Liver Function Tests Flashcards
What are the symptoms of cirrhosis?
Jaundice and pruritus nausea and vomiting Hepatomegaly Ascites Dark urine and pale stools in cholestasis Spider nave in alcoholic liver disease
What are the causes of liver damage?
Viral hepatitis Alcohol abuse Obesity (cirrhosis) Cancer Adverse drug reaction
What adverse drug reactions can cause liver damage?
Halothane Paracetemol overdose Clavulanic acid in 'augmentin'- co-amoxiclav Valporate Amiodarone Herbals
How is Bilirubin produced?
Mainly from breakdown of RBCs
Iron and globing are reused, biliverdin is formed from haem and reduced to bilirubin
Bilirubin is uncongugated and water insoluble
The liver conjugates bilirubin to make it water soluble and excreted as bile
When is bilirubin increased?
Biliary obstruction (cholestasis)
Hepatocellular damage
Haemolysis
What are aminotransferases (AST/ALT)?
Leak out from damaged cells
Markedly raised in hepatocellular damage
ALT a more specific marker of liver damage
Increases >2 fold greater than upper limits are often associated with biopsy proven liver disease
What’s alkaline phosphate?
Present in canalicular and sinusoidal membranes of liver
(Also other tissues e.g bone and placenta)
Markedly raised in cholestasis
Raised in infiltration of liver e.g markedly in metastasis
What are Gamma GTs?
Microsomal enzyme present in many tissues including the liver
What increases Gamma GTs?
Induction: Alcohol Carbamazepine Barbiturates Phenytoin Rifampicin Cholestasis Cellular damage
What does albumin do?
Measures synthetic activity of liver
Indicate changes over a longer term
T1/2= 16-24 days
What is International Normalised Ratio (INR)?
Prothrombin time
Indicates synthetic activity (and coagulation)
As coagulation factors have a relatively short half life indicates both acute and chronic damage
Why are LFTs carried out?
Some diagnostic value
Poor predictor of drug metabolism
Monitor drug treatment
What drugs are monitored using LFTs?
Statins Fibrates Amiodarone Isotretinoin Rifampicin Glitazones Valporate Sulfasalazine
What are the LFT results for acute hepatitis?
ALT + AST: Increased ALP: Increased or normal Bilirubin: Increased or normal GGT: Increased or normal Albumin: Normal INR: Increased or normal
What are the LFT results for cholestasis?
ALP: Increased GGT: Increased Bilirubin: Increased ALT + AST: Normal or increased Albumin: Normal INR: Normal or increased (reduced Vit K absorption)
What are the LFT results for chronic liver disease?
GGT: Increased Bilirubin: Increased Albumin: Decreased INR: Increased ALP, ALT+AST: Normal or increased
What is jaundice?
Hyperbilirubinaemia resulting in yellow colouration of the skin and sclera of the eye
Leads to pruritus and nausea
What’s prehepatic jaundice?
Water insoluble unconjugated bilirubin produced faster than liver can conjugate for excretion
Open due to haemolysis- haemolytic anaemias (spherocytosis)
Gilbert’s syndrome- reduced levels of UDP-glucuronosyl transferase which conjugates bilirubin
What’s hepatocellular jaundice?
Transaminases leak out
Liver cannot convert insoluble bilirubin from the blood to water soluble bilirubin
Reduced bilirubin excretion (pale stools)
What’s cholestasis?
Bile cannot flow from the liver to the duodenum
What’s intrahepatic cholestasis?
Primary biliary cirrhosis: autoimmune damage to bile ducts
Hepatocellular damage
In pregnancy with unknown cause (3rd trimester)
What’s extrahepatic cholestasis?
Gallstones
Ca head of pancreas
What’s obstructive jaundice?
Cholestasis
GGT and ALP not excreted and are elevated
Liver can convert insoluble bilirubin in the liver to water soluble bilirubin
Cannot excrete bilirubin in the bile (pale stools)
Water soluble bilirubin excreted in the urine (dark urine)
What are the complications of liver disease?
Jaundice Ascites (accumulation of fluid in the peritoneal cavity) Encephalopathy Impaired coagulation Gastric bleeding Bleeding oesophageal varies
What causes ascites?
Oedema secondary to hypoproteinaemia
Sodium retention due to secondary hyperaldosteronism
Portal hypertension
What are the neuropsychiatric symptoms of encephalopathy?
Changes in personality Disorientation Confusion and drowsiness Sensitivity to centrally acting drugs Gut flora produces nitrogenous waste products, including ammonia
How do you treat encephalopathy?
Neomycin/metronidazole
Lactulose
What can be used to treat gastric bleeding?
Ranitidine
What can be used to treat bleeding oesophageal varices?
Beta blockers
Octreotide
