lab diagnostic methods

Question 1

what tests can a doctor do

Answer 1

FBC, ESR (erythrocyte sedimentation rate) and CRP (made by liver) (both indicate inflammation

Liver function testsmes leek out)

urea and electrolytes eg sodium

stool culture

thyroid function tests

Question 2

different tubes and anticoagulants present

Answer 2

red top has none
,yellow top has gel to speed up clot (both used for urea and electrolytes, thyroid and liver function tests)

purple top has potassium EDTA (used for FBC or HBA1C, NOT electrolytes, as has K+)

grey top has poison fluoride oxalate (used for blood glucose, prevents RBC from using glucose and lowering it)

Question 3

serum vs plasma

Answer 3

yellow/red tops are serum, as clots form, which uses up all clotting factors, leaving serum ie no clotting factors

anticoagulants like EDTA/heparin prevents use of clotting factors, and if centrifuged separates blood into RBC and plasma ie HAS clotting factors

Question 4

possible causes of low Na and high K

Answer 4

adrenal failure (less aldosterone), and haemolysis (RBC have lots of K, so release it upon death)

Question 5

renal function

Answer 5

look at Na/K, but ALSO urea and creatinine- if both high, indicates renal failure, if urea high but creatinine NORMAL, indicates dehydration (no problem with GFR, problem with tubules)

Question 6

liver function

Answer 6

albumin

bilirubin (gives faeces brown colour- if stool pale and urine dark, indicates issue with liver- bilrubin high, should be in faeces but in bloodstream instead)

alkaline phosphate (indicates obstruction of bile duct)

ALT/AST (indicates inflammation of liver, often viral hepatitis)

Question 7

cardiac enzymes

Answer 7

leakage of these indicate heart attac- troponin, creatine kinase, AST and lactate dehydrogenase