Liver “Function” Test
2013
MINI-LECTURE
Objectives
 Understand the significance of Liver Function Tests
 Identify the patterns that indicate specific disease
categories
 Identify the appropriate further work up of
abnormalities
Case
 49 year old Female presents with chest pain and
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negative troponins admitted for monitoring, LFT in
ED show AST: 57, ALT: 62, Alk Phos: wnl, T. Bili:
wnl. What is the next step in management?
A: RUQ Ultrasound
B: Hepatitis Panel
C: Screen for Alcohol Use
D: CT Scan Abdomen
Etiology
 Synthetic Function: Total protein, serum albumin,
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total bilirubin, prothrombin time
ALT: found primarily in Hepatocytes
AST: found in many sources- Liver, heart, intestine,
pancrease
Alkaline phosphatase: found in liver, bones,
intestines, and placenta
Bilirubin: Two sources- indirect (old red cells),
Direct (conjugated in liver)
Patterns
 Elevation in ALT & AST: primarily cellular injury
 Etiology: Acute Viral Hepatitis, Acetaminophen toxicity, shock
liver
 Elevation in Alk Phos and Bilirubin: cholestasis or
obstruction
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Etiology: choledocholithiasis, biliary stricture, malignancy
 Mixed: Serum Bilirubin can be elevated in both
conditions
Pearls for further evaluation
 Albumin
 Low Albumin- suggests chronic process (cirrhosis/cancer)
 Normal- suggests acute process
 Prothrombin
 Prolonged
suggests vitamin K deficiency 2/2 prolonged jaundice or
malabsorption
 Significant hepatocellular dysfunction (failure to correct w/ vit K
administration indicates severe injury)
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 Bilirubin in Urine
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Indicates hepatobiliary disease (indirect not excreted by kidney)
Mild Aminotransferase Elevation Workup
 Primary Causes
 Screen for alcohol abuse (AST/ALT > 2:1)
 Review medications

If Negative: then serology for hepatitis B/C, screen for
hemochromatosis, then evaluate for fatty liver w/ RUQ US
 Secondary
 Exclude muscle disorders
 Thyroid function tests
 Celiac disease
 Adrenal insufficiency
 IF All negative: Autoimmune, Wilson’s dx, alpha 1 antitrypsin, consider
biopsy or observe (pt w/ ALT/AST less that 2x ULN)
Hyperbilirubinemia
 Unconjugated
 Over production: hemolysis, extravasation of blood into tissue,
ineffective erythropoiesis
 Impaired Uptake: Heart failure, portosystemic shunts,
Gilberts, Drugs (Rifampicin and probenecid)
 Impaired conjugation: Gilberts, hyperthyroidism, Liver Dx,
Crigler-Najjar
 Conjugated
 Extrahepatic: choledocholithiasis, tumors, PSC, AIDS,
pancreatitis, strictures, parasitic infxn
 Intrahepatic: hepatitis, PBC, Drugs, Sepsis/hypoperfusion,
infiltrative disease, TPN, Sickle cell, pregnancy, Dubin
Johnson and Rotor Syndrome
Alkaline Phosphatase
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Source includes: bone, liver, placenta, varies w/ age
Serum GGT: elevated in Liver Disease not Bone disease
Most common cause: chronic cholestasis or infiltrative disease
Primary biliary cirrhosis, primary sclerosis cholangitis
 Sarcoidosis, amyloidosis, liver metastasis
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Initial Workup:
RUQ Ultrasound
 Anti-mitochondrial Antibody
 Consider- MRCP or ERCP
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Observe: if Alk phos <50% above normal
Elevation of Several LFT’s
 Hepatocellular pattern
 ALT/AST > 25 ULN only seen in hepatocullular dx
 With Jaundice
Alcholic
 AST:ALT.2
 AST rarely > 300 units/L
 Viral
 Aminotransferase> 500 u/L w/ ALT >AST
 Toxic: i.e. Acetaminophen
 Shock liver
 Autoimmune and Wilson’s Dx
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Elevation of Several LFT’s
 Predominantly Cholestatic Pattern
 Determine Intra vs Extra hepatic
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RUQ U/S: assess for Biliary dilation
 Extrahepatic: consider CT or MRCP or ERCP
 Common Causes: choledocholithiasis, malignancy, PSC,
Pancreatitis
 Intrahepatic: broad differential
 Work-up determined by clinic situation
Summary
 Described significance of each Liver function test
 Identified common LFT abnormalities
 Familiarized with basic initial work up of elevated
Liver function Tests