Acute Liver Failure During Thyroid Storm With Autoimmune Hepatitis Overlap: A Rare Immunoendocrine-Hepatic Intersection.

A previously healthy 24-year-old woman presented with jaundice, diarrhea, tachycardia, fever, and altered mental status. Laboratory evaluation revealed severe hyperbilirubinemia, mixed hepatocellular-cholestatic injury, international normalized ratio 4.99, hypofibrinogenemia, and encephalopathy, fulfilling criteria for acute liver failure (ALF). Thyroid studies demonstrated suppressed thyroid-stimulating hormone, elevated free thyroxine and triiodothyronine, and strongly positive anti-thyroid peroxidase and anti-thyroid‑stimulating hormone receptor antibodies, confirming thyroid storm. Profound hypergammaglobulinemia (immunoglobulin G 9,079 mg/dL), anti-smooth muscle antibody positivity (1:40), and antinuclear antibody positivity (1:80) suggested autoimmune hepatitis (AIH) overlap. Immunoglobulin M levels were not available. AIH frequently coexists with other autoimmune disorders, occurring in up to 20%-30% of cases, and may exacerbate liver injury during endocrine crises. Despite corticosteroids, iodine therapy, and supportive care, the patient deteriorated and died. This case highlights the rare intersection between thyroid storm, ALF, and AIH overlap, emphasizing the importance of early recognition of autoimmune markers in endocrine emergencies.