Introduction and Chemical Pathology Lab

Question 1

What is ESR and how does it change in infection?

Answer 1

Erythrocyte Sedimentation Rate – the rate at which red blood cells settle out of suspension in blood plasma, measured under standard conditions

ESR increases in infection

Question 2

Fever is normally a sign of infection. How is it possible for some autoimmune conditions to cause fever?

Answer 2

Fever is caused by the immune system rather than the organism Hence it can occur in autoimmune disease in the absence of an organism

Question 3

What are the four tube colours for blood collection and what do the colours mean?

Answer 3

Red – no anticoagulant
Yellow – gel – makes the coagulation occur faster Purple – potassium EDTA
Grey – fluoride oxalate (poison)

Question 4

What are the purple cap bottles used for?

Answer 4

Potassium EDTA keeps the cells alive

It is used when measuring cell counts or anything in general to do with the cells

Question 5

What are the grey cap bottles used for?

Answer 5

Fluoride oxalate kills the red blood cells – this is used for measuring blood glucose because live red blood cells will consume the glucose

Question 6

Which bottle is used for measuring HbA1c?

Answer 6

Purple Top – potassium EDTA

Question 7

What is serum and what is it useful for measuring?

Answer 7

When blood clots and you remove the clot you are left with serum

Serum contains electrolytes but NO clotting factors

Question 8

How is gel designed so that it separates serum from the rest of the blood?

Answer 8

It is more dense than serum but less dense than cells so it separates the serum from the cells

Question 9

What can skew the electrolyte measurements of the serum?

Answer 9

Haemolysis – red cells contain a lot of potassium so haemolysis caused by poor collection or the sample being left out too long will result in an increased serum potassium concentration

Question 10

What does the blue top mean?

Answer 10

Contains citrate
It is reversible and used to measure clotting factors
Citrate binds to calcium and prevents clotting
When you get a sample of blood in a citrate bottle, you add just the right amount of calcium to trigger the clotting cascade

Question 11

What is the blue top used to measure?

Answer 11

Prothrombin time (PT) - measures integrity of extrinsic system

Active partial thromboplastin time (APTT) - measures integrity of intrinsic system

Question 12

What is creatinine a marker of?

Answer 12

Renal function (GFR) – it is produced by the body at a constant rate and it is excreted at a constant rate provided that the kidneys are functioning normally with little absorbed or secreted

Question 13

What is urea a marker of?

Answer 13

Dehydration

It is also excreted by the kidneys

Question 14

How do urea and creatinine change in renal disease?

Answer 14

They increase, urea rises first

Question 15

What are the three main liver enzymes?

Answer 15

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

Question 16

How does albumin change in liver disease?

Answer 16

Albumin levels fall in liver disease

Question 17

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

Answer 17

Osteoblasts

Question 18

Other than liver disease, when else might ALP be high?

Answer 18

After a fracture – osteoblasts use ALP to build more bone

Question 19

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

Answer 19

ECG

Question 20

What is measured to confirm a heart attack?

Answer 20

Measure troponin levels

Question 21

List the main cardiac enzymes.

Answer 21

Troponins  
Creatine Kinase (CK) Aspartate aminotransferase (AST) 
Lactate dehydrogenase (LDH)

Question 22

What else could cause heart attack type symptoms?

Answer 22

A bleeding peptic ulcer

Question 23

What is HbA1c?

Answer 23

HBA1c is glycated heamoglobin;
if glucose sticks to Hb –> Hb is heavier –> moves less on electrophoresis;
poorly-controlled diabetes = more HBA1c + stronger band