6 - LFTs and Jaundice Flashcards
What is the definition of jaundice?
Can be divided into prehepatic, hepatic and post hepatic
Where does bilirubin come from and how is it excreted?
- Breakdown product of haem
- Initially unconjugated and bound to albumin
- Conjugated in the liver so it is water soluble
- Excreted in urine and faeces
Within each category of jaundice, e.g prehaptic, what is the cause of the raised bilirubin?
What are some common causes of pre-hepatic jaundice?
- Increased degradation of Hb so increased demand on liver so raised levels of unconjugated bilirubin
Why does neonate jaundice need to be corrected?
- Raised levels of unconjugated bilirubin can pass BBB and damage brain
What are some common causes of hepatic jaundice?
Reduced conjugating ability of liver due to damaged hepatocytes so mixture of conjugated/unconjugated bilirubin
What are some common causes of post hepatic jaundice?
- Obstruction of excretory pathway so raised conjugated bilirubin
- Gall stones, biliary stricture, pathology of pancreatic head (e.g pancreatic carcinoma)
What are some symptoms of post hepatic jaundice?
- Pale stools and dark urine as more excreted in kidneys
What are some intrahepatic pathologies that can be classed as both hepatic and post hepatic jaundice?
- Oedema
- Primary or metastatic malignancy
- Scarring/Cirrhosis
All can compress the intrahepatic ducts
How is pancreatic carcinoma a cause of post hepatic jaundice?
- Growth of the head can lead to obstruction of duct
- Weight loss and jaundice
What are some tests we can look at to assess liver function?
- Conjugated/Unconjugated bilirubin
- Albumin
- ALT
- AST
- ALP
What blood tests can tell you about the synthetic function of the liver?
- Albumin: low in liver disease as synthesised here. can lead to ascites
- INR for clotting factors
What are markers of hepatocyte damage?
- Raised ALT and AST in the blood
- AST less specific as found in cardiac, skeletal and RBC
- ALT > AST in liver damage
- AST > ALT in cirrhosis and alcoholic hepatitis
What is ALP (alkaline phosphatase) a marker of and how can you distinguish between the two?
- Bone turnover
- Damage to biliary tree, e.g cholestasis, as found in cells lining the bile duct
- Use Gamma GT, if both this and ALP raised it is bile duct pathology, if gamma GT not raised other cause likely
What are the patterns LFTs can show?
- Obstructive
- Hepatocellular damage
- Mixed
- LFTs can be deranged and no jaundice and if jaundice LFTs can help identify the cause
What would be LFTs in each of the three types of jaundice?
What are some perianal pathologies that might be present in Crohn’s disease?
- Anal fissure
- Haemorrhoids
- Skin tags
- Perianal abscess
- Opening of a fistula
Why does weight loss occur in Crohn’s disease?
- Commonly affects the small intestine which is the site of nutrient absorption in the gut
- Inflammatory processes in the small intestine will reduce absorption of nutrients which will result in weight loss
In pre-hepatic jaundice the raised plasma bilirubin levels tend to be unconjugated despite normal liver function.
Briefly explain why.
How does saliva become hypotonic?
- More ions reabsorbed from saliva than secreted into saliva
- Ductal cells relatively impermeable to water
- Overall effect is more ions removed from saliva than water= hypotonic
What are the main features and processes that occur in the pharyngeal phase of swallowing?
What is a suitable investigation for dysphagia to solid foods?
- Barium swallow
- OGD
