1: Intro and Chemical Pathology

Question 1

What is a Liver Function test? (LFT)

List the markers

Answer 1

Testing for markers that are in the bloodstream. Amount of markers INCREASE with liver damage.

AST, ALT, GGT
Albumin = produced by liver, marker of liver health

Any sepsis can make LFT abnormal

Question 2

List the urea & electrolyte markers that can be tested

Answer 2

Urea
Creatinine
Na+
K+

Question 3

What is ESR?

Answer 3

Erythrocyte sedimentation rate

It is a marker of chronic inflammation

Question 4

What types of stool culture are there?

Answer 4

Microscopy - can tell you if its parasitic or bacterial
Culture (takes longer to develop)
Sensitivity - tells you which antibiotic to use

Question 5

What are the different blood test tubes?

Answer 5

RED top = NO anticoag
YELLOW top = gel to speed up clot
PURPLE top = Potassium EDTA
GREY top = Fluoride oxalate (poison)

Question 6

What is the purpose of Potassium EDTA in purple tops?

Answer 6

Potassium EDTA keeps the cells alive

So if you want to do anything with cells you need purple top

Question 7

What is the purpose of fluoride oxalate?

Answer 7

KILLS red blood cells
Used if you want to measure blood glucose
(RBCs consume glucose so will give inaccurate reading)

Question 8

What colour test tube do you use for each test?

Answer 8

U&E = serum in yellow/red top
Glucose = plasma in grey top
HbA1c = plasma in purple top
TFT = serum in yellow/red top
LFT = yellow/red top

Question 9

What is HbA1c?

Answer 9

Glycated Hb

Form of Hb that is covalently bound to glucose

Question 10

What is the difference between serum and plasma?

Answer 10

Serum has NO coag factors
Useful for measuring electrolytes
Red top has no anticoagulant so blood will clot and use up all the coag factors - then you are left with just serum

Question 11

Why would you want to use anti-coagulant in test tubes?

Name the anti-coags used

Answer 11

If you want to separate blood into RBCs + plasma
Blood wont clot and will remain as a liquid. Clotting factors wont be used up

Use EDTA or heparin

Question 12

If red cells haemolyse during blood collection, what would you see after centrifuging the sample?

Answer 12

PINK plasma
Because cells are full of potassium, and there would be extra potassium in the plasma due to haemolysis

High potassium level = fucked

Question 13

What is the BLUE top container?

Answer 13

Contains citrate, an anticoagulant (binds to calcium)
Useful as it is reversible
It is used to measure clotting factors

When sample is given in citrate bottle, you add a shot of calcium to START the clotting process (i.e. reverse the anticoag effect)

Then you can measure PT/APTT

Question 14

When do you contact a chemical pathologist?

Answer 14

• When you want the sample to be rapidly centrifuged out of hours
• When you want to measure labile hormones (insulin)
• When you urgently need CSF glucose and protein to be measured (e.g. in meningitis, bacteria would consume CSF glucose)

Question 15

What is creatinine? What does it indicate?

Answer 15

Creatinine = marker of GFR (kidney function)
Normal creatinine = normal kidney function

Its produced CONSTANTLY in muscle
Muscle mass is roughly the same throughout adulthood so rate of creatinine production is FIXED.

Creatinine is NEVER reabsorbed

Question 16

What is urea? What does it indicate?

Answer 16

Urea = marker of dehydration

When dehydrated, kidneys reabsorb some urea along with water

Urea levels = High if dehydrated, but GFR stays the same til the end

Question 17

What are the typical U&E results for Addison’s disease?

Answer 17

Low Na+
High K+
High urea
Normal creatinine

Question 18

What are common markers tested in LFT?

Answer 18

ALT = Alanine Aminotransferase
AST = Aspartate Aminotransferase
ALP = Alkaline Phosphatase
These can leak into blood if liver is damaged
HIGH liver enzyme levels = LIVER DAMAGE

ALP is also used by osteoblasts in bone growth. You can measure liver/bone specific ALP
After FRACTURE -> ALP will rise (osteoblasts secrete ALP)

HIGH Total Bilirubin = Liver/biliary tree damage
If something’s wrong with liver/biliary tree, bile will LEAK into blood -> HIGH total bilirubin

Albumin - synthesised in the liver
LOW albumin = LIVER DAMAGE

Question 19

In a patient with jaundice what other liver markers would you need to measure?

Answer 19

AST and GGT

Question 20

List the cardiac enzymes

Answer 20

Troponins
Creatine Kinase
AST
Lactate Dehydrogenase (LDH)

Normally found in cardiac tissue, should NOT be present in blood

Question 21

If patient presents with chest pain + tightness, what tests should you do next?

Answer 21

1. ECG to see if they’re having an acute heart attack
2. If you suspect heart attack, check cardiac enzymes
   RAISED TROPONIN = HEART ATTACK

Heart attack symptoms also caused by PEPTIC ULCERS
Careful not to give thrombolytics to someone with bleeding ulcers