A 38-year-old woman with a 10-year history of primary biliary cholangitis (PBC) presents with jaundice, pruritus, and pale stools. Her serum bilirubin is 4.2 mg/dL (predominantly direct), ALP 320 U/L, and ALT 45 U/L. A 42-year-old man with acute viral hepatitis A presents with jaundice, dark urine, and malaise. His serum bilirubin is 6.8 mg/dL (predominantly direct), ALP 95 U/L, and ALT 2200 U/L. Which single feature best distinguishes cholestasis (PBC) from hepatocellular injury (acute hepatitis)?