Liver Test Interpretation and Workup

• Audio chapter
  Single-voice audio, listen on the commute.
• ABIM-format MCQs
  5-option vignettes with full wrong-answer teaching.
• Study guide
  Tables, decision trees, primary sources.
• AI tutor
  Chapter-grounded, answers the question you're stuck on.

What this chapter covers

• Section 17.1: Pattern recognition and the R ratio

  Abnormal liver tests are not a diagnosis.

• Section 17.2: Hepatocellular workup

  A patient with hepatocellular injury (R over 5) gets a layered workup that is sequenced by pretest probability and reversibility.

• Section 17.3: Cholestatic workup

  Cholestatic injury (R under 2) is worked up with imaging first, because the next step depends on whether the biliary tree is dilated.

• Section 17.4: Isolated hyperbilirubinemia

  A patient with elevated bilirubin and otherwise normal aminotransferases, alkaline phosphatase, albumin, and INR has isolated hyperbilirubinemia, and the workup splits at the very first lab: is the elevation predominantly indirect (unconjugated) or direct (conjugated)?

• Section 17.5: Isolated alkaline phosphatase elevation

  Alkaline phosphatase comes from multiple tissues and an isolated elevation does not necessarily mean liver disease.

• Section 17.6: Imaging modalities and noninvasive fibrosis

  Noninvasive assessment of liver disease has restructured hepatology over the last 15 years, and each test answers a specific question at a specific cutoff.

• Section 17.7: Liver biopsy indications and techniques

  Liver biopsy has narrowed in indication as noninvasive tools have improved, but it remains indicated when staging is uncertain, when overlapping diagnoses cannot be separated by serology, when the etiology is unclear after a complete biochemical and noninvasive workup, and when transjugular access provides additional hemodynamic information that imaging alone cannot supply.

Podcast episodes

1. 01

   Liver Test Interpretation: Patterns and Workup

   An abnormal liver test is a screening signal, and the workup is organized by which enzyme dominates and by how many multiples of normal it sits at. The episode first redefines a normal ALT, then sets the pattern with the R ratio, reads the size of the elevation, and uses the AST-to-ALT ratio. Hepatocellular injury is worked up in one round across the viral, autoimmune, metabolic and inherited, ischemic, and drug layers, with a full supplement history, while shock liver and herpes simplex hepatitis are recognized by pattern. Cholestasis starts with ultrasound, then MRCP for dilated ducts, AMA for a normal tree, MRCP for primary sclerosing cholangitis, and IgG4 for stricture mimics.

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2. 02

   Liver Test Interpretation: Workup and Staging

   The organizing idea is to match the test to the question. An isolated bilirubin is split into indirect and direct, hemolysis is excluded, and the benign inherited syndromes are told apart. An isolated alkaline phosphatase is traced to liver or bone with the GGT, and a hepatic source is checked for infiltrative disease. Fibrosis is then staged without biopsy, starting with FIB-4, then FibroScan, then MR elastography when results are unreliable or disagree, with stiffness cutoffs that differ by disease. Biopsy comes last, only when it changes management, and the approach depends on ascites, clotting, and whether portal pressure is wanted. The hepatic venous pressure gradient then measures what no image can.

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Key topics

• ·True upper limit of normal ALT
• ·R ratio and injury pattern
• ·Size of the aminotransferase elevation
• ·AST-to-ALT ratio
• ·Five-layer hepatocellular workup
• ·Supplements, Hy's law, and drug injury
• ·Ischemic hepatitis and herpes simplex hepatitis
• ·Ultrasound first in cholestasis
• ·Primary sclerosing cholangitis and primary biliary cholangitis
• ·IgG4-related sclerosing cholangitis
• ·Direct versus indirect bilirubin
• ·Hemolysis screen
• ·Gilbert and Crigler-Najjar syndromes
• ·Dubin-Johnson and Rotor syndromes
• ·GGT and the source of alkaline phosphatase
• ·Infiltrative causes of high alkaline phosphatase
• ·FIB-4 and blood fibrosis scores
• ·FibroScan and MR elastography
• ·Indications and routes for liver biopsy
• ·Hepatic venous pressure gradient