Abstract: Objective To investigate the clinical features in patients with cryptogenic hepatitis and establish a standardized road-map for diagnosis of them. Methods Patients with elevated serum alanine aminotransferase （ALT） levels from 2010 to 2013 were included in this study. Patients passed through screening,detailed examination,and follow-up stages as necessary. History-taking,physical examination,radiography,blood tests including highly sensitive detection of virus nucleic acid and gene locus testing,liver histopathology and immunohistochemistry and diagnostic scoring system were applied to find out the etiology. Results A total of 143 patients（14.3%） with cryptogenic hepatitis were left from 1000 individuals with elevated serum ALT levels;After detailed examination and/or follow-up for months,21 patients got diagnosis including three with hepatitis B,four with viral hepatitis,thirteen with autoimmune liver diseases,and one with drug-induced liver injury,while the causes in other 122 cases（12.2%） were still unknown;Serum ALT and TBIL levels in the 122 patients with cryptogenic hepatitis were （640.01±596.67） IU/L and （118.41±142.64） μmol/L;Out of the 122 patients,53.3%（65/122） had fatigue,71.3%（87/122） had gastrointestinal symptoms,and 50.0%（61/122）had jaundice;The liver histopathologic exam showed that 87.5% （70/80） got mild to moderate histological activity index and 72.1%（88/122）patients got good prognosis. Conclusions At present,about 10% of patients with elevated serum ALT levels are cryptogenic,although the detailed screening processes and very highly sensitive tests can be applied for the clinical practice.

Key words: Elevated serum alanine aminotransferase levels, Cryptogenic, Clinical features, Liver pathology