Flashcards in Diseases of the liver and pancreas Deck (49)
Which organelle conjugates bilirubin?
Smooth endoplasmic reticulum
What are the functions of the liver?
- Glycogen storage & synthesis
- Glycolysis & gluconeogenesis
- Synthesis & catabolism
- Clotting factors
- Amino acid metabolism &urea synthesis
- Lipoprotein & cholesterol synthesis
- Fatty acid metabolism
- Bile acid synthesis
Excretion & detoxification
- Bile acid & bilirubin excretion
- Drug detoxification & excretion
- Steroid hormone inactivation & excretion
- Iron storage
- Vitamin A, D, E & B12 storage & metabolism
What is measured by LFTs?
ALT (alanine aminotransferase)
AST (aspartate transaminase)
GGT (glutamyl transferase)
What tests might be used for specific liver functions?
- prothrombin (clotting factors)
- bile acids
Excretion and detoxification
- steroid hormones
- Ferritin (iron storage)
- Prothrombin time (Vit K)
What tests give an indication of hepatocyte damage?
- Found in the cell and only released by cellular damage.
ALT is more specific for liver than AST
AST also found in muscle and red blood cells
Tumour markers – α-fetoprotein (primary hepatocellular carcinoma)
What tests give an indication of biliary tract damage?
Impaired excretory function
- Increased Conjugated bilirubin
Increased synthesis of enzymes by cells lining the bile canaliculi
What might be the causes of increased ALP in biliary tract damage?
Cholestasis (intra- or extrahepatic)
Space-occupying lesions (tumours)
Which organs also secrete ALP isoenzymes?
If γGT and ALP are raised, what might this mean?
A raised γGT supports a liver source of ALP (as opposed to any other isoenzyme).
Elevated due to structural damage
What can cause biliary tract damage?
enzyme inducing agents
- e.g. anti-epileptics
- e.g. due to alcohol, diabetes or obesity
- acute & chronic pancreatitis, cancer
- ARF, nephrotic syndrome, rejection
What are the biochemical markers of fibrosis?
- Hyaluronic acid
What is bilibrubin a measure of?
Excretory capacity of the liver and free flow of bile.
What is bilirubin measured as?
- Pre-hepatic & Hepatic
- Post-hepatic (Obstructive) & Hepatic
What serum level of bilirubin is considered to be jaundice?
> 40-50 μmol/L
What happens to bilirubin in the liver?
It is conjugated to bilirubin glucuronide by glucuronyl transferase.
What protein is bilirubin bound to in the blood?
What are the pre-hepatic causes of jaundice?
- e.g. Rhesus incompatibility
- e.g. spherocytosis
What are the post-hepatic (obstructive) causes of jaundice?
- i.e. cholangiocarcinoma, head of pancreas
What are the hepatic causes of jaundice?
- Inherited disorders of conjugation e.g. Gilberts, Crigler-Najjar
- Post-microsomal/impaired excretion
- Intrahepatic obstruction
- Inherited disorders of excretion e.g. Dubin-Johnson, Rotor.
What are the inborn errors of bilirubin metabolism?
Decreased activity of UDP glucuronyl transferase
Reduced ability to excrete bilirubin glucuronide
What is the pathway from haemoglobin to bilirubin glucuronide?
Haemoglobin -> bilirubin albumin-bound bilirubin -> bilirubin -> bilirubin glucuronide -> bile duct
The patient is jaundiced, their AST/ALT is elevated and their ALP is normal. What will are they likely to have?
Approx 90% of these patients will have hepatitis
The patient is jaundiced, their AST/ALT is normal and their ALP is elevated. What will are they likely to have?
Approx 90% will have obstructive jaundice
What will urine tests show in prehepatic jaundice?
Unconjugated bilirubin - no urinary bilirubin
What will urine tests show in hepatic jaundice?
Variable depending on degree of obstruction due to either disease or inflammatory oedema
What will urine tests show in post-hepatic jaundice?
Dark urine (&pale stools)
What are the systemic effects of liver disease?
- spider naevi
- liver palms
- testicular atrophy
osteomalacia / osteoporosis
What specific tests can be used in chronic active and autoimmune hepatitis?
Anti smooth muscle, anti liver/kidney, anti microsomal and anti nuclear antibodies
What test can be used for primary biliary cirrhosis?
Anti mitochondrial antibodies