Elevated serum immunoglobulin G levels in patients with chronic liver disease in comparison to patients with autoimmune hepatitis

BACKGROUND: Hypergammaglobulinemia is frequently observed in patients with chronic liver disease (CLD) of different causes. On the other hand, elevated levels of serum immunoglobulin G (IgG) are the best diagnostic marker for autoimmune hepatitis (AIH). Thus, the ability to distinguish AIH patients from patients with other liver disease, especially patients with advanced liver cirrhosis, is important since most AIH patients will a have favorable treatment response if diagnosed properly. OBJECTIVE: We conducted this study to evaluate the significance of elevated IgG levels in patients with non-autoimmune CLD and to compare these IgG levels with those in patients with AIH upon diagnosis. SETTING AND STUDY POPULATION: The serum IgG levels in 27 patients with AIH determined at the time of diagnosis were compared to the serum IgG levels in 27 patients with other CLDs of variable severity at the King Abdul Aziz University Hospital in Jeddah, Saudi Arabia. Severity of the disease was evaluated in all patients. RESULTS: We found that the patients in the CLD group with decompensated cirrhosis had significantly higher serum IgG levels compared to the compensated CLD patients (p <0.02). In addition, the AIH patients had significantly higher serum IgG levels than the non-autoimmune hepatitis CLD patients and the decompensated cirrhosis patients in the CLD group (p <0.001 and p <0.044, respectively). Most patients with elevated serum IgG of the AIH group (67%) and the CLD group (75%) had significant hypergammaglobulinemia, not just isolated elevated IgG levels. CONCLUSION: Elevated serum IgG levels with hypergammaglobulinemia are commonly found in patients with advanced CLD. The differentiation of such cases from AIH is important in order to avoid misdiagnosis and confusion with AIH.