Diagnostics

Question 1

What is ESR

Answer 1

Erythrocyte Sedimentation Rate

Rate at which red blood cells settle out of suspension in blood plasma, measured under standard conditions

Question 2

What is CRP

Answer 2

CRP = C-reactive protein, made by liver during infection

Question 3

What do the colours of blood tubes mean

Answer 3

Red top - no anticoagulant
Yellow top - gel to speed up clot
Purple top - potassium EDTA
Grey top - have fluoride oxalate (poison)

Question 4

What is the function of EDTA In purple top tubes

Answer 4

Keep the cells alive. Cannot be used for U+E due to potassium content
It is used when measuring cell counts or anything in general to do with the cells

Question 5

What is the function of fluoride oxalate in grey top tubes

Answer 5

Kills red blood cells

glycolysis in red cells - used for glucose measurement as live cells would consume the glucose

Question 6

What tubes are used for the different tests

Answer 6

U+E : serum in yellow/red top
Glucose: plasma in grey top
HBA1c: plasma in purple top
TFT: serum in yellow/red top
 Liver function tests: in yellow/red top

Question 7

Which tests use no antigoagulant and why

Answer 7

U+E : serum in yellow/red top
Blood clots, using up all clotting factors
Clot can be removed, leaving serum

Question 8

Which tests use anticoagulant and why

Answer 8

EDTA or heparin
Clotting factors unused
Blood can be separated into red cells and plasma

Question 9

What are the layers of a blood sample in a tube with anticoagulant

Answer 9

1. Erythrocytes
2. Gel barrier
3. Density gradient fluid
4. Lymphocyte and monocyte band
5. Plasma

Question 10

When should a chemical pathologist be contacted

Answer 10

When you want the sample to be rapidly centrifuged out of hours
When you want to measure labile hormones such as insulin
When you urgently need CSF glucose and protein to be measured

Question 11

How is creatinine used as a marker of renal function

Answer 11

marker of glomerular filtration rate.
If it is normal, then the GFR is normal
Very little is absorbed or secreted by the tubules

Question 12

In what situation would urea levels rise

Answer 12

patient is dehydrated but GFR stays the same to the end

Question 13

Describe liver enzymes

Answer 13

Are present in the liver
A tiny amount normally leaks into the blood
In liver disease, more of these enzymes leak into the blood

Question 14

What needs to be measured in suspected jaundice

Answer 14

Liver enzymes
AST (alanine amino-transferase)
GGT 
Albumin (synthesised in liver)
Bilirubin 
Alkaline phosphatase

Question 15

Describe cardiac enzymes for diagnosis

Answer 15

Are present in the heart muscle
During a heart attack, heart muscle is damaged
These enzymes leak into the blood in large amounts
Measure troponin levels

Question 16

Give examples of cardiac enzymes

Answer 16

Troponins
Creatine kinase (CK)
Aspartate amino transferase (AST)
Lactate Dehydrogenase (LDH)

Question 17

What happens to ESR in infection

Answer 17

ESR increases

Lots of proteins and inflammatory cells -> red cells settle faster

Question 18

What can creatinine and urea changes be used as a marker for

Answer 18

Increases in both mark renal disease

Question 19

What are the 3 main liver enzymes

Answer 19

Alanine aminotransferase (ALT) 
Aspartate aminotransferase (AST) 
Alkaline phosphatase (ALP)

Question 20

What other cells, other than hepatocytes, contain alkaline phosphatase?

Answer 20

Osteoblasts

Question 21

When may ALP be high

Answer 21

After a fracture – osteoblasts use ALP to build more bone

Question 22

What is the first thing you do if a patient presents with heart attack type symptoms?

Answer 22

ECG

Question 23

What else can cause heart attack type symptoms

Answer 23

A bleeding peptic ulcer

Question 24

What could allow CSF glucose be indicative of

Answer 24

meningitis (due to bacteria consuming the glucose)

Question 25

What is found in blue top tubes and what is its function

Answer 25

Citrate (anticoagulant)
Add calcium to cause sample to clot, citrate removes calcium -> can time how long clotting takes – measures clotting factor production by liver; must fill tube to top