S5443 Acetaminophen Toxicity Delaying Recognition of Autoimmune Hepatitis in a Patient With Lupus

Introduction: Severe autoimmune hepatitis (AIH) and acetaminophen (APAP) toxicity can present with elevated liver enzymes, elevated international normalized ratio (INR) and jaundice. Both can lead to acute liver failure (ALF). We present a complex case of AIH confused for APAP toxicity in the setting of systemic lupus erythematosus (SLE). Case Description/Methods: A 38-year-old man with a history of SLE with lupus nephritis, antiphospholipid syndrome on warfarin, hypertension, hyperlipidemia presented with a complaint of 10 days of generalized joint pain and left flank pain. He had a history of lupus flares with joint pain and presumed that his symptoms were related to a lupus flare. He used up to 5,200 mg of APAP for his pain. He had not been on any medications for lupus as he was lost to follow up with rheumatology. On presentation, he had an INR of 6.6, sodium 132 mmol/L, aspartate aminotransferase 475 units/L, ALT 367 units/L, alkaline phosphatase 447 units/L, bilirubin 1.4 mg/dL and APAP level of 8 mg/mL. Given his history, APAP toxicity was suspected, and n-acetyl cysteine (NAC) was started with minimal improvement. His total bilirubin continued to increase, which led to a concern for ALF. Thus, transfer to a liver transplant center was planned. He never developed hepatic encephalopathy. Given the continued elevation in his liver function tests, AIH was considered. He was found to have an anti-smooth muscle antibody titer ratio of 1:110 with elevated IgG levels 3,072. He then underwent a liver biopsy which showed prominent inflammatory activity, Kupffer cell aggregates, marked lobular and portal hepatitis, which confirmed AIH. He was then started on prednisone 60 mg with clinical improvement. Once there was resolution in his cholestatic liver injury, he was started on azathioprine with a steroid taper. Discussion: There are dozens of documented cases of concurrent AIH and SLE. Thus, autoimmune hepatitis should be part of the differential of SLE patients with liver pathology. Here, APAP use in an SLE patient complicated the presentation and led to delayed recognition of AIH. Per the American Association for the Study of Liver Diseases, AIH is diagnosed with the presence of disease-congruent histological abnormalities (interface hepatitis), laboratory abnormalities (elevated liver enzymes and serum IgG concentration), and autoantibodies (antinuclear antibodies, smooth muscle antibodies, liver kidney microsome type 1 antibodies) and exclusion of resembling diseases. A broad differential without premature closure is important in evaluating and managing hepatic failure.