Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Y4 Gastrointestinal > LFT's > Flashcards

LFT's Flashcards

1
Q

What are the main synthetic functions of the liver ?

A
  • Conjugation and elimination of bilirubin
  • Synthesis of albumin
  • Synthesis of clotting factors
  • Gluconeogenesis
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What investigations are mainly done to assess the synthetic function of the liver ?

A
  • Serum bilirubin
  • Serum albumin
  • PT/INR
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What type of jaundice cases prolonged PT/INR and why?

A
  • Liver is responsible for synthesis of most clotting factors.
  • When there is reduced synthetic function of the liver it therefore doesnt produce these factors as well and results in prolonged PT/INR
  • ==> in the absence of other potential causes of a prolonged PT/INR then it suggests an intrahepatic pathology
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are the other causes of a prolonged PT/INR besides intrahepatic pathology ?

A
  • Anti-coagulant drugs (inc Warfarin)
  • Bile malabsorption causing relative Vit K deficiency
  • Consumptive coagulopathies
  • Congenital coagulopathy
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What are the enzymes produced by the liver ?

A
  • AST & ALT
  • ALP
  • gamma-GGT
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is AST/ALT and what do they usually represent ?

A

These are hepatic enzymes that are usually intracellular, but when the liver is damaged they are released from hepatocytes ==> become raised when liver is damaged

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Which is better for assessing liver damage AST or ALT ?

A

ALT because it is specific to the liver whereas AST can be increased due to other disorders as it is also present in the heart, pancreas, skeletal muscle, lungs, RBC’s & WBC’s

==> ALT is the most useful marker of hepatocellular injury

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Where does ALP originate and ==> what is it a useful marker of ?

A
  • ALP is particularly concentrated in the liver, bile duct and bone tissues.
  • It is a useful marker of intrahepatic and post-hepatic jaundice - in particular tho for post-hepatic jaundice

Note it can also be increased in bone disease, during pregnancy, and certain malignancies

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

List the causes of a solo raised ALP

A
  • Bony metastases / primary bone tumours (e.g. sarcoma)
  • Vitamin D def
  • Recent bone fractures
  • Renal osteodystrophy
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Define what jaundice is

A

This is yellowing of the skin and sclera

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What causes jaundice ?

A

It results from high levels of bilirubin in the blood.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What levels of bilirubin usually result in jaundice ?

A

usually >40 umol/l

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is bilirubin the normal breakdown product of ?

A

Haemoglobin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Describe the normal breakdown pathway and excretion of bilirubin

A
  1. Normally haemoglobin is broken down into unconjugated bilirubin
  2. It is then goes to the liver where it undergoes conjugation (to make it water soluble)
  3. Conjugated bilirubin is then excreted via the bile into the GI tract (as urobilinogen and stercobilin) which is then excreted out of the body

Around 10% of urobilinogen is reabsorbed into the bloodstream and excreted through the kidneys ==> bilirubin gives urines its darker colour

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What are the indices of intrinsic function of the liver ?

A
  • Albumin
  • PT/INR
  • Bilirubin
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What are the 3 main types of jaundice ?

A
  1. Pre-hepatic
  2. Hepatocellular (hepatic)
  3. Post-hepatic.
17
Q

What is the underlying pathogenesis of pre-hepatic jaundice ?

A
  • There is excessive RBC breakdown which overwhelms the liver’s ability to conjugate bilirubin.
  • This causes an unconjugated hyperbilirubinaemia.
  • Any bilirubin that manages to become conjugated will be excreted normally, yet it is the unconjugated bilirubin that remains in the blood stream to cause the jaundice.
18
Q

List the potential causes of pre-hepatic jaundice

A

Increased bilirubin production:

  • Extra/intravascular haemolysis
  • Extravasation of blood into tissues

Impaired hepatic bilirubin uptake:

  • Heart Failure
  • Drugs; Rifampicin, Probenecid

Impaired bilirubin conjugation

  • Gilbert’s/Crigler-Najjar Syndrome
  • Hyperthyroidism
  • Advanced Liver Disease
19
Q

What is the underlying pathogenesis of pre-hepatic jaundice ?

A
  • There is dysfunction of the hepatic cells. The liver loses the ability to conjugate bilirubin (acute hepatocellular injury)
  • In other cases it may become cirrhotic, where it compresses the intra-hepatic portions of the biliary tree causing a degree of obstruction. This leads to both unconjugated and conjugated bilirubin in the blood, termed a ‘mixed picture’. (chronic hepatocellular injury)

For simplisity know that intrahepatic causes a conjugated hyperbilirubinaemia

20
Q

List the causes of intrahepatic jaundice

A

Causes of acute hepatocellular injury include:

  • Poisoning (paracetamol overdose)
  • Infection (Hepatitis A and B)
  • Liver ischaemia

Causes of chronic hepatocellular injury include:

  • Alcoholic fatty liver disease
  • NAFLD
  • Chronic infection (Hepatitis B or C)
  • Primary biliary cirrhosis
  • Others; alpha-1 antitrypsin deficiency, Wilson’s disease, Haemochromatosis
21
Q

What is the underlying problem causing all post-hepatic jaundice (obstructive)?

A

There is obstruction of biliary drainage stopping conjugated bilirubin being both excreted out in the faeces and urine

22
Q

List the potential causes of post-hepatic jaundice

A
  • Gall stones (cholelisthesis)
  • PSC
  • Cholangiocarcinoma
  • Head of pancreas mass
  • Acute/Chronic Pancreatitis
23
Q

What does the colour of stool and urine tell you about the cause of jaundice ?

A
  1. Normal urine + normal stools = pre-hepatic cause
  2. Dark urine + normal stools = hepatic cause
  3. Dark urine + pale stools = post-hepatic cause (obstructive)

If bile and pancreatic lipase’s are unable to reach the bowel because of a blockage (e.g. in obstructive post-hepatic pathology), fat is not able to be absorbed, resulting in stools appearing pale, bulky and more difficult to flush.

24
Q

What are the LFT results suggestive of a pre-hepatic cause of jaundice ?

A
25
Q

What is the most common cause of a isolated raised jaundice ?

A

Gilberts syndrome

26
Q

What is the relevence of AST/ALT ratios?

A

AST > ALT is seen in cirrhosis and acute alcoholic hepatitis (basically think alcohol if AST/ALT ratio > 2)

27
Q

Describe the LFT results you would expect for intrahepatic and then post-hepatic jaundice

A

Intrahepatic jaundice:

  • Expect a markedly increased ALT comapred to ALP (which is also raised), also PT/INR increased

Post-hepatic:

  • Expect a markedly increased ALP compared to ALT (which is also raised). If so check GGT because if also increased then very likely post-hepatic. If not then consider other causes of rasied ALP
28
Q

What investigations should be done for a patient presenting with jaundice

A

Any patient presenting with jaundice should have the following bloods taken:

  • LFT’s
  • Coagulation studies (PT can be used as a marker of liver synthesis function)
  • FBC (anaemia, raised MCV, and thrombocytopenia all seen in liver disease) and U&Es
  • Specialist blood tests, as summarised below as part of a liver screen
29
Q

What does a liver screen include ?

A
  • LFTs
  • Coagulation screen
  • Hepatitis serology (A/B/C)
  • Epstein-Barr Virus (EBV)
  • Cytomegalovirus (CMV)
  • Anti-mitochondrial antibody (AMA)
  • Anti-smooth muscle antibody (ASMA)
  • Anti-liver/kidney microsomal antibodies (Anti-LKM)
  • Anti-nuclear antibody (ANA)
  • p-ANCA
  • Immunoglobulins – IgM/IgG
  • Alpha-1 Antitrypsin – Alpha-1 Antitrypsin deficiency
  • Serum Copper – Wilson’s disease
  • Ceruloplasmin – Wilson’s disease
  • Ferritin – Haemochromatosis
  • Tissue transglutaminase antibody (TTG) - for coeilacs

Y4 Gastrointestinal (28 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions