liver “ function ” test
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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. - PowerPoint PPT PresentationTRANSCRIPT
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 liver
Elevation in Alk Phos and Bilirubin: cholestasis or obstruction 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)
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-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
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