Liver function tests

Question 1

Enzymes associated with hepatocellular injury

Answer 1

ALT- alanine transaminase

AST- asparate transaminase

Question 2

Enzymes associated with obstruction

Answer 2

ALP- alkaline phospotase

GGT- gamma glutynl transferase

Question 3

Functional tests of the liver

Answer 3

Albumin
Coagulation factors, prothrombin ratios
Glucose

Question 4

Describe the process of bilirubin metabolism

Answer 4

1. bilirubin produced as byproduct of heam metabolism
2. bilirubin joins with albumin to be transported to the liver (called unconjugated bilirubin)
3. In the liver albumin is released and glucuronide joins to the bilirubin conjugating it.
4. the conjugated bilirubin then travels via the bile and bile duct to the GI tract
5. IN the large intestine bacteria convert the conjugated bilirubin to urobilinogen where it is excreted out mostly in the fees
6. Some urobilinogen enters the enterohepatic circulation and is then excreted in the urine

Question 5

Causes of jaundice

Answer 5

Indirect
Increased haemolysis, leads to increased uncontested bilirubin and increased load on the liver. Not too bad if no obstruction, only increased urobilinogen in stools and urine.
If there is a biliary obstruction the levels of urobilinogen go down (pale stools) and serum levels of conjugated biliruni go up
Gilbert’s syndrome; where there is a reduced activity of an enzyme used in conjugation of bilirubin
DIRECT (inside liver)
Cholestasis- pregnancy, drugs, thyroid disease
Obstruction inside the liver- hepatitis, cirrhosis, mass
DIRECT (outside liver)
Cholecodolithisis
Cancer
Pancreatitis

Question 6

ALP

Answer 6

Transfers phosphate groups.

Can also go up in times of excessive bone growth, pregnancy, and some cancers

Question 7

GGT

Answer 7

Pathologies in heart, lung and pancreas may also raise GGT
Elevated in obstructive pathologies
Inducable- drugs, alcohol (mild increase in normal alcohol use). Sensitivity not great only goes up in 2/3rds of heavy drinkers)

Question 8

ALT

Answer 8

Involved in amino acid synthesis and gluconeogenisis
Specific test to the liver. You need significant damage to other organs before levels of ALT go up. Long half life
Hepatitis most common cause of elevation

Question 9

AST

Answer 9

Gluconeongenesis
Short half life
Hepatitis most common cause of elevation

Question 10

Albumin

Answer 10

Decreased synthesis or increased loss (nephronopathy)

Falls with non-specific illness, oedema

Question 11

Globulins

Answer 11

Reflect chronic inflammation

Question 12

INR prothrombin ratio

Answer 12

Synthesis of clotting factor, vitamin K

Question 13

Glucose

Answer 13

Liver maintains fasting blood glucose

Question 14

Signs of scarring and declining liver function

Answer 14

Persistant GGT, ALP elevation
Increased AST/ALT
Increased immunoglobulins
Decreased albumin
Increased bilirubin
Increased INR
Decreased blood glucose
Increased NH3 (Liver converts NH3 to urea increased NH3 leads to encephalopathy)

Question 15

Explain a blood report with elevated GGT and ALP but normal bilirubin

Answer 15

GGT and ALP my go up if there is an obstruction on one part of the liver but the rest can still effectively move bilirubin to the GI tract so bilirubin levels ok (would not occur if the obstruction was in end ducts only in earlier ducts).

Question 16

CEA. What will raise level and what level is indicative of serious disease?

Answer 16

Carcinoembryonic Antigen
Raised in smokers, hepatitis, cirrhosis, ulcerative colitis, renal failure, and cancer.
Level over 20- probably cancer. Usually bowel cancer.

Question 17

The fucked liver- 35 yo alcoholic woman. Low albumin, raised enzymes (all, specifically transaminases), high bilirubin and INR. Explain why all enzymes raised

Answer 17

Transaminases indicate actute inflamation.

GGT inducible from alcohol. Also raised GGT and ALP may occur due to chronic inflammation, scarring, obstruction,

Question 18

Causes of liver function test abnormalities and percentages

Answer 18

Fatty liver (45%)
Viral hepatitis (27%)
Alcohol (8%)
Haemochromotosis (3%)
Other- drugs, cancer, autoimmune etc.