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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.
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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 • 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
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)
Patterns • Elevation in ALT & AST: primarily cellular injury • Etiology: Acute Viral Hepatitis, Acetaminophen toxicity, shock liver • Elevation in AlkPhos 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, 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