Renal Drug Dosing Flashcards
What describes the rate at which the kidneys filter blood?
glomerular filtration rate (GFR)
GFR is a measurement of what?
kidney function
Is GFR precise?
no, but it gives us an idea
GFR is important in (…) and (…)
- drug selection
- dosing
What are the equations to assess eGFR (estimated glomerular filtration rate)?
- MDRD (modification of diet in renal disease study equation
- CKD-EPI (chronic kidney disease epidemiology collaboration equation)
What equation is used to assess CrCl (creatinine clearance)?
cockroft-gault equation (not precise but helpful)
How can you obtain a precise measurement of creatinine clearance?
a 12 to 24 hour urine collection
What measures how much creatinine is cleared by the kidneys?
C-G equation
What uses several factors to create an estimation of filtration rate?
- MDRD
- CKD-EPI
What equation underestimates GFR?
MDRD
What is this equation and what is it used for?
- C-G equation
- measures CrCl
Women don’t make as much (…) as males
creatinine
The C-G equation (…) GFR due to active secretion but (…) in elderly
- overestimates GFR
- underestimates in elderly
What are some considerations for the C-G equation?
- muscle mass
- diet
- amputations
- burn
- pregnancy
- age
- must have stable renal function
- some drugs increase secretion
- overweight/underweight
African Americans have (…) muscle mass and produce (…) creatinine
- higher muscle mass
- more creatinine
People with more muscle mass will produce (…) creatinine, resulting in (…) creatinine clearance
- more creatinine
- increased creatinine clearance
People with less muscle mass will produce (…) creatinine, resulting in (…) creatinine clearance
- less creatinine
- reduced creatinine clearance
How does diet affect creatinine clearance?
- diets high in red meats or other protein sources may have increased creatinine levels → increased creatinine clearance
- vegetarians will have lower creatinine levels → decreased creatinine clearance
Amputees will have (…) creatinine levels → (…) creatinine clearance
- lower creatinine levels
- decreased creatinine clearance
Renal clearance may be (…) in patients with burn wounds
renal clearance may be falsely elevated
During pregnancy, renal clearance (creatinine clearance) (…) because blood volume and kidney function cause (…) creatinine to be filtered out of blood and passed into the urine
- increases
- more creatinine
CrCl (…) with age due to a reduction in muscle mass
decreases
Underweight individuals may not be producing enough (…) so they may have (…) creatinine clearance
- creatinine
- reduced
Obesity does not (…) secretion of creatinine, but we have mass of fat and mass of muscle involves that we are unsure of
increase
Why are age and weight important for determining CrCl?
they are both proportional to creatinine clearance
Adjusted body weight for CrCl does not work in which individuals?
body builders
How do you calculate ideal body weight in males?
50 + (2.3 * height in inches over 5 ft)
How do you calculate ideal body weight in females?
45.5 + (2.3 * height in inches over 5 ft)
In obese patients where their actual weight is 30% over ideal body weight, what do you need to use in your calculations?
adjusted body weight
How do you find adjusted body weight?
IBW + 0.4 * (actual-IBW)
If a pts serum creatinine level is normal, isn’t that good enough?
No, because there are a lot of things affecting creatinine levels
Describe normal CrCl evaluation
- GFR ≥ 90
- no evidence of kidney disease
Describe stage 1 CrCl evaluation
- GFR ≥ 90
- some evidence of kidney damage with normal GFR
If body weight is more than 30% ideal body weight, what do you use?
adjusted body weight
Normal CrCl is in the (…)
100s
Make sure you know if drug is dosed based on (…) or (…)
- CrCl
- eGFR
If a drug is dosed based on CrCl, what will you use?
- CrCl equation (C-G equation)
