OBJECTIVES: Immunoglobulin G (IgG) elevation is a key laboratory finding of autoimmune hepatitis (AIH). However, the IgG elevation also occurs in patients with cirrhosis due to diverse etiologies. Therefore, we compared serum levels of globulin (GLB) and immunoglobulins among cirrhotic patients and optimized the IgG level to improve its diagnostic accuracy for AIH in the context of cirrhosis. METHODS: In this cross-sectional study, we included age- and gender-matched patients with cirrhosis due to AIH and non-AIH etiologies. Demographic and key laboratory profiles were compared, focusing on the levels of GLB and immunoglobulins. Receiver operating characteristic curves were constructed. Bilateral P < 0.05 and area under receiver operating characteristic curves greater than 0.5 were considered statistically significant. RESULTS: A total of 60 AIH patients and 259 patients with cirrhosis of non-AIH etiologies were analyzed. The AIH group exhibited higher alanine aminotransferase and aspartate aminotransferase levels. Elevations of GLB (9.8-58.3%) and IgG (47.4-97.2%) levels were observed in all groups of cirrhosis, with the highest levels of IgG, immunoglobulin M, and immunoglobulin A occurring in the patients with cirrhosis due to AIH, primary biliary cholangitis, and alcoholic liver disease group, respectively. At a cutoff IgG level of 2000 mg/dl (1.25× upper limit of normal), the sensitivity and specificity for the diagnosis of AIH cirrhosis were 81.7% and 74.1%, respectively, with an area under receiver operating characteristic curves of 0.814 (P < 0.001). CONCLUSION: Hyperimmunoglobulinemia occurs in patients with cirrhosis due to different etiology. However, the different patterns of immunoglobulin subtype elevation may facilitate the differentiation of the underlying etiology of cirrhosis, with IgG level more than 2000 mg/dl (1.25× upper limit of normal) having a fair diagnostic performance for AIH-related cirrhosis.
Su et al. (Tue,) studied this question.