Laboratory Diagnostic Methods Flashcards Preview

Year 2 - MCD - Diagnostics > Laboratory Diagnostic Methods > Flashcards

Flashcards in Laboratory Diagnostic Methods Deck (35)
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1
Q

Why is it important to only do the necessary tests?

A
  • many tests are expensive and this is a cost to the NHS
2
Q

What are rashes a sign of?

A

Allergies

Infection (specific ones e.g. shingles)

3
Q

FBC

A

Full Blood Count

4
Q

ESR

A

Erythrocyte Sedimentation Rate
(if it is higher than usual it is a sign of infection, usually 1mm per hour, it is how much the erythrocytes fall in a timespan of 1h)

5
Q

CRP

A

C reactive protein (marker or inflammation)

6
Q

LFTs

A

Liver Function tests

7
Q

U&E

A

Urea and Electrolytes

8
Q

What is important when filling out a blood sample form?

A
  • tick the tests you want
  • double check the patients name (ask them what their name is, check their bracelet)
  • make sure you use the correct tube!
  • let the lab know if it is urgent
9
Q

Which tube is used for U&E?

A

Serum in yellow/red top

10
Q

What anticoagulants are inside the different blood tubes?

A

Red top - have none
Yellow top - have gel to speed up clot
Purple top - have potassium EDTA (keeps cells alive, measure Hb, RBCs, FBC but not for electrolytes due to K)
Grey top - have fluoride oxalate (poison) -> to top red cells from glycolysis and measure glucose levels

11
Q

Which tube is used for Glucose?

A

Glucose: plasma in grey top

12
Q

Which tube is used for HbA1c?

A

Plasma in purple top

13
Q

Which tube is used for TFT?

A

Serum in yellow / red top

14
Q

Which test tube is used for LFT?

A

Yellow / Red top

15
Q

What is the difference between Serum and Plasma?

A

Plasma has clotting factors. Plasma does not have clotting factors.

16
Q

Why is it important to have a blood sample checking for insulin done fast?

A
  • Insulin is very labile

- you cannot wait an hour

17
Q

HbA1c

A
  • long term indicator of glucose levels
18
Q

How do things seperate in the yellow tube?

A
  • Hb is heavy and goes to the bottom
  • gel intermediate
  • serum is light and stays in the top
19
Q

When would you use no anticoagulant? What happens?

A
  • U&E : serum in yellow/red top
  • Blood clots, using up all clotting factors
  • Clot can be removed, leaving serum
20
Q

What happens in a tube with anticoagulant?

A
  • EDTA or heparin
  • Clotting factors unused
  • Blood can be separated into red cells and plasma
  • plasma has clotting factors (serum does not)
21
Q

What is in a tube with a blue top?

A

citrate (for measuring clotting factors)

22
Q

Measuring glucose

A
  • Red cells consume glucose (anaerobic glycolysis), so the longer this is left out, the lower the glucose may read
  • Fluoride Oxalate (poison) prevents the red cells from using glucose

KNOW THIS

23
Q

What is measured in liver function testing?

A
  • albumine
  • ALP
  • ALT (alanine transferase)
  • TBil (Bilirubin)
24
Q

What is important when sending a CSF sample to the lab?

A
  • make sure that they have time before you take the sample
  • it should be analysed right away
  • e.g. if you are suspecting meningitis you want to know the amount of glucose and protein in CSF (low glucose would indicate bugs in the CSF)
25
Q

CSF sample - what are the results in bacterial meningitis?

A
  • high protein

- low glucose

26
Q

When do you need to contact a chemical pathologist?

A
  • 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
27
Q

What is a potential cause of high potassium by staff error?

A

Haemolysis: if you aspirate very hard the blood cells will aspirate and the potassium might go up because blood was not taken well. Then the lab would generally say: potassium: heamolysed
You have to have a needle thick enough to avoid hameolysis.

28
Q

What is creatinine a marker of?

A

GFR

29
Q

What does a normal creatinine and a high urea suggest?

A

dehydration

30
Q

What to high urea and high creatinine suggest?

A
  • kidneys not working properly
  • renal failure
  • kidney damage also causes an increase in creatinine
31
Q

Liver enzymes

A
  • Are present in the liver
  • A tiny amount normally leaks into the blood
  • In liver disease, more of these enzymes leak into the blood
  • With experience you can tell what liver disease a patient has from the pattern of the leak…
32
Q

What test would you order for a better look at the liver values?

A
  • Liver
  • gamma GT
  • AST
33
Q

What tests show the function of the liver?

A
  • In addition to “Liver”, one would need to measure AST and GGT in a patient with jaundice
  • “Liver” includes
    Albumin: synthesised in the liver
    Bilirubin
    Alkaline Phosphatase
    ALT (alanine amino-transferase)
  • > if the liver fails you make less albumin
  • > Hb is broken down to Bilirubin which is dark yellow or brown; liver problem: the faeces are pale and urin is brown
  • > ALP shows that there is something wrong with bile
  • > ALT is high in hepatitis
34
Q

Cardiac enzymes

A

Are present in the heart muscle
During a heart attack, heart muscle is damaged

These enzymes leak into the blood in large amounts
Thus we can tell you if someone has really had a heart attack

Diaebtic patients have neuropathy, they might not know that they have damage to the heart because they don’t feel the pain.

35
Q

What are the specific cardiac enzymes that are tested for?

A

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

=> by the patterns you can tell when the MI occurred