Liver Function Tests Flashcards
What is the safe weekly alcohol limit?
0-21 units/wk for men
0-14 units/wk for women
Not drunk in 1/2 bouts
2-3 alcohol free days a week
What are the signs and symptoms of Liver Disease?
Jaundice and Pruritis Nausea/Vomiting Hepatomegaly Ascites Dark urine and pale stools (cholestasis) Spider naevi (alcoholic liver disease)
What is the major infective cause of liver damage?
Viral hepatitis
What are the major ADRs leading to liver damage?
Halothane Paracetamol overdose Clavulanic acid Valproate Amiodarone Herbals
What are the major lifestyle causes of liver disease?
Obesity
Alcohol abuse
What cancerous conditions lead to liver disease?
Primary cancer
Secondary metastases
What are the main factors measured in an LFT?
Hepatocellular
Obstruction
Synthetic Function
Bilirubin
What values are measured when assessing hepatocellular health?
Alanine Aminotransferases (<45 iU/L) Aspartate Aminotransferases (<50 iU/L)
What values are measured when assessing obstruction?
Alkaline Phosphatase (39-117 iU/L) Gamma-glutamyl transpeptidase/transferase (0-70 iU/L m, 0-40 iU/L f)
What values are measured when assessing synthetic function?
Albumin (30-48 g/L)
INR (1-1.2)
What are the normal values for Bilribuin?
5-17 umol/L
Describe Bilirubin physiology
Produced from breakdown of RBCs
Haem-Biliverdin-Bilirubin
Liver conjugates, makes water soluble
Excreted as bile
What is the main effect of increased levels of Bilirubin?
Jaundice
When are levels of Bilirubin increased?
Bilary obstruction (cholestasis)
Hepatocellular damage
Haemolysis
How is Bilirubin excreted?
5-10% as stercobilinogen in stools
Majority undergoes enterohepatic cycling
When are the Aminotransferases raised?
Markedly raised in hepatocellular damage
Which Aminotransferase is a more specific marker of liver damage?
Alanine Aminotransferase (ALT)
What do levels of ALT >2x greater than upper limits correspond with?
Biopsy proven liver disease
Where is Alkaline Phosphatase normally found?
Present in canalicular/sinusoidal membranes
When is Alkaline Phosphatase raised?
Markedly raised in Cholestasis
What are Gamma Glutyltransferases?
Microsomal enzymes present in many tissues
When is Gamma Glutyltransferase raised?
Increased by induction -Alcohol (even small amounts) -Carbamazepine -Barbiturates -Phenytoin -Rifampicin Increased in cholestasis Increased in cellular damage
What does Albumin represent?
Synthetic activity of Liver over the long term
What is the T1/2 of Albumin?
T1/2 = 16-24 days
What is the Prothrombin Time?
Measure of coagulation and synthetic activity
Does the Prothrombin Time indicate acute or chronic damage?
Both
Coagulation factors have a short half life
What LFT results would be typical of Acute Hepatitis?
ALT & AST - Increased ALP - Increased/Normal Bilirubin - Increased/Normal GGT - Increased/Normal Albumin - Normal INR - Increased/Normal
What LFT results would be typical of Cholestasis?
ALT & AST - Increased/Normal ALP - Increased Bilriubin - Increased GGT - Increased Albumin - Normal INR - Increased/Normal
What LFT results would be typical of Chronic Liver Disease?
ALT & AST - Increased/Normal ALP - Increased/Normal Bilirubin - Increased GGT - Increased Albumin - Decreased INR - Increased
What is Jaundice?
Hyperbilirubinaemia resulting in yellow colouration of the skin/sclera
What level of Bilirubin is found in Jaundice?
> 35-50 umol/L
What further symptoms develop from Jaundice?
Pruritis
Nausea
What is Prehepatic Jaundice?
Jaundice occuring when water insoluble, unconjugated Bilirubin is produced faster than the liver can conjugate it
What are the main causes of Prehepatic Jaundice?
Haemoylsis/Haemolytic anaemias
Gilbert’s Syndrome (reduced levels of UDP-glucuronosyl transferase)
What is Hepatocellular Jaundice?
Loss of transaminases
Liver unable to conjugate Bilirubin
Reduced Bilirubin excretion
What is Cholestasis?
Disorder where Bile cannot flow from the liver to the duodenum
What are the two types of Cholestasis?
Intrahepatic
Extrahepatic
Describe Intrahepatic Cholestasis
Cholestasis occurring within the liver
- Primary bilary cirrhosis (autoimmune damage to bile ducts)
- Hepatocellular damage
- Pregnancy w/ unknown cause
Describe Extrahepatic Cholestasis
Cholestasis occurring outside the liver
- Gallstones
- Calcified head of pancreas
Describe Obstructive Jaundice
Jaundice caused by cholestasis
Liver CAN convert insoluble-soluble bilirubin
CANNOT excrete bilirubin in bile, only in urine
What are the signs/symptoms of Obstructive Jaundice?
GGT & ALP - Elevated
Pale stools
Dark urine
Bilirubin in urine
What are the most common complications of liver disease?
Jaundice
Ascites
Encephalopathy
How does Jaundice present?
Nausea
Pruritis
How should Jaundice be treated pharmacologically?
Colestyramine
How does Ascites present?
Accumulation of fluid in the peritoneal cavity
- Oedema
- Sodium Retention
- Portal Hypertension
How should Ascites be treated?
Sprinolactone + Furosemide + salt restriction
How does Encephalopathy present?
Changes in personality
Disorientation
Confusion/drowsiness
How should Encephalopathy be treated?
Neomycin/Metronidazole + Lactulose
What are less common complications of liver disease?
Impaired coagulation Gastric bleeding (Ranitidine) Bleeding oesophageal varices (B-Blockers, Octreotide)
