Liver Function and LFTs Flashcards
Each lobule is composed of what?
Hepatocytes arranged in plates, in contact with bloodstream on one side and bile canaliculi on the other. Between plates are vascular spaces (sinusoids) containing Kupffer cells
Briefly describe the functions of the liver
- Metabolic functions,
- Storage (glycogen, vitamins and iron),
- Protective (detoxification and elimination of toxic compounds, Kupffer cells ingest bacteria and foreign material from blood),
- Bile production and excretion ( formed in biliary canaliculi)
Describe the classification of liver disease?
- Infection,
- Toxic/Drug induced,
- Autoimmune,
- Biliary tract obstruction,
- Vascular,
- Metabolic,
- Neoplastic
What are some of the causes and potential outcomes of acute hepatitis
Causes - Poisoning (paracetamol), Infection (Hepatitis A-C) and inadequate perfusion.
Outcomes - Resolution, progression to acute hepatic failure and progression to chronic hepatic damage
What are some of the common and uncommon causes of chronic liver disease?
Common - Alcoholic fatty liver, chronic active hepatitis and primary biliary cirrhosis.
Uncommon - Alpha-1 antitrypsin deficiency, haemochromatosis and Wilson’s disease
What is cholestasis?
It is a consequence of failure to produce or excrete bile which results in accumulation of bilirubin in the blood leading to jaundice.
What are some of the causes of cholestasis?
- Failure of hepatocytes (intrahepatic cholestasis),
- Obstruction of bile flow (extrahepatic cholestasis)
- Or both together
What occurs in liver failure?
- Inadequate synthesis of albumin leading to oedema and ascites,
- Inadequate synthesis of clotting factors resulting in bruising,
- Inability to eliminate bilirubin causing jaundice,
- Inability to eliminate nitrogenous waste such as ammonia which causes encephalopathy (neuro-psychiatric disorder)
Define haemochromatosis
an inherited condition where iron levels in the body slowly build up over many years.
What measures are in the fife standard LFT panel?
Albumin, ALT (Alanine Aminotransferase), ALP (Alkaline Phosphatase) and Bilirubin
What are the Pros and Cons of measuring albumin?
Pros - It is the main plasma protein which is produced by the livere. Therefore assesses liver synthetic function.
Cons - Low albumin also found in post surgical/ITU patients, Patients with significant malnutrition and nephrotic syndrome
What are the Pros and Cons of measuring ALT?
Pros - It is a cytoplasmic enzyme which are sensitive markers of acute damage to hepatocytes.
Cons - Non specific as it is also found in cardiac muscles and erythrocytes. Therefore can also be raised in skeletal muscle disorders or myocardial infarction
What are the Pros and Cons of measuring alkaline phosphatase?
Pros - Used to look for biliary epithelial damage and obstruction. It is increased in liver disease.
Cons - ALP isoenzymes are also present in bone, gut and placenta so is raised in physiological states (pregnancy and childhood), when a bone is broken/disease and it can be induced by some drugs
What are the Pros and Cons of measuring Gamma-glutamyl transferase (Gamma GT)
Pros - Used to look for biliary epithelial damage and obstruction and is super sensitive.
Cons - Also present in bone, biliary tract, pancreas and kidney. It can be effected by ingestion of alcohol and some drugs. It may be over sensitive (on request not on LFT panel)
What are the pros and cons of measuring bilirubin?
Pros - Breakdown product of haemoglobin. Conjugated bilirubin is taken up by liver and conjugated bilirubin is excreted in bile. Therefore used as indicator of cholestasis.
Cons - It is also raised in haemolysis and hereditary hyperbilirubinaemias eg, Gilbert’s disease
