Liver Function Tests Flashcards
State the 5 serum markers of liver cell damage
Alanine aminotransferase (ALT), Aspartate aminotransferase (AST), alkaline phosphatase (ALP), gamma-glutamyl transferase (GGT), bilirubin
State the 3 serum markers of synthetic liver function
INR, albumin, glucose
Where is AST found?
Liver, heart, skeletal muscles, kidneys, brain
What is the typical ratio of AST to ALT in alcoholic hepatitis?
2:1
Where is ALT found?
Primarily in the liver
What is the typical ratio of AST to ALT in viral hepatitis?
1:1
Where is ALP found?
Liver, bones, placenta
What are the main causes of a raised ALP?
Cholestasis, bone disease, pregnancy
Where is GGT found?
Hepatocytes, biliary cells, kidneys, pancreas
What are the main causes of a raised GGT?
Alcoholism, bile duct disease, liver metastases
How much albumin does the average adult synthesise per day?
200mg/kg
Which clotting factors does the liver synthesise?
Factors V, VII, IX, X, XII, XIII, fibrinogen, prothrombin
What is the INR?
Internal normalised ratio: The prothrombin time (PT) standardised for age and population and expressed as a ratio of normal
State three causes of deranged clotting other than liver disease
Iatrogenic (e.g. warfarin), hereditary thrombophilia, acquired consumption (e.g. disseminated intravascular coagulation)
What is jaundice?
Elevated serum bilirubin causing yellowing of the skin and sclera
Describe the normal metabolism of bilirubin
Bilirubin is released from red blood cell breakdown, transported to the liver, conjugated in hepatocytes, secreted into the bile ducts and then GI tract, metabolised into urobilinogen, partially reabsorbed by the kidneys which excrete it as urobilin, and partially converted into stercobilin (the brown pigment in faeces)
Describe the laboratory findings in pre-hepatic jaundice
Elevated unconjugated bilirubin, reduced haemoglobin, reduced haptoglobin, raised LDH
State two causes of pre-hepatic jaundice
Haemolysis, congestive heart failure
Describe the laboratory findings in hepatic jaundice
Elevated unconjugated bilirubin, raised aminotransferases, may be synthetic dysfunction
State three causes of post-hepatic jaundice
Biliary tree obstruction (e.g. stones, strictures, inflammation), pancreatic cancer, cholangiocarcinoma
Describe the laboratory findings in post-hepatic jaundice
Elevated conjugated bilirubin, elevated urine bilirubin
