LFTs

Question 1

why are LFTs ordered?

Answer 1

1. to confirm clinical suspicion of potential liver injury or disease
2. to distinguish between hepatocellular injury (hepatic jandice) and cholestasis (post-hepatic or obstructive jaundice)

Question 2

what blood tests are used to assess liver function?

Answer 2

alanine transaminase (ALT)
aspartate aminotransferase (AST)
alkaline phosphatase (ALP)
gamma-glutamyltransferase (GGT) 
bilirubin 
albumin 
prothrombin time (PT)

Question 3

what is used to distinguish between hepatocellular damage and cholestasis?

Answer 3

ALT
AST
ALP
GGT

Question 4

what is used to assess the liver’s synthetic function?

Answer 4

bilirubin
albumin
PT

Question 5

ALT

Answer 5

3-40 iu/l

Question 6

AST

Answer 6

3-30 iu/l

Question 7

ALP

Answer 7

30-100 umol/l

Question 8

GGT

Answer 8

8-60 u/l

Question 9

bilirubin

Answer 9

3-17 umol/l

Question 10

albumin

Answer 10

35-50 g/l

Question 11

PT

Answer 11

10-14 s/1

Question 12

assessing ALT and ALP

Answer 12

If the ALT is raised, decide if this is a more than a 10-fold rise (↑↑) or a less than a 10-fold rise (↑)
If the ALP is raised, decide if this is a more than a 3-fold rise (↑↑) or a less than a 3-fold rise (↑)

Question 13

where is ALT found in high concs?

Answer 13

within hepatocytes and enters the blood following heptocellular injury

Question 14

where is ALP concentrated?

Answer 14

in the liver, bile duct and bone tissues

often raised in liver pathology due to increased synthesis in response to cholestasis

Question 15

A greater than 10-fold increase in ALT and a less than 3-fold increase in ALP

Answer 15

suggests a predominantly hepatocellular injury

Question 16

A less than 10-fold increase in ALT and a more than 3-fold increase in ALP

Answer 16

suggests cholestasis

Question 17

is it possible to have a mixed picture involving hepatocellular injury and cholestasis?

Answer 17

yes

Question 18

raised GGT

Answer 18

suggestive of biliary epithelial damage and bile flow obstruction
can also be raised in response to alcohol and drugs such as phenytoin

Question 19

markedly raised ALP with a raised GGT

Answer 19

highly suggestive of cholestasis

Question 20

A raised ALP in the absence of a raised GGT

Answer 20

should raise your suspicion of non-hepatobiliary pathology

Question 21

causes of isolated rise in ALP

Answer 21

Bony metastases / primary bone tumours (e.g. sarcoma)
Vitamin D deficiency
Recent bone fractures
Renal osteodystrophy

Question 22

isolated rise in bilirubin

Answer 22

suggestive of a pre-hepatic cause of jaundice

Question 23

Causes of isolated jaundice

Answer 23

Gilbert’s syndrome (most common cause)

Haemolysis (check blood film, full blood count, reticulocyte count, haptoglobin and LDH levels to confirm)

Question 24

the livers main synthetic functions

Answer 24

Conjugation and elimination of bilirubin
Synthesis of albumin
Synthesis of clotting factors
Gluconeogenesis

Question 25

Normal urine + normal stools

Answer 25

pre-hepatic cause of jaundice

Question 26

Dark urine + normal stools

Answer 26

hepatic cause of jaundice

Question 27

Dark urine + pale stools

Answer 27

post-hepatic cause (obstructive) of jaundice

Question 28

causes of unconjugated hyperbilirubinaemia

Answer 28

Haemolysis (e.g. haemolytic anaemia) Impaired hepatic uptake (drugs, congestive cardiac failure) Impaired conjugation (Gilbert’s syndrome)

Question 29

Causes of conjugated hyperbilirubinaemia

Answer 29

Hepatocellular injury | Cholestasis

Question 30

fall in albumin levels

Answer 30

Liver disease resulting in a decreased production of albumin (e.g. cirrhosis) Inflammation triggering an acute phase response which temporarily decreases the liver’s production of albumin Excessive loss of albumin due to protein-losing enteropathies or nephrotic syndrome

Question 31

albumin

Answer 31

synthesised in the liver and helps to bind water, cations, fatty acids and bilirubin plays a key role in maintaining the oncotic pressure of blood

Question 32

PT

Answer 32

a measure of the blood’s coagulation tendency, specifically assessing the extrinsic pathway

Question 33

increased PT

Answer 33

can indicate liver disease and dysfunction

Question 34

ALT > AST

Answer 34

chronic liver disease

Question 35

AST > ALT

Answer 35

cirrhosis and acute alcoholic hepatitis

Question 36

acute hepatocellular damage

Answer 36

ALT ^^ ASP normal or ^ GGT normal or ^ bilirubin ^ or ^^

Question 37

chronic hepatocellolar damage

Answer 37

ALT normal or ^ ASP normal or ^ GGT normal or ^ bilirubin normal or ^

Question 38

cholestasis

Answer 38

ALT normal or ^ ASP ^^ GGT ^^ bilirubin ^^

Question 39

common causes of acute hepatocellular injury

Answer 39

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

Question 40

common causes of chronic hepatocellular injury

Answer 40

Alcoholic fatty liver disease Non-alcoholic fatty liver disease Chronic infection (Hepatitis B or C) Primary biliary cirrhosis

Question 41

less common causes of chronic hepatocellular injury

Answer 41

alpha-1 antitrypsin deficiency Wilson’s disease Haemochromatosis

Question 42

liver screen

Answer 42

``` 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 ```