LFT's Flashcards
What are Kupffer cells?
Phagocytic macrophages
What are the 4 metabolic functions of the liver?
- Carbohydrates
- Hormones
- Lipids
- Drugs
- Proteins
What 3 things does the liver store?
- Glycogen
- Vitamins
- Iron
What are the 2 protective functions of the liver?
- Detoxification and elimination of toxic compounds
2. Kupffer cells ingest bacteria & other foreign material from blood
List the 7 classifications of liver disease?
- Infection- Viral (Hepatitis A-E, CMV), bacterial, parasitic
- Toxic/Drug induced
- Autoimmune
- Biliary tract obstruction-Tumours, gallstones
- Vascular
- Metabolic- haemochromatosis, Wilson’s, hereditory hyperbilirubinaemias
- Neoplastic
What is Cholestasis?
Failure to produce or excrete bile
What is Intrahepatic cholestasis?
Problems in secretion of bile by hepatocytes due to damage
What is Extrahepatic cholestasis?
Problems with flow of bile out of the liver due to obstruction
What does cholestasis result in?
- Accumulation of (conjugated) bilirubin in the blood leading to Jaundice
- Urine darkens and stool lightens
What can Jaundice also be due to?
Excessive haemolysis- bilirubin is unconjugated and does not appear in the urine
What is acute hepatic failure?
Development of severe hepatic dysfunction within 24 wks of onset of disease
Give 3 examples of acute hepatitis causes?
- Poisoning (paracetamol)
- Infection (Hepatitis A-C)
- Inadequate perfusion
What are the 3 common causes of chronic liver disease?
- Alcoholic fatty liver
- Chronic active hepatitis
- Primary biliary cirrhosis
What are the 3 unusual causes of chronic liver disease?
- Alpha-1 AT deficiency
- Wilson’s disease
- Haemochromatosis
What are the 4 possible consequences of chronic liver disease?
- Cirrhosis
- Portal hypertension
- Ascites
- Renal failure
What can portal hypertension lead to?
- Haemorrhage of oesophageal / gastric varices
- Hepatic encephalopathy (detoxifying function bypassed)
- Hypersplenism
- Decreased resistance to infections
What are ascites?
Accumulation of fluid in the peritoneal cavity
What 4 things does liver failure result in?
- Inadequate synthesis of albumin
- Inadequate synthesis of clotting factors
- Inability to eliminate bilirubin
- Inability to eliminate nitrogenous waste
What is hepatic encephalopathy?
Poorly defined neuro-psychiatric disorder that occurs when products normally metabolised by the liver accumulate in the systemic circulation
How can ammonia accumulate in the systemic circulation?
Decreased liver capacity to synthesize urea and glutamine in liver failure means the ammonia is no longer adequately metabolised and accumulates in the systemic circulation
List the 5 liver function tests?
- Aminotranferases (ALT & AST)
- Bilirubin
- ALP
- Gamma-GT
- Albumin
What does Albumin show?
Liver synthetic function
Under what 5 circumstances can albumin levels be low?
- Post-Surgical/ITU patients due to redistribution
- Significant malnutrition
- Nephrotic syndrome
- Burns
- Liver disease
What is bilirubin?
Breakdown product of haemoglobin
Describe the development and destruction of bilirubin?
- Unconjugated & taken up by liver and conjugated
- Conjugated bilirubin excreted in bile
- Attacked by bacteria in colon and excreted in faeces
- Small amounts reabsorbed & excreted in urine as urobilinogen
What is AST & ALT enzymes a marker of?
Sensitive, non specific markers of acute damage to hepatocytes
What is ALP enzyme a marker of?
Increased in liver disease due to increased synthesis in response to cholestasis
What is gamma-GT enzyme a marker of?
Raised in cholestasis, also affected by ingestion of alcohol and drugs such as phenytoin
Where else, other than the liver, is ALT found?
- Cardiac muscle
- Erythrocytes
Where else, other than the liver, is ALP found?
- Bone
- Gut
- Placenta
Where else, other than the liver, is gamma-GT found?
- Bone
- Biliary tract
- Pancreas
- Kidney
When can bilirubin be increased in the asymptomatic patient?
- Haemolysis
- Gilberts syndrome
When can ALP be increased in the asymptomatic patient?
- Pregnancy
- Adolescence
When can AST be increased in the asymptomatic patient?
- Skeletal muscle disorders
- MI
When can gamma-GT be increased in the asymptomatic patient?
- Alcohol
- Drugs
Describe LFT’s in acute hepatocellular damage?
- Bilirubin= RAISED
- ALT= RAISED
- ALP= NORMAL/ RAISED
- Gamma-GT= NORMAL/ RAISED
Describe LFT’s in chronic hepatocellular damage?
- Bilirubin= NORMAL/ RAISED
- ALT= NORMAL/ RAISED
- ALP= NORMAL/ RAISED
- Gamma-GT= NORMAL/ RAISED
Describe LFT’S in cholestasis?
- Bilirubin= RAISED
- ALT= RAISED
- ALP= RAISED
- Gamma-GT= RAISED
What is the most common LFT result from acute cholecystitis?
Increased ALP
What are the clinical signs of post-hepatic jaundice?
Dark urine & foul smelling pale stools which float
What are the clinical signs of pre-hepatic jaundice?
Normal urine and stools
What is the most important LFT change in hepatocellular jaundice?
Increased ALT
What is the most important LFT change in cholestatic (obstructive) jaundice?
Increased ALP
What are 4 possible causes of pre-hepatic jaundice?
- Haemolysis
- Haemolytic anaemia
- Rhabdomylosis
- Unconjugated bilirubinaemia
What are 3 possible causes of intrahepatic cholestasis?
- Tumours
- Drugs
- Virus giving acute hepatocellular damage
What are 3 possible causes of extra hepatic cholestasis?
- Gallstones
- Cancer of the head of pancreas
- Cancer of biliary tree
If ALT>AST what does this indicate?
Chronic liver disease
If AST>ALT what does this indicate?
Cirrhosis and acute alcoholic hepatitis
