Glomerular Filtration Rate(GFR) Flashcards
what 2 things are used to assess glomerular function
GFR and proteinuria
why is inulin not an ideal marker for GFR
its not endogenous and not easy to measure
why is urea not an ideal marker for GFR
it doesn’t appear at a constant rate, it is reabsorbed at the renal tubules and it undergoes extra-renal elimination
why is creatinine not an ideal marker of GFR
it is secreted into the renal tubule
describe the limitation of creatinine as a GFR marker
creatinine isn’t sensitive to changes in GFR until GFR is quite low
what is the solution to the limitations of creatinine as a GFR marker
urinary creatinine clearance, because it is sensitive to changes in GFR at higher levels of GFR, unlike creatinine alone
describe what the urinary creatinine clearance is
the volume of blood that’s ‘cleared’ of creatinine per minute by glomerular filtration
what 3 things are measured in order to get urinary creatinine clearance
creatinine level in blood and in 24-hour urine collection, as well as volume of urine produced
what is the calculation used to get urinary creatinine clearance
[urine creatinine conc. x urine volume]
divided by
[serum creatinine conc. x duration of collection(mins)]
what does measurement of serum creatinine reflect
kidney function(ie GFR) but also amount of creatinine produced a day
what factors can influence the amount of creatinine someone produces a day
key confounders = muscle mass, diet,
proxies used at day-to-day = age, sex, ethnicity
is urinary clearance a measurement that can only be used for creatinine
no can be used for many things, eg drugs
what staging system is used for eGFR
CKD(Chronic Kidney Disease) stage, stage 1-5, 1 being best 5 being renal failure
what does eGFR mean
eGFR = estimated Glomerular Filtration Rate
what is used if it is essential to get accurate GFR reading
51Cr-EDTA clearance
