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) splits cleanly along an imaging-first line, because the workup branches at 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 the boards expect candidates to know which test answers which question and at what cutoff.

• Section 17.7: Liver biopsy indications and techniques

  Liver biopsy has narrowed in indication as noninvasive tools have improved, but it remains the answer 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

   The R Ratio and the Two Workup Tracks

   Episode one of the Liver Test Interpretation chapter turns abnormal liver enzymes into a workup by computing the R ratio and committing to a track before ordering another test. The organizing idea: which enzyme dominates and by how many multiples of normal it sits at frames the entire differential, because hepatocellular and cholestatic patterns share almost nothing. The hepatocellular track runs five layers in order (viral, autoimmune, metabolic, ischemic, drug); the cholestatic track branches on a single ultrasound finding, dilated tree or not. Thresholds, magnitude anchors, and reflex panels throughout.

   Read the transcript →
2. 02

   Isolated Abnormalities, Imaging, and Biopsy

   Episode two of the Liver Test Interpretation chapter covers what to do when a single value is up with everything else normal, or when the labs aren't the bottleneck and imaging and fibrosis assessment are. Each case forces the same question in a different form: what's the next reflex test, and does it commit you to an invasive workup or excuse you from it? Isolated bilirubin splits on direct versus indirect, isolated alkaline phosphatase splits on GGT, and the fibrosis workup runs FIB-4 before elastography before biopsy. Thresholds, mimic vignettes, and the percutaneous-versus-transjugular decision throughout.

   Read the transcript →

Key topics

• ·The R ratio and sorting hepatocellular from cholestatic
• ·Hepatocellular injury and magnitude-based differential
• ·AST-to-ALT ratio and the redefined normal range
• ·Hepatocellular workup: viral, autoimmune, metabolic layers
• ·Ischemic (shock liver) and drug-induced injury with Hy's Law
• ·Cholestatic workup and the ultrasound branch point
• ·Intrahepatic cholestasis: PBC, PSC, and IgG4 disease
• ·The mixed pattern and the synthesis
• ·Isolated hyperbilirubinemia and the direct versus indirect split
• ·Separating hemolysis from Gilbert on the indirect side
• ·Direct hyperbilirubinemia: Dubin-Johnson and Rotor
• ·Isolated alkaline phosphatase and the GGT discriminator
• ·Imaging modalities: structure versus fibrosis
• ·Transient and MR elastography cutoffs by etiology
• ·Serum fibrosis biomarkers and the FIB-4 sequence
• ·Liver biopsy indications and technique
• ·Percutaneous versus transjugular and the pressure gradient