The Diagnostic Maze: Challenges in Autoimmune Hepatitis Lab Interpretation.

Autoimmune hepatitis (AIH) is a chronic inflammatory liver disease characterized by the presence of circulating autoantibodies. The spectrum of disease manifestations extends from asymptomatic cases to mild symptoms and, in rare instances, acute liver failure. AIH is a diagnosis of exclusion, supported by the detection of autoantibodies such as anti-smooth muscle antibody (ASMA). This case describes a 43-year-old female with myasthenia gravis, receiving monthly intravenous immunoglobulin (IVIG) infusions, who presented with persistently elevated liver enzymes and mildly elevated ASMA titers across multiple clinical encounters. A liver biopsy revealed severe acute hepatitis. While drug-induced liver injury (DILI) secondary to IVIG was initially considered the leading diagnosis, the persistence of elevated liver enzymes over two months despite discontinuation of IVIG made the diagnosis of AIH more likely and brought attention to the diagnostic challenges associated with AIH. Although ASMA is a hallmark serologic marker for AIH, it only has a moderate sensitivity of 59 %. Furthermore, IVIG administration may interfere with autoimmune testing, potentially leading to false-negative results. This case illustrates the complexity of interpreting autoimmune serologies and emphasizes the need for comprehensive diagnostic approach. It also highlights the importance of recognizing cognitive biases, such as premature diagnostic closure, that can hinder accurate diagnosis.