19 measuring liver function Flashcards
What do LFTs involve?
Detecting the levels of several biochemical markers in the bloodstream
What substances are measured in LFTs?
- Bilirubin
- ALT
- AST
- GGT
- ALP
- protein
- albumin
- globulins
How do liver enzymes indicate liver disease?
They leak into the blood when liver cells are damaged
What do ALP and GGT show>
Suggest the presence of obstructive biliary disease
What is hepatitis?
Inflammation of the liver as a result of viral infection or harmful substances
What is cholestasis?
When bile cannot flow from the liver to the duodenum (mechanical vs metabolic)
What is cirrhosis?
Scarring of the liver as a result of the continuous, long-term liver damage
What is bilirubin?
A breakdown product released when RBCs are destroyed at the end of their 120 life span
How is unconjugated blood carried?
In albumin to the liver
How is conjugated blood carried?
It is excreted in bile as it is water soluble
What is the healthy level of bilirubin?
<20mmol/L
What happens at 35mmol of bilirubin?
The patient is jaundiced
What does conjugated bilirubin> unconjugated mean?
Biliary obstruction
What is likely if proportions of conjugated and unconjugated bilirubin are equal?
Hepatocellular damage is likely
How is conjugated bilirubin measured?
Urine sampling over 24 hours
What is palmer erythema?
Reddening of the skin on the palm
What is ascites?
Excessive accumulation of fluid in the abdominal cavity
What is spider naevi?
A type of swollen blood vessel
How much fluid is required for ascites to be detected by clinical examination?
1500ml
What are the symptoms of ascites?
Discomfort, nausea and appetite suppression and increasing dyspnoea
What is haemolytic jaundice?
Haemolytic of RBCs causing formation of bilirubin at a faster rate than liver can excrete
What causes haemolytic jaundice?
Drugs, infection and enzyme deficiency
What is the bilirubin amount in haemolytic jaundice?
80mmol/L
What is hepatocellular jaundice?
Due to damage of hepatocytes intracellular enzymes leak into the circulation and bilirubin is unable to be transported into the bile by hepatocytes
What causes hepatocellular jaundice?
- Infection
- drugs
- alcohol
- impaired blood supply
What is the bilirubin amount in hepatocellular jaundice?
Up to 300mmol
What are the 2 cholestasis jaundice?
- Intra-hepatic where there is failure of bile flow/excretion within the liver
- extra-hepatic where there is obstruction of the biliary tree outside the liver
What is the bilirubin amount in cholestasis jaundice?
Up to 500mmol/L
What do high ALT levels indicate?
acute liver disease
What do moderately raised levels of ALT indicate?
acute liver disease
What does low ALT suggest?
Vitamin B6 deficiency
Where is AST found?
In the liver, heart, kidneys, skeletal muscle and RBCs
When are AST levels raised?
In shock, pregnancy and after exercise
What is GGT used for?
Identifying patients at risk of liver disease due to alcoholism
When is ALP raised?
In cirrhosis and liver cancers as well as bone diseases
Are albumin levels high or low in chronic liver disease?
Low
When are albumin levels reduced?
- malnutrition
- chronic renal failure
- nephrotic syndrome and severe burns
- in surgery
- pregnancy
- with age
- when over hydrated
What is prothrombin time?
a measure of time taken for blood to clot and to check for bleeding problems
How is PT affected by chronic liver conditions?
It is raised from 10-14 seconds
What does increased bilirubin indicate?
loss of function of bile ducts
