chemical pathology

Question 1

in blood tubes, what does the:

1. red top
2. yellow top
3. purple top
4. grey top contain

Answer 1

1. red = no anticoagulant
2. yellow = gel to speed up clotting
3. purple = potassium EDTA (stops blood clotting and preserves cells)
4. grey = fluroide oxalate (poison to RBCs so used when want to measure blood glucose)

Question 2

if you wanted to measure glucose, which bottle would you use?

Answer 2

plasma in grey top

Question 3

if you wanted to measure HBA1c, which bottle would you use?

Answer 3

• plasma in purple top

- is a Hb with glucose attached to it

Question 4

what top would you use to measure TFT and LFT?

Answer 4

TFT - serum in yellow/red top

LFT - yellow/red top

Question 5

what is the difference between serum and plasma?

Answer 5

• serum: no clotting factors

- plasma: serum + clotting factors

Question 6

what would confound a potassium measurement? what could cause this?

Answer 6

• cells are full of potassium so haemolysis will confound K results
• poor blood collection can result in this

Question 7

when would you use an anticoagulant in blood collection? which one would you use?

Answer 7

• using an anticoagulant, the clotting factors remain unused
• blood can be separated into red cells and plasma
• citrate is used that is reversible
• used to measure PT, APTT

Question 8

are liver enzymes in the blood?

Answer 8

• tiny number of liver enzymes leak into blood

- but in liver disease, lots of these enzymes leak into blood

Question 9

what are the enzymes usually measured in liver tests?

Answer 9

• ALT (alanine aminotransferase)
• AST (aspartate aminotransferase)
• ALP (alkaline phosphatase)
• albumin
• bilirubin

Question 10

what is another occasion that will cause a rise in ALP?

Answer 10

post fracture

ALP will rise as osteoblasts secrete ALPs as they make new bone

Question 11

what should you do when you suspect an MI?

Answer 11

• ECG
• troponins
• CK
• AST
• LDH