagnostic criteria, which have been revised and simplified over time 2, 3, 4. The simplified criteria include:
- Autoantibodies
- Immunoglobulin G levels
- Histology
- Exclusion of viral hepatitis
Scoring Systems
The IAIHG has developed scoring systems to facilitate the diagnosis of AIH. The scoring systems assign points for various parameters, and a total score is calculated to determine the likelihood of AIH. The simplified scoring system has been shown to have high specificity and sensitivity for diagnosing AIH 2, 4. The scoring systems are as follows:
- A score of 6 or higher indicates probable AIH
- A score of 7 or higher indicates definite AIH
Limitations and Challenges
The diagnosis of AIH can be challenging, especially in patients with atypical presentations or concomitant liver diseases 5, 3, 4. The scoring systems may not perform well in these patients, and liver biopsy may be necessary to establish a definitive diagnosis 6. Additionally, the simplified criteria may have lower sensitivity for scores of 7 or higher, which may be due to the loss of discriminating information such as response to corticosteroids 4.