Thread by @DocPriyamMD

Med students, listen up! Today let me explain how to analyze a Liver Function Test (LFT) step by step.
​Stop looking at isolated HIGH or LOW flags on a lab report. You need to look at the patterns. Here is how you actually read an LFT panel like a CONSULTANT 👇 (1/10)

Hepatocellular Injury (AST & ALT)
Look at the ratio and the absolute numbers:

• Mild rise + ALT > AST: Think MAFLD. Extremely common incidental finding.

• Modest rise + AST:ALT > 2:1: Alcoholic hepatitis. (Alcohol depletes B6, which limits ALT synthesis). (2/10)

• Massive Elevation (>1000 U/L)
This is a medical emergency indicating widespread hepatocyte death.

Causes: Ischemic Hepatitis, Acetaminophen Toxicity or Acute Viral Hepatitis. You must track the kinetic spike and drop over 24-48 hours (3/10)

Bilirubin (Excretion Pathway)

• Unconjugated (Indirect) Dominant: Pre-hepatic. Think hemolysis or overproduction.

• Conjugated (Direct) Dominant: Post-hepatic. The liver processed it, but there is an obstruction (like a gallstone) preventing excretion (4/10)

Acute Viral Hepatitis Pattern

Transaminases shoot into the thousands with strict ALT > AST dominance. This is accompanied by a steady, parallel rise in both total and direct bilirubin. Jaundice worsens as the enzymes peak (5/10)

Tropical Fever Patterns (High Yield)

• Leptospirosis: Disproportionately massive Bilirubin (deep jaundice) with only mildly elevated AST/ALT (<200).

• Scrub Typhus: Significantly high AST/ALT (mid-hundreds) but Bilirubin and jaundice stay relatively mild (6/10)

Synthetic Function (Chronic Liver Disease)

• Albumin: Half-life is ~20 days. Drops in chronic failure (Cirrhosis).

• Flipped A:G Ratio (<1): Albumin drops while unfiltered gut antigens drive up Globulin. A classic chronic liver disease sign (7/10)

ALP & GGT

• ALP shoots up when bile ducts are blocked. But ALP also lives in bone.
How do you differentiate? Check GGT. GGT only rises for liver issues.

High ALP + High GGT = Biliary block.
High ALP + Normal GGT = Bone issue.
(8/10)

Clotting (PT/INR)

• While Albumin takes weeks to drop, clotting factors drop in hours. A rising INR in acute hepatitis means the liver is actively failing right now. It is the ultimate red flag for acute liver failure.
(9/10)

Hi, I am Dr. Priyam, an MD Internal Medicine resident. I make medical content to bridge the gap between laymen and students. I teach clinical concepts and share my real-world hospital experiences.

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