Liver “ Function ” Test

2013MINI-LECTURE

Liver “Function” Test

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 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 UltrasoundB: Hepatitis PanelC: Screen for Alcohol UseD: CT Scan Abdomen

Etiology

Synthetic Function: Total protein, serum albumin, total bilirubin, prothrombin time

ALT: found primarily in HepatocytesAST: found in many sources- Liver, heart,

intestine, pancreaseAlkaline phosphatase: found in liver, bones,

intestines, and placentaBilirubin: 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 liverElevation in Alk Phos and Bilirubin:

cholestasis or obstruction Etiology: choledocholithiasis, biliary stricture,

malignancyMixed: Serum Bilirubin can be elevated in

both conditions

Pearls for further evaluationAlbumin

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)

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-NajjarConjugated

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

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

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

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, PancreatitisIntrahepatic: 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