12. Liver function Flashcards
Functions of the liver (7)
1) acid/base balance
2) fluid and electrolyte homeostasis
3) detoxification
4) antimicrobial
5) clotting factors
6) protein synthesis
7) glycogen storage
Single most abundant serum protein
Albumin
What clotting factors does the liver synthesise?
2, 7, 9, 10
what antithrombotic factors does the liver synthesise?
Antithrombin III
protein C
protein S
Where is Carbamoylphosphate synthetase found?
all but last 1- 2 hepatocytes round terminal hepatic venule
ammonia metabolism
‘Fed’ state
liver synthesises glycogen from glucose
perivenular hepatocytes
‘Fasted’ state
liver synthesises glucose
periportal hepatocytes
Bile composition
Phospholipids
Cholesterol
Water
Inorganic electrolytes
Bile acids
Bile pigments
How much bile is excreted per day?
500ml – 600ml
What are primary bile acids synthesised from?
cholesterol in the liver
\What are secondary bile acids synthesised from?
degradation of primary bile acids by bacteria in the gut
What does bile acid conjugation do?
↓ passive diffusion
accumulation in gut lumen
facilitates fat digestion and absorption
Enterohepatic circulation of bile salts
Hepatocyte
Biliary tree
Small bowel
Enterocytes
Portal blood
Hepatocyte
How much of the bile salts are conserved in enterohepatic circulation?
90%
How many times does the bile acid pool circulates daily
5-15 times
Bilirubin metabolism
haem →biliverdin by Haemoxygenase
biliverdin → unconjugated bilirubin by Biliverdin reductase
What percentage of bilirubin is derived from haem released by breakdown of erythrocytes?
80%
Paracetamol overdose: clinical features
Fresh bruises
Liver flap
Abdominal pain
Mildly jaundiced
Patient is drowsy but obeying commands
Pear drops
Prothrombin time
A measure of clotting of the blood
Urea and electrolytes (U+Es)
Na, K, U, Creat
renal function and electrolyte balance
Liver function tests (LFTs)
AP, ALT, Bil, Alb
Reflect liver damage
pH
Measure of acid/base balance
Paracetamol overdose: management
Central venous access and fluid replacement
Arrange for transfer to FRH
N-acetyl cysteine administration
Transfer to ITU
Intubation and ventilation
Chronic liver failure: clinical presentation
Jaundice
Leuconychia
Clubbing
Palmar erythema
Gynaecomastia
Bleeding varices
ascites
umbilical hernia
dilated abdominal wall veins
Chronic liver failure: management
Banding of varices
Endoscopy
Vitamins/nutrition
Diuretics
Liver screen
Abdominal U/S
Sub-acute liver failure
development of encephalopathy within 5 - 12 weeks of the onset of jaundice
Hyper-acute liver failure
development of encephalopathy within 7 days of the onset of jaundice
What are the clinical abnormalities (signs) of acute liver failure?
0-24 hrs: Patient may appear well – however nausea + vomiting
48–72 hrs: Anorexia, Right subcostal pain
72hrs+: Jaundice, Encephalopathy, Cerebral oedema
Phase I of paracetamol OD
1 - 24 hours patient complains of nausea, vomiting and diaphoresis.
Phase II of paracetamol OD
24 - 48 hours there may be no symptoms or clinical evidence of liver disease
Phase III of paracetamol OD
2 - 10 days
overt liver disease
What causes jaundice seen in liver failure?
conjugation and excretion of bilirubin
What causes encephalopathy?
metabolism of ammonia and detoxification of benzodiazepine like compounds
What causes Ascites and oedema?
impaired synthesis of albumin
What causes bruising?
impaired synthesis of clotting factors
CAGE Questionnaire
Have you ever felt you should CUT down on your drinking?
Have you ever felt ANNOYED by people criticising your drinking?
Have you ever felt GUILTY about your drinking?
Have you ever had a drink first thing in the morning? As an EYE OPENER
Rigler’s sign
gas either side of the lumen
Small bowel obstruction
Dilated >3cm small bowel
Centrally placed
Valvulae conniventes are readily defined (coiled spring sign)
large bowel obstruction
calcification in the left kidney
Causes of liver Cirrhosis (5)
Chronic infection
Alcohol abuse
Biliary disease
Iron overload
Autoimmune hepatitis
Where is glutamine found?
Last 1-2hepatocytes
scavenge any remaining ammonia
