Session 2- Clearance Flashcards
Normal GFR?
90-120ml/min
GFR in pregnancy?
50% increase, 130-180ml/min
Who can grow new nephrons?
Children
What do adults do instead of making new nephrons?
Compensatory hypertrophy
After age 30 how much does GFR decline per year
6ml/year
What is eGFR appropriate for measuring?
CKD
What is eGFR not appropriate for?
In pregnancy, AKI, children/elderly, GFR >60ml/min
What does eGFR account for
Age, sex, black
Problem with creatinine?
Individual variation- if more muscly make more creatinine
Diet- eat more meat then more creatinine
Secretion- some actively secreted in PCT so GFR is overestimated by 10%
What’s good about creatinine?
Endogenously made (unlike inulin), not reabsorbed, freely filtered at glomerulus
What GFR measure can you use for children or renal transplant?
51 Cr-EDTA- radioactive, inject, 3 bloods.
Creatinine secretion ________ with worsening GFR
Increases (so underestimates renal failure)
Using creatinine _______ GFR
Overestimates
If GFR is low then serum creatinine _____
Increases
Baby GFR…
20ml/min
Renal clearance equation
Cx = Ux x V / Pax (arterial plasma)
Creatinine clearance is used clinically for…
Pregnant women
Ideal high creatinine person…
Black, bodybuilder, loves meat, on trimethoprim, eating creatine supplements
Ideal low creatinine person….
Old, low muscle mass, female, hispanic/indo-asian, vegetarian
True GFR can be measured with
Inulin
You can have some decline in kidney function but no change in GFR…how is this possible?
Compensatory hypertrophy
Little old lady will have lower serum creatinine- why is this a problem?
eGFR equations use serum creatinine levels so GFR will appear lower
