GFR and ERPF Flashcards
extraction ratio (ER)
fraction of a substance removed from plasma during one circulation through the kidney
- urine elimination and renal retention
ER 1 = ?
drug completely removed from circulation in single pass through kidneys
ERPF RP agent
MAG3
formula for ER
([A]-[V])/[A]
a - arterial conc of substance
v - venous conc of substance
UV/P method measures…
renal excretion by measuring amt of substance in urine and the volume of plasma cleared of the substance
what is the formula for renal clearance?
(ml/time) = ([Urine] * urine vol/min)/[Plasma]
what is the gold standard for GFR?
inulin
slope of line D
rate of clearance
indications
- serial monitoring of function in renal disease and those undergoing treatment with nephrotoxic drugs
- following post kidney transplant and donation
how is camera GFR done?
- syringe counts before injecting patient with camera
- immediately inject and image patient
- post injection syringe counts with camera
how far is the syringe usually placed from the camera?
20-30 cm away
imaging is done for how long with the gate’s method?
6-30 mins
dose when doing camera GFR?
111 MBq DTPA
4 GFR blood sampling techniques
- single sample test
- two sample test
- multi sample test
- multi sample with urine test
single sample test
blood drawn 3 hrs post RP
cpm compared to that administered
2 sample test
blood drawn at 1 hr and 3 hrs post RP admin
multisample test
blood draw at specific intervals
which is the most accurate method to determine GFR
multisample test with urine
plasma counts high = GFR is ___
low
plasma counts low = GFR is ___
high
4 broad stages of GFR measurement
- tracer prep
- tracer administration
- blood sampling
- sample counting
dose of RP for blood sampling technique
555 MBq DTPA
drawing blood 30 mins too early causes the GFR to be…
falsely low
drawing blood 30 mins too late causes the GFR to be…
falsely high
normal GFR for men
renal plasma flow
amount of plasma arriving for clearance at the glomerulus
