Liver Biochemistry And Liver Function Tests Flashcards
To learn about LFTs
What are the liver function tests?
- Plasma bilirubin
- Albumin
- Alanine transaminase
- Aspartate transaminase
- Alkaline phosphatase
What do biochemical measures of liver function assess?
Hepatic anion transport: principally serum bilirubin, less than 5% of serum bilirubin is normally conjugated.
In measuring abnormal protein synthesis what factors are taken into consideration?
- Serum albumin: hypoalbuminaemia in chronic liver injury
In measuring abnormal protein synthesis what factors are considered?
Prothrombin time: maybe increased due to failure to absorb fat soluble vit K, In cholestasis factors II (prothrombin), VII, IX and X are bit K dependant; or from impaired synthesis of coagulation factors- as above plus factor V and fibrinogen. Raised prothrombin time corrected by giving parenteral vitamin K
In measuring abnormal protein synthesis what factors are considered?
Serum immunoglobulins usually increased in chronic liver disease:
- IgM inc in primary biliary cirrhosis.
- IgG inc in chronic autoimmune hepatitis
What do liver function tests assess, in relation to the cytoplasmic and mitochondrial enzymes?
Cytoplasmic and mitochondrial enzymes:
- Raised in hepatocellular damage
- ALT is more liver specific than AST and raises more than AST in early hepatocellular injury.
- AST is raised more in chronic injury.
What do liver function tests assess in relation to membrane associated enzymes?
- ALK and gamma glutamyl transferase are anchored to the the biliary canuliculus.
- Raised in biliary outflow obstruction rather than damage
What is jaundice?
- Describes yellow staining of the tissues due to xs bilirubin.
- Normal serum bilirubin is 3-17microm/l.
- Jaundice detectable > 40microm/l.
What is raised bilirubin the result of?
- Raised excretion or raised production
- Raised production result of obstruction
- ALK/¥GT increased
- In mech obstruction more than 50% of the bilirubin is conjugated
Explain pre- hepatic bilirubin metabolism?
- Haemoglobin broken down to amino acids and haem.
- Then cleaved by haem oxygenase to give CO, FE and bilverdin.
- Biliverin converted to bilirubin.
- Bilirubin carried by albumin coz not soluble in water.
If bilirubin not taken up by liver or produced in xs what happens?
Unconjugated bilirubin deposited in tissues causing prehepatic jaundice.
What is Hepatic jaundice?
Failure in the function of hepatocytes to take up, metabolize or excrete bilirubin.
What are the clinical signs of Hepatic jaundice?
- Comes on rapidly
- Orange tint
- Fatigue and malaise
- Serum transaminases increased
- Serum albumin reduced
- PT time inc and doesn’t fall with Vit K
Describe post hepatic bilirubin metabolism?
- Bilirubin is converted to urobillinogen then to urobilin which colours faeces.
- Alternatively conjugated bilirubin can be acted upon bacteria in gut to give bile pigment stercobilin.
- Failure of bilirubin to reach gut due to obstruction results in reduction of pale stools.
What are possible causes of raised plasma alkaline phosphatase?
- Hepato-biliary disease
2. Bone disease
What hepato-biliary diseass cause raised ALK?
- Cholestasis: Elevation of ALP >10×
2. Hepatocyte diaeasel: viral hep, moderate rises in ALK
What bone diseases cause raised ALK?
- Paget’s disease
- Osteomalacia/rickets
- Vitamin D deficiency
- Profile of serum Ca, Pho and ALK helpful to diag vit D def
- Renal osteodystrophy
- Bone metastases
What are the signs and symptoms of acute liver disease?
- Anorexia
- Nausea and vomiting
- Intolerance of food, alcohol and cigarettes
- Skin itch
- Right upper quadrant pain
As jaundice appears and liver disease is advancing what other symptoms maybe noticed?
- Peripheral selling
- Abdominal swelling
- Bruising
- Vomiting of blood
- Confusion and somnolence
What is the differential diagnosis for patients presenting with right upper quadrant pain?
- Biliary pain: rapidly increases, then plateaus
- Acute cholecystitis: >6 hours, fever, leucocytosis
- Dyspepsia: bloating, nausea, int fatty foods
- Duodenal ulcer: pain 2hrs after meal, relieved by food and antacids
- Hepatic abscess: pain, fever, chills palpable liver, subcostal tenderness
- Acute MI: Right upper quad pain, epigastric pain
- Duodenal ulcer
- Acute pancreatitis
- Pneumonia
- Subphrenic abcess
What is Cholecystitis?
- inflammation of the gallbladder
- Most common cause is gallstones 95%
- May result from trauma, surgery, infection and parenteral nutrition
What are the clinical features of Cholecystitis?
- Pain in upper right quadrant
2. Nausea, vomiting, fever
What are the possible signs of Cholecystitis?
- Tenderness over right upper quadrant
- Tenderness over gallbladder on insp
- Boas sign hyperaethesia below scapula
- Gall bladder palpable
- Murphy’s sign
What investigations relate to Cholecystitis?
- FBC: usually a leucucytosis
- LFTs: to detect obstructive jaundice
- ABX: Air in biliary tree, rarely shows opaque stones
- US
- MRI cholangiopancreatography
- CT
What us the management of acute Cholecystitis?
- Bed rest, gut rest, analgesia, anti emetics IV fluids and antibiotics
- IV co amoxiclav
- Oral co amoxiclav
- Surgical
What are the complications of Cholecystitis?
- Empyema
- Gangrenous Cholecystitis
- Perforation of gallbladder
- Emphysematous Cholecystitis
- Pancreatitis
- Perihepatic Abscess
- Portal pyaemia and septicaemia
What three classes of liver disease present from urinalysis?
- Obstructive jaundice
- Hemolytic jaundice
- Compensated hepatic cirrhosis
How does urinalysis show obstructive jaundice?
- Urine is initially dark but becomes green
- Positive for bilrubin
- Negative for urobilnogen
How does urinalysis show haemalytic jaundice?
- Urine normal but darkens on standing
- Negative for bilirubin
- Positive for urobilnogen
How does urinalysis show compensated hepatic cirrhosis?
- Negative for bilrubin
2. May be positive for urobilnogen due to failing liver not adequately metabolising normal qty of reabsorbed urobilnogen
What is a typical liver screen?
- LFTs inc ¥GT and total protein
- Ethanol
- Coag tests, incl INR and APTT
- Hepatitis serology- for A,B and C
- Viral screen - CMV, EBV etc
- Ferritin and total iron binding
- Alpha 1 antitrypsin
- Immunoglobulins and protein electro phoresis
- Autoantibody screen
- alpha-feto protein ( tumour markers)
- Serum copper
What morphological changes give rise to Alcoholic Liver Diseases?
- Fatty change
- Alcoholic hepatitis
- Alcoholic cirrhosis