Não há um exame que confirme exatamente o diagnóstico. A partir de suspeita pelas queixas do paciente e pelo exame clínico, o médico solicita exames de sangue que visam excluir outras causas mais comuns de hepatite, como, por exemplo, as causadas por vírus.
Dentre os exames que induzem fortemente o diagnóstico estão os que detectam anticorpos sanguíneos anormais.
Ecografia e biópsia hepática (retirada com agulha de um pequeno fragmento do fígado) são usadas para elaboração do diagnóstico, podendo demonstrar desde inflamação leve e diferente da hepatite por vírus até cirrose.
Diagnostic Criteria for Autoimmune Hepatitis (AIH)
| Requisites | Diagnostic Criteria | |
| Definite | Probable | |
| No genetic liver disease | Normal alpha1 antitrypsin phenotype Normal serum ceruloplasmin, iron, and ferritin levels |
Partial alpha1 antitrypsin deficiency Nonspecific serum copper, ceruloplasmin, iron, and/or ferritin abnormalities |
| No active viral infection | No markers of current infection with hepatitis A, B, and C viruses | No markers of current infection with hepatitis A, B, and C viruses |
| No toxic or alcohol injury | Daily alcohol < 25 g/d and no recent use of hepatotoxic drugs | Daily alcohol < 50 g/d and no recent use of hepatotoxic drugs |
| Laboratory features | Predominant serum aminotransferase abnormality Globulin, gamma-globulin or immunoglobulin G level >/= 1.5 times normal |
Predominant serum aminotransferase abnormality Hypergammaglobulinemia of any degree |
| Autoantibodies | ANA, SMA, or anti-LKM1 >/= 1:80 in adults and >/=1:20 in children; no AMA | ANA, SMA, or anti-LKM1 >/= 1:40 in adults or other autoantibodies* |
| Histologic findings | Interface hepatitis No biliary lesions, granulomas, or prominent changes suggestive of another disease |
Interface hepatitis No biliary lesions, granulomas, or prominent changes suggestive of another disease |
Diagnostic Scoring System for Atypical Autoimmune Hepatitis in Adults
| Category | Factor | Score |
| Gender | Female | +2 |
| Alk Phos:AST (or ALT) ratio | >3 <1.5 |
-2 +2 |
| Gamma-globulin or IgG (times above upper limit of normal) | >2.0 1.5-2.0 1.0-1.5 <1.0 |
+3 +2 +1 0 |
| ANA, SMA, or anti-LKM1 titers | >1:80 1:80 1:40 <1:40 |
+3 +2 +1 0 |
| AMA | Positive | -4 |
| Viral markers of active infection | Positive Negative |
-3 +3 |
| Hepatotoxic drugs | Yes No |
-4 +1 |
| Alcohol | <25 g/d >60 g/d |
+2 -2 |
| Concurrent immune disease | Any nonhepatic disease of an immune nature | +2 |
| Other autoantibodies* | Anti-SLA/LP, actin, LC1, pANCA | +2 |
| Histologic features | Interface hepatitis Plasma cells Rosettes None of above Biliary changes Atypical features |
+3 +1 +1 -5 -3 -3 |
|
HLA |
DR3 or DR4 |
+1 |
|
Treatment response |
Remission alone |
+2 |
|
Pretreatment score |
|
>15 >17 |
