Introduction and Chemical Pathology Lab [Complete] Flashcards
What is lymphadenopathy? What are the usual causes?
Enlargement of the lymph nodes
Viral illnesses
Glandular fever
Give examples of common investigative tests.
Which tests can be performed by the GP?
FBC
ESR (Erythrocyte sedimantary rate) [Indicates inflammation]
CRP (C-reactive protein) [Indicates infection]
LFT (Liver function test) (measure enzymes in liver enzymes in blood, if in blood indicates liver damage)
U&Es: Urea and electrolytes
Blood glucose
Stool culture (Bacteriology)
GP tests:
LFTs
Blood glucose
U&Es
What is ESR and how does it change in infection?
Erythrocyte Sedimentation Rate: The rate at which red blood cells settle out of suspension in blood plasma, measured under standard conditions
High ESR indicates inflammatoin (e.g infection)
What is ESR and how does it change in infection?
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
What does U&Es test for?
Urea
Creatinine
Na
K
What does liver function tests measure? What can be tested in paticualr as an indicator of liver damage?
Alkaline phosphatase(ALP)
Albumin (Alb)
Alanine aminotransferase (ALT)
Total billirubin (TBil)
Alkaline phosphatase indicates liver damage as this enzyme is produced in the liver and shouldnt be in circulation.
Fever is normally a sign of infection. How is it possible for some autoimmune conditions to cause fever?
Fever is caused by the immune system rather than the organism
Hence it can occur in autoimmune disease in the absence of an organism
What are the four tube colours for blood collection and what do the colours mean?
Red – no anticoagulant
Yellow – gel – makes the coagulation occur faster Purple – potassium EDTA
Grey – fluoride oxalate (poison)
Which tubes for the following:
1) U&Es
2) Glucose
3) HBA1c
4) TFT
5) Liver function tests
U&Es: Serum in yellow/red top
Glucose: Plasma in grey top
HBA1c: Plasma in purple top
TFT: Serum in yellow/red top
LFT: In yellow/red top
What are the purple cap bottles used for?
Potassium EDTA keeps the cells alive It is used when measuring cell counts or anything in general to do with the cells
What are the grey cap bottles used for?
Fluoride oxalate kills the red blood cells – this is used for measuring blood glucose because live red blood cells will consume the glucose
Which bottle is used for measuring HbA1c?
Purple Top – potassium EDTA
What is serum and what is it useful for measuring?
When blood clots and you remove the clot you are left with serum
Serum contains electrolytes but NO clotting factors
How is gel designed so that it separates serum from the rest of the blood?
It is more dense than serum but less dense than cells so it separates the serum from the cells when centrifuged
What is contained in plasma?
Serum and the clotting factors
What can skew the electrolyte measurements of the serum?
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
What does the blue top mean?
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
What is the blue top used to measure?
Prothrombin time (PT) - measures integrity of extrinsic system
Active partial thromboplastin time (APTT) - measures integrity of intrinsic system
what are the main anticoagulants used?
EDTA and heparin
what is the effect of using anticoagulants in the blood sampling?
Clotting factors remain unused so the plasma can be separated from the RBCs with CFs still there
What is used to measure clotting factor levels?
Blue top reversible
When should you contact a chemical pathologist? [3]
Need for rapid centrifugation out of hours
Measuring labile hormones like insulin
Urgently need CSF glucose and protein measurements (meningitis rapidly consumes glucose)
What is creatinine a marker of?
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
What is urea a marker of?
High levels indicate dehydration
It is also excreted by the kidneys
(Dehydration indicated especially if creatinine levels are normal)
