A 28 year old female presents with 1 week history of jaundice, fever and malaise. She was diagnosed with hypothyroidism for which she is receiving levothyroxine. Her blood tests show:
Serum bilirubin 40 μmol/L Alanine transferase (ALT) 120 iu/L Aspartate transaminase (AST) 90 iu/L Alkaline phosphatase (ALP) 200 iu/L Prothrombin time (PT) 25 sec
What is the SINGLE most likely diagnosis?
A. Acute on chronic liver failure
B. Hyperacute liver failure
C. Autoimmune hepatitis
D. Acute liver failure
E. Drug induced hepatitis
In autoimmune hepatitis, serum aminotransferases: aspartate aminotransferase (AST) and alanine aminotransferase (ALT) are usually elevated at initial presentation. Serum alkaline phosphatase is normal or only mildly raised. A more than two-fold elevation suggests an alternative or additional diagnosis. Hypoalbuminaemia and prolongation of prothrombin time are markers of severe hepatic synthetic dysfunction.
These lab test do not rule out other liver diseases but given the combination of the presence of another autoimmune disease like hypothyroidism, the most likely diagnosis here is autoimmune hepatitis.
Autoimmune hepatitis Autoimmune hepatitis (AIH) is a chronic disease of unknown cause, characterised by continuing hepatocellular inflammation and necrosis, which tends to progress to cirrhosis.
• Predominantly affects young or middle-aged women • Up to 40% present with acute hepatitis and signs of autoimmune disease, eg fever, malaise, urticarial rash, polyarthritis, pleurisy, pulmonary infiltration, or glomerulonephritis. The remainder present with gradual jaundice or are asymptomatic and diagnosed incidentally with signs of chronic liver disease. Amenorrhoea is common and disease tends to attenuate during pregnancy.
Investigations: The diagnosis rests on a combination of compatible biochemical, immunological and histological features together with exclusion of other liver diseases.
Associated diseases Concurrent autoimmune disorders occur in approximately 40% of patients, particularly autoimmune thyroid disorder