Low-grade elevation of fibrinogen-degradation products is an important parameter to identify acute presentation of autoimmune hepatitis

Objective: Diagnosing early-stage acute autoimmune hepatitis (AIH) without pathological findings is difficult. Recent reports indicated that macrophages are not activated during disease development, unlike in other acute liver injuries. We suggest that hepatitis without macrophage activation should lack sinusoidal fibrin deposition, which might help diagnose the acute presentation of AIH. Material and methods: To test this hypothesis, 295 consecutive patients with acute liver injury enrolled into this study. Their clinical data on admission were analyzed to verify the differences between acute presentation of AIH and other liver injuries. Results: The distribution of plasma fibrinogen degradation products (FDP) showed two clusters: patients without elevated FDP and those with measurable FDP levels of various degrees. Most AIH patients are included in the former. Multivariate logistic analysis of patients’ laboratory data was performed for useful parameters to identify the acute presentation of AIH. FDP, alanine transaminase, zinc sulfate turbidity test and HBsAg levels were significant. Based on the odds ratio obtained from the analysis, we assigned each result individual points and constructed a convenient scoring system, which showed high sensitivity and specificity to identify AIH. Additionally, the area under the receiver operating characteristic curve was 0.928. Conclusions: Our results indicated that the process of macrophage activation and subsequent sinusoidal fibrin deposition was not involved in the development of the acute presentation of AIH. Our new scoring system including FDP levels could contribute to rapid diagnosis of the acute presentation of AIH without liver biopsy.