Blood tests Flashcards
what is the minimum daily water intake to maintain fluid balance
1100ml
Around 500ml water required for normal excretion of waste products in urine, with remaining losses coming from where?
insensible losses via skin in sweat, lungs in expired air and in faeces
The kidneys regulate water balance, with water being filtered, then resorbed in variable amounts depending primarily on
ADH
what is the normal reference range for sodium?
135-145 mmol/l
is inadequate oral intake of Na a cause for hyponatremia?
rarely
hypOnatraemia can present asymptomatically but name some possible symptoms
vomiting
drowsiness
headaches
seizures
what does hyponatremia go alongside?
volume depletion due to water loss/dehydration
what are 4 drug causes of low sodium?
antidepressants
diuretics
nsaids
carbamazepine
what is the most common reason for hypernatremia
impaired excretion
what symptoms do patients with high sodium present with that are shared with diabetes inspidus
polyuria
polydipsia
dehydration
drug causes are less common for hypernatremia but list some that may increase sodium levels
lithium
demeclocycline phenytoin
reference range for K?
3.4-5.0 mmol/k
list some non drug causes for hypokalemia
transcellular movement into cells
losses from GIT
losses from kidney
px with moderate hypokalemia are often asymptomatic but how might severe cases present
muscle weakness
depression
confusion
ecg changes
what ecg changes may be seen in hypokalemia
st or t wave depression
list some drug causes for hypokalemia
diuretics
insulin
corticosteroids
laxatives
salbutamol
hyperkalemia can be asymptomatic but fatal due effects on the heart, in what ways can it affect the heart
lowers membrane resting potential thus lowering action potential -> ventricular fibrillation and cardiac arrest
non-drug causes of hyperkalaemia
K goes from cells to ECF, CKD as cannot excrete K,
drugs causing hyperkalaemia
ACE/ARB i
spironolactone
K sparing diuretics
Urea reference range
3.1-7.9 mmol/l
urea levels vary with diet, rate of protein metab and what else?
GFR
low urea levels are uncommon and not cause for concern.
they are normal for what group?
normal pregnancy
why is urea monitoring esp required for highly protein bound drugs such with ntr such as digoxin or phenytoin?
toxcity can occur
when might urea monitoring be important?
when monitoring NTR drugs for toxicity
what are high urea levels >10 caused by
renal disease or decreased renal blood flow following shock or dehydration
normal creatinine range
75-155mol/l
what does creatinine show?
how the kidney is excreting as it is excreted unchanged and not reabsorbed by tubules
why is creatinine clearance a good indicator of gfr and therefore kidney function
creatinine undergoes complete glomerular filtration with little reabs from renal tubules
what does a doubled creatinine show?
GFR halved
a decline in eGFR represents decline in what?
renal function
an egfr above x means good clearance and therefore kidney function
90
what is the reference range for men for Hb?
115-165g/L
what is the reference range for women for Hb
112-160g/L
what is the primary role of hb
transport oxygen
good marker for anaemia
give one reason why women may have lower hb compared to men
menstrual losses
why might Hb be higher?
cancer or dehydration
what is the normal range for platelets?
150-450x10^9 /L
why are platelets good to measure
damage to vasculature is fixed by the aggregation of platelets to form plus and they act in initiation of coag process
rbc are produced in bone marrow under the control of
erythropoetin
what is erythropoetin released in response to
decrease in oxygen delivery
what does a high rbc mean
increased production in bone marrow due to hypoxia in eg chronic airway disease
what are reticulocytes?
immature RBCs
lifespan of normal rbcs
120 days
when will anaemia occur?
decreased production or increased removal of rbc
why might increased loss of RBCs occur?
haemolysis/ severe bleeding/haemorrhage
what do the reticulocytes do in response to low RBCs?
increases production
what is the mean cell volume
average volume of single RBC
3 ways that rbc can be characterised based on their size (anaemias)
microcytic
normocytic
macrocytic
what is macrocytic anaemia?
folate/b12 deficiency
what is microcytic anaemia
iron deficiency
what is the term given to an elevated number of white cells
leucocytosis
why can white blood cell counts be raised
infection, inflammation, leukaemia
A decreased WCC is called what?
leucopenia
give some different causes for leucopenia
chemo
bone marrow disorders
b12 or folate deficiency
liver disease
IS disease
life span and basic function of neutrophils
7 hrs and immune defences
life span and basic functions of eosinophils
8-12 days and parasitic defence
life span and basic function of basophil
few hrs to days and inflammatory response
life span and basic function of monocytes
3 days and immune surveillance
life span and basic function of b cells
years as memory cells and antibody production
life span and basic function of t cells
years as memory cells and cellular immune response
true or false, there isnt a single test that will give a good estimate of liver function
true
the range for albumin is 34-50g/l and gives an indication of the synthesis of
hepatic proteins
albumin plays a role in maintaining X pressure of blood…
oncotic
what do chronically low albumin levels lead to?
in severe hepatic dysfunction can contribute to ascites
the range for bilirubin should be below 19mmol/l and is formed from the natural breakdown of what?
RBCs at end of their lifespan
what does increased bilirubin show
liver dysfunction
what can the prescence of increased bilirubin be seen as clinically
jaundice
ALT and AST are liver transaminases, what might raised levels indicate?
hepatocellular injury
death
what is ALP?
enzyme that transports metabolites across cell walls
where is ALP found?
liver, bile, kidney, intestinal wall
why can ALP be raised
cholestasis (reduced bile flow)
if alp is raised it is important to monitor the levels of gamma gt, what can a raised gamma gt be caused by
biliary epithelial damage
bile flow obstruction
alcohol
drugs
name one drug that might raise gamma gt levels
phenytoin
what is the primary site of synthesis for clotting factors
liver
a rise in which parameter would indicate that liver function is impaired and unable to make enough clotting factors
INR
what is the normal range for inr
0.8-1
lifespan of platelets
5-10 days
platelets made in bone marrow and released into blood where they play role in what?
coagulation, helping to stop bleeding when blood vessels are injured.
clump togetehr and aggregate = blood clot
where there is infection there will be inflammation but the same isnt true vice versa such as in the case of RA. What is the name of the test that can check for inflammation
CRP
what is CRP made by
liver
when can CRP be raised
after MI, inflammation, infection, after surgery, in sepsis
3 drugs that cause high potassium
ACEi, ARB, potassium sparing diuretics, heparin
3 drugs that cause low sodium
SSRI, diuretic, carbamazepine, NSAIDS
