Abstract: Objective The aim of this study was to analyze the auxiliary diagnostic value of serum adenosine deaminase (ADA) and serum amyloid A (SAA) protein in patients with autoimmune hepatitis (AIH). Methods 60 patients with AIH, 98 patients with hepatitis B or C or alcoholic hepatitis (non-AIH group), and 100 healthy persons with normal physical examination Results were recruited between January 2017 and December 2018, and serum SAA and ADA, as well as serum antinuclear antibody (ANA), anti-liver-kidney microsomal antibody (LKM-1), anti-hepatocyte cytoplasmic antibody type I ( LC-1) and anti-soluble liver antigen/hepatic pancreatic antigen (SLA/LP) were detected. Results In AIH patients, serum SAA level was (58.7±6.2)mg/L, significantly higher than 【(12.3±2.5)mg/L, P<0.05】 in non-AIH patients or 【(6.3±1.2)mg/L, P<0.05】 in healthy persons, and serum ADA level was (88.4±10.1)U/L, significantly higher than 【(17.7±3.0)U/L, P<0.05】 in non-AIH patients or 【(10.3±2.1)mg/L, P<0.05】 in healthy persons; the prevalence of serum ANA, anti-LKM-1 and anti-SLA/LP in patients with AIH were 68.3%, 16.7% and 11.7%, while only 42.9%(P<0.05) of patients with non-AIH had serum ANA positive; in our series, the diagnostic sensitivity (Se), specificity (Sp) and accuracy (Ac) ANA were 68.3%, 57.1% and 60.0%, while when serum SAA level greater than 52.1 mg/L of serum or serum ADA level greater than 77.9 U/L was set as the cut-off-value, their auxiliary diagnostic Se, Sp and Ac were 76.7%, 89.8% and 70.4% on condition of exclusion of common etiologic reasons, such as viral hepatitis, fatty liver and drug-induced liver injuries in individuals with serum ALT elevation and serum autoimmune antibody negative. Conclusion As for individuals with serum ALT elevation and serum autoimmune antibody negative, the autoimmune hepatitis should be suspected as serum ADA or/and SAA level increases as common liver injury causes are excluded.

Key words: Autoimmune hepatitis, Serum amyloid A, Adenosine deaminase, Antinuclear antibody, Diagnosis