The document discusses liver function tests and their significance. It describes the patterns that different disease states can produce in liver enzyme levels and bilirubin. For the case presented with elevated AST and ALT, the next step in management would be an RUQ ultrasound to identify any underlying liver abnormalities. The document provides guidance on evaluating common causes of liver enzyme and bilirubin elevations and determining appropriate further workup and testing.

1. 2 0 1 3
M I N I - L E C T U R E
Liver “Function” Test

2. Objectives
 Understand the significance of Liver Function Tests
 Identify the patterns that indicate specific disease
categories
 Identify the appropriate further work up of
abnormalities

3. Case
 49 year old Female presents with chest pain and
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

4. Etiology
 Synthetic Function: Total protein, serum albumin,
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)

5. 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
 Etiology: choledocholithiasis, biliary stricture, malignancy
 Mixed: Serum Bilirubin can be elevated in both
conditions

6. 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)
 Bilirubin in Urine
 Indicates hepatobiliary disease (indirect not excreted by kidney)

7. 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)

8. 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

9. Alkaline Phosphatase
 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
 Initial Workup:
 RUQ Ultrasound
 Anti-mitochondrial Antibody
 Consider- MRCP or ERCP
 Observe: if Alk phos <50% above normal

10. 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

11. Elevation of Several LFT’s
 Predominantly Cholestatic Pattern
 Determine Intra vs Extra hepatic
 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

12. Summary
 Described significance of each Liver function test
 Identified common LFT abnormalities
 Familiarized with basic initial work up of elevated
Liver function Tests