LFTs

Question 1

What is serum albumin used to determine?

Answer 1

Marker of liver synthetic function. Helps gauge severity of chronic liver disease: falling = bad prognosis. Levels may be initially normal in acute liver disease.

Question 2

What is prothrombin time and how does it indicate liver function?

Answer 2

Prothrombin Time (PT): marker of synthetic function; both acute and chronic liver disease.

Question 3

How and why should Vit K be considered when investigating PT time?

Answer 3

Exclude Vit K deficiency as cause of prolonged PT by giving IV Vit K bolus (10mg).

Vit K deficiency may occur in biliary obstruction: low intestinal {bile salts] results in poor Vit K absorption.

Question 4

What is AST?

Answer 4

AST: mitochondrial enzyme (80% in cytoplasm); also present in heart, muscle, kidney and brain.

High levels = hepatic necrosis, MI, muscle injury and CCF.

Question 5

What is ALT?

Answer 5

ALT: cytosol enzyme more specific for liver. Rises only in liver disease.

Question 6

What is ALP and what does it indicate if raised?

Answer 6

ALP: present in hepatic canalicular and sinusoidal membranes (but also in bone, intestine and placenta).
If GGT also abnormal, ALP presumed to be of liver origin

Raised in both intra- and extra-hepatic cholestatic disease of any cause, due to increased sythesis.

• Cholestatic jaundice: levels up to 4 - 6 x normal
• Hepatic metastases
• Cirrhosis

Question 7

What is GGT?

Answer 7

GGT: microsomal enzyme present in many tissues. Activity can be induced by drugs and alcohol.
If ALP = normal, raised GGT can be a guide to alcohol consumption
Raised in fatty liver disease
GGT and ALP rise similarly in cholestatic disease (have similar path to excretion).

Question 8

What pattern does hepatocellular injury demonstrate in relation to LFTs?

Answer 8

AST and ALT elevated.
Prompt evaluation e.g. history from family (alcohol consumption etc.)
Ultrasound for fatty liver, metastases
Viral serology (HAV, HBV, HCV)

Question 9

What LFT pattern is present in alcoholic liver disease?

Answer 9

Alcoholic liver disease: AST/ALT ration 2:1 +. Normal ALP, increased GGT and macrocytosis.

Question 10

Bilirubin range

Answer 10

3 - 17 umol/L

Question 11

ALT range

Answer 11

5 - 35 iu/L

Question 12

AST range

Answer 12

5 - 35 iu/L

Question 13

ALP range

Answer 13

30 - 150 iu/L

Question 14

Albumin range

Answer 14

35 -50 g/L

Question 15

Protein total range

Answer 15

60 - 80 g/L

Question 16

Why does obstructive picture emerge in cirrhosis?

Answer 16

Duct may be partially obstructed by fibrosis.