Introduction and Chemical Pathology Lab

Question 1

what tests should the doctor order for the following symptoms?

Answer 1

Question 2

what does a fever suggest?

Answer 2

infection is the likely cause

• There are some autoimmune conditions that cause fever because fever is NOT caused by the organism but is instead caused by the immune response

Question 3

what is the ESR? Erythrocyte Sedimentation Rate

what happens to ESR in infection?

Answer 3

the rate at which red blood cells settle out of suspension in blood plasma, measured under standardized conditions

• the ESR increases in infection

Question 4

what tests are done by chemical pathologists?

Answer 4

LFTs - liver function tests

U&E - urea and creatinine

Blood glucose

Question 5

what do the different colours of tubes for collecting blood mean?

Answer 5

different colored tops have different anticoagulants in them

• red top = no anticoagulant
• yellow top = have a gel to speed up the clot
• purple top = have potassium EDTA
• grey top = has fluoride oxalate (poison)

Question 6

what does potassium EDTA do?

Answer 6

keeps the cells alive if you want to test the cells you must keep them alive

Question 7

what does fluoride oxalate do?

Answer 7

is a type of poison that kills the red blood cells

• needed if we want to measure blood glucose
• if red cells are alive they will consume glucose so not accurate

Question 8

what is HbA1c mean?

Answer 8

• If glucose sticks to the hemoglobin it becomes a bit heavier and its movement slows down
• so when you do electrophoresis
• patients with poorly controlled diabetes there is more HbA1c
• as RBCs survive 3 months it shows the last 3 months of glucose control

Question 9

what What’s the difference between serum and plasma?

Answer 9

• if there is no anticoagulant in the tube the blood tends to clot
• when it clots all the clotting factors are used up so when we remove the clot we are just left with serum
• the serum has no clotting factors

Question 10

why is serum useful and how to extract it?

Answer 10

• the serum is useful for measuring electrolytes
• the blood is centrifuged
• the clotting gel induces clotting
• the gel is arranged so it is denser than the serum, so the serum is preserved

Question 11

what might happen if one carries out a poor blood collection?

(potassium)

Answer 11

• if you pull too hard on the syringe the blood collection might be poor
• the cells will become lysed
• if the RBCs haemolyse there will be extra potassium in the plasma
• you can notice this extra potassium as it will make the sample will appear pink
• the machine will dispose of the sample as this level of potassium is incompatible with life

Question 12

what substances inhibit clotting factors?

Answer 12

EDTA and heparin

Question 13

why is citrate used (blue top)

Answer 13

• citrate is another anticoagulant
• it is useful because it is reversible
• it is used to measure clotting factors
• citrate binds to calcium and prevents it from clotting
• calcium is needed to start the clotting process
• we are then able to measure the time of clotting process

Question 14

why must we use fluoride oxalate when measuring glucose?

Answer 14

• fluoride oxalate kills the red cells which prevent them from taking up the glucose
• red cells take up glucose so the longer it is left out the lower the glucose is read

Question 15

when do we need to contact a chemical pathologist?

Answer 15

• when the sample needs to be looked at rapidly out of hours
• When you want to measure labile hormones such as insulin
• when you need cerebral spinal fluid glucose and protein to be measured urgently

Question 16

analyse the following results : insert the pic looking at the sodium and potassium

Answer 16

• sodium is low
• potassium is high

with this combination maybe adrenal failure (beware of haemolysis as this might give a high potassium reading)

• the urea is high and the creatinine is normal

urea shows hydration , creatinine shows how well kidneys are working

Question 17

what does creatintine show?

Answer 17

• creatinine is excreted by the kidneys
• creatinine is produced by the muscle
• in adults, muscle mass remains roughly the same so the amount of creatinine one is making remains the same
• the level of creatinine in the blood shows the functioning of the kidneys

Question 18

what does urea show?

Answer 18

• Urea is a marker of how DEHYDRATED you are
• When you are dehydrated, the kidneys start reabsorbing more water and accidentally absorbs some urea by ADH
• so dehydration causes high Urea

Question 19

what happens to urea and creatinine in kidney disease`?

what happens to urea and creatinine in dehydration?

Answer 19

urea and creatinine concentrations will rise

urea will rise, creatinine will remain the same

Question 20

where are liver enzymes present?

Answer 20

• Present in the liver (within hepatocytes)
• A tiny amount normally leaks in to the blood

Question 21

what happens to the liver enzymes in liver disease?

Answer 21

more of these enzymes leak into the blood

Question 22

what are popular enzymes measured in liver function tests?

Answer 22

Alanine Aminotransferase (ALT)

Aspartate Aminotransferase/Transaminase (AST)

Alkaline Phosphatase (ALP)

Question 23

what is TBil?

what results in high TBil

Answer 23

Total Bilirubin - (excreted in the faeces through the bile)

• If there is something wrong with the liver or the biliary tree then bile will leak into the blood so you get high bilirubin

Question 24

what is liver albumin for?

Answer 24

if the liver fails albumin falls

Question 25

what are osteoblasts for?

Answer 25

Osteoblasts also use Alkaline Phosphatase when they cause bone growth

• alkaline phosphatase, therefore, is both a bone enzyme and a liver enzyme
• so after a fracture the ALP might rise a bit as the ones are growing and the osteoblasts secrete more ALP

Question 26

interpret billys liver enzyme results?

Answer 26

billys bilirubin is very high

• above 30 means the jaundice is very clear

Question 27

where are cardiac enzymes found?

Answer 27

there are enzymes in the cardiac tissue that should not normally be found in the blood

Question 28

when are cardiac enzymes released?

Answer 28

• when there is damage to the heart muscle and some tissue dies it will release some more enzyme

Question 29

what is the list of cardiac enzymes?

Answer 29

Troponins Creatine Kinase (CK)

Aspartate Aminotransferase (AST)

Lactate Dehydrogenase (LDH)

Question 30

what do we do when we see some of these cardiac enzymes in the blood?

Answer 30

• take an ECG
• then check the troponins they might be raised for a heart attack

if the ECG is abnormal and the troponin is raised it is a heart attack

Question 32

overall what do billys blood test results show?

Answer 32

low Na and high K suggests renal failure

but high urea and normal creatinine shows dehydration but normal kidneys

low albumin suggests the liver isn’t working

high liver enzymes shows liver damage