Introduction and chemical pathology lab Flashcards
What are the different tubes for collecting blood and what do they contain?
Red top= no anticoagulant Yellow top= have gel to speed up clot Purple top= have potassium EDTA Grey top= have fluoride oxalate (poison) Blue top= citrate (anticoagulant)
What does the potassium EDTA do?
It keeps the cells alive- what you want if you want to do anything with the cells (red, white and platelets)
What does fluoride oxalate do and when is it used?
It is a type of poison that kills the red blood cells, it is used if you want to measure blood glucose- if cells are alive they will consume glucose
What is HbA1c?
Glycated haemoglobin
What would you expect to find in terms of HbA1c when performing electrophoresis on the blood of someone with poorly controlled diabetes?
More HbA1c which will be found at bottom
For what period of time does the electrophoresis show you how good blood glucose control has been?
3 months because that’s how long red blood cells survive
What is the difference between serum and plasma?
Serum contains no clotting factors
What is serum useful for measuring?
Electrolytes
How would you get just the serum from the blood?
Add it to a yellow top tube, the gel will speed up coagulation and use up all the clotting factors, the serum and cells are then separated by centrifuge because the cells are more dense than the gel and the gel is more dense than the serum so it separates the two, you can then use a tube to just suck out the serum
What is a problem with poor blood collection?
Cells are full of potassium
If you do a poor collection and pull hard on syringe you will lyse cells and there will be extra potassium in the plasma which will affect results- you can notice it because it looks pink
Why is citrate useful as an anticoagulant?
It is reversible
What is citrate used to measure?
Clotting factors
How does citrate act as an anticoagulant?
It binds to calcium and prevents clotting
How do you measure clotting factors once you have a sample in the citrate bottle?
You add just the right amount of calcium to start the clotting process then measure the clotting time- PT and APTT- there is a fixed amount of calcium so you need to put the right amount of blood into the tube
When do you need to contact a chemical pathologist?
When you want a 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
Meningitis- if there is bacteria they will consume glucose
If someones results contained low sodium and high potassium what would you consider?
Adrenal failure
What is the link between urea and creatinine?
The kidneys excrete both
Where is creatinine produced?
In the muscle and produced constantly
Why does the amount of creatinine that you produce stay the same through adult life?
Your muscle mass normally roughly stays the same
As the creatinine production rate is fixed, what does the level of creatinine in the blood show you?
How well your kidneys are functioning- marker of GFR
How much do urea levels vary?
A little bit depending on your diet- it comes from protein
What is urea a marker of?
How dehydrated you are
What happens in the kidney when you are dehydrated in terms of urea?
You start reabsorbing more water and accidentally absorb some urea
If someone had high urea and normal creatine, what would you suspect?
Dehydrated with normal kidney function
What will happen to urea and creatine levels in renal disease?
Both will rise
What will your potassium, sodium, urea and creatine levels be like in addison’s disease?
High potassium
Low sodium
High urea
Normal creatine
Where are liver enzyme found?
In the liver within hepatocytes
Tiny amount leaks into blood
In terms of liver enzymes, what happens during liver disease?
More leak into the blood
What common enzymes are measured in liver function tests?
Alanine Aminotransferase (ALT) Aspartate Aminotransferase/Transaminase (AST) Alkaline phosphate (ALP)
What is TBil?
Total bilirubin (excreted in the faeces through bile) (increases with liver failure or biliary tree problems)
What happens when the liver fails in terms of albumin?
Liver albumin will fall
What do you need to measure if a patient has jaundice?
Liver: - Albumin -Bilirubin -Alkaline phosphatase -ALT AST GGT
What is the first thing you do when you have a patient presenting with heart attack type symptoms?
ECG to see if they’re having an acute heart attack
If you suspect a heart attack, what enzyme do you check?
Troponin
What other cardiac enzymes are there which will be elevated when there is damage to the heart muscle?
Troponin
Creatinine kinase
Aspartate aminotransferase
Lactate dehydrogenase
