Renal Assessment (eGFR and PAH) Flashcards
what does a plasma clearance test test
the ability of the kidney to clear the plasma of various substances. it tells you the amount of plasma cleared off a substance NOT the quantity removed from plasma
what is the unit of plasma clearance
mls/min
true/false inulin is reabsorbed into the bloodstream
false - once filtered at glomerulus it remains in the tubule an 100% is excreted
if the GFR is 100ml/min and 100% of inulin is excretion, what is the unulin plasma clearance
100ml/min
what substance is used to estimate GFR
creatinine
true/false the relationship between plasma creatinine and GFR is linear
false - it plateaus between 50% and 100% GFR
what is normal GFR
100ml/min
a substance is all reabsorbed, such as glucose, has a plasma clearance of…
0ml/min
whats the plasma clearance of urea like
about half and half reabsorbed excreted so clearance is 50ml/min
if someone has GFR of 60ml/min what’s the maximum their plasma clearance of a substance could be
60ml/min
how does creatinine plasma clearance tell you about GFR
in a nephron creatinine should all be excreted. So by finding the plasma clearance of creatinine that tells you the amount of blood that the glomerulus filters/min
what does PAH tell you
the renal (plasma) blood flow
what does PAH stand for
para-amino-hippuric acid
how does PAH work to tell you renal plasma flow
it’s freely filtered at the glomerulus and the remaining PAH is actively secreted into the tubule so >90% of administered PAH is cleared
how is a substance with a greater clearance than inulin/creatinine is dealt with at the kidney
more is secreted into tubule ontop of what was freely filtered at the glomerulus
