In a previously healthy 20‑year‑old woman with a 7‑day history of worsening jaundice, nausea, vomiting, right upper‑quadrant pain, markedly elevated aspartate aminotransferase (AST) and alanine aminotransferase (ALT), modestly increased alkaline phosphatase, and total bilirubin of 26 µmol/L, which laboratory test—bilirubin, albumin, prothrombin time, or ALT—provides the greatest prognostic value?

Prothrombin Time Has the Greatest Prognostic Value

In this young woman with acute hepatocellular injury (markedly elevated transaminases with jaundice), prothrombin time provides the most critical prognostic information because it directly reflects hepatic synthetic function and distinguishes patients who will survive from those requiring urgent liver transplantation. 1, 2

Why Prothrombin Time is Superior for Prognosis

Direct Assessment of Liver Synthetic Capacity

• Prothrombin time measures the liver's ability to synthesize clotting factors, which is the most accurate gauge of hepatic protein synthetic ability and overall liver function 2
• Unlike transaminases (which only reflect ongoing hepatocellular injury), PT/INR indicates whether the liver retains sufficient functional capacity to sustain life 1, 2
• Coagulopathy unresponsive to parenteral vitamin K administration is a hallmark of fulminant hepatic failure and predicts mortality 1

Established Prognostic Utility in Acute Liver Injury

• A prognostic index for acute fulminant Wilson disease (which this patient's presentation could represent) is based on total serum bilirubin, AST, and prolongation of prothrombin time—notably including PT but not albumin or isolated ALT 1
• Prolonged PT combined with elevated bilirubin constitutes a medical emergency requiring immediate specialist evaluation, as this pattern indicates impending acute liver failure 1

Why the Other Options Are Less Prognostic

Bilirubin (Option A)

• While bilirubin at 26 µmol/L indicates jaundice, this level is only mildly elevated and does not by itself predict outcome 1
• Bilirubin is "probably the best test of overall liver function" for chronic disease monitoring, but in acute presentations, it must be combined with PT to assess prognosis 1, 2

Albumin (Option B)

• Albumin has a half-life of approximately 20 days, making it a poor marker for acute hepatic injury 2
• In this 7-day illness, albumin levels will still reflect pre-illness synthetic function rather than current hepatic capacity 2
• The prognostic index for acute liver failure specifically uses PT rather than albumin for this reason 1

ALT (Option D)

• ALT reflects the magnitude of hepatocellular injury but not residual liver function 2, 3
• The "relatively modest elevations of serum aminotransferase activity" (typically <2000 IU/L) seen in fulminant Wilson disease often lead clinicians to underestimate disease severity 1
• This patient's ALT of 1650 IU/L, while markedly elevated, provides a "day-by-day account of hepatocellular injury and death" but does not predict survival 2

Critical Clinical Context

Pattern Recognition for Fulminant Hepatic Failure

This 20-year-old woman's presentation warrants immediate assessment for:

• Wilson disease: Young age, modest transaminase elevations relative to clinical severity, and the characteristic pattern of AST potentially approaching or exceeding ALT 1
• Autoimmune hepatitis: Young women are at higher risk, and this can present with acute hepatocellular injury 1
• Drug-induced liver injury or viral hepatitis: Both can cause this pattern but typically show higher transaminase elevations 1

The Prognostic Algorithm

If PT is prolonged (elevated INR):

• Combined with bilirubin >2× ULN → medical emergency requiring immediate hepatology consultation 1
• Unresponsive to vitamin K → indicates true synthetic dysfunction rather than vitamin K deficiency 1
• Requires urgent evaluation for liver transplantation 1

If PT remains normal:

• Despite elevated transaminases and bilirubin, this suggests preserved synthetic function
• Patient more likely to recover with supportive care or medical management 1, 2

Common Pitfall to Avoid

Do not be falsely reassured by "only" modest transaminase elevations (AST 700, ALT 1650) in a jaundiced patient with right upper quadrant pain 1. In fulminant Wilson disease and other causes of acute liver failure, the relatively low transaminases compared to the severity of illness is characteristic and often leads to delayed diagnosis 1. The PT will reveal the true severity.