Renal Drug Dosing

Question 1

What describes the rate at which the kidneys filter blood?

Answer 1

glomerular filtration rate (GFR)

Question 2

GFR is a measurement of what?

Answer 2

kidney function

Question 3

Is GFR precise?

Answer 3

no, but it gives us an idea

Question 4

GFR is important in (…) and (…)

Answer 4

1. drug selection
2. dosing

Question 5

What are the equations to assess eGFR (estimated glomerular filtration rate)?

Answer 5

• MDRD (modification of diet in renal disease study equation
• CKD-EPI (chronic kidney disease epidemiology collaboration equation)

Question 6

What equation is used to assess CrCl (creatinine clearance)?

Answer 6

cockroft-gault equation (not precise but helpful)

Question 7

How can you obtain a precise measurement of creatinine clearance?

Answer 7

a 12 to 24 hour urine collection

Question 8

What measures how much creatinine is cleared by the kidneys?

Answer 8

C-G equation

Question 9

What uses several factors to create an estimation of filtration rate?

Answer 9

• MDRD
• CKD-EPI

Question 10

What equation underestimates GFR?

Answer 10

MDRD

Question 11

What is this equation and what is it used for?

Answer 11

• C-G equation
• measures CrCl

Question 12

Women don’t make as much (…) as males

Answer 12

creatinine

Question 13

The C-G equation (…) GFR due to active secretion but (…) in elderly

Answer 13

1. overestimates GFR
2. underestimates in elderly

Question 14

What are some considerations for the C-G equation?

Answer 14

• muscle mass
• diet
• amputations
• burn
• pregnancy
• age
• must have stable renal function
• some drugs increase secretion
• overweight/underweight

Question 15

African Americans have (…) muscle mass and produce (…) creatinine

Answer 15

1. higher muscle mass
2. more creatinine

Question 16

People with more muscle mass will produce (…) creatinine, resulting in (…) creatinine clearance

Answer 16

• more creatinine
• increased creatinine clearance

Question 17

People with less muscle mass will produce (…) creatinine, resulting in (…) creatinine clearance

Answer 17

• less creatinine
• reduced creatinine clearance

Question 18

How does diet affect creatinine clearance?

Answer 18

• 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

Question 19

Amputees will have (…) creatinine levels → (…) creatinine clearance

Answer 19

1. lower creatinine levels
2. decreased creatinine clearance

Question 20

Renal clearance may be (…) in patients with burn wounds

Answer 20

renal clearance may be falsely elevated

Question 21

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

Answer 21

• increases
• more creatinine

Question 22

CrCl (…) with age due to a reduction in muscle mass

Answer 22

decreases

Question 23

Underweight individuals may not be producing enough (…) so they may have (…) creatinine clearance

Answer 23

1. creatinine
2. reduced

Question 24

Obesity does not (…) secretion of creatinine, but we have mass of fat and mass of muscle involves that we are unsure of

Answer 24

increase

Question 25

Why are age and weight important for determining CrCl?

Answer 25

they are both proportional to creatinine clearance

Question 26

Adjusted body weight for CrCl does not work in which individuals?

Answer 26

body builders

Question 27

How do you calculate ideal body weight in males?

Answer 27

50 + (2.3 * height in inches over 5 ft)

Question 28

How do you calculate ideal body weight in females?

Answer 28

45.5 + (2.3 * height in inches over 5 ft)

Question 29

In obese patients where their actual weight is 30% over ideal body weight, what do you need to use in your calculations?

Answer 29

adjusted body weight

Question 30

How do you find adjusted body weight?

Answer 30

IBW + 0.4 * (actual-IBW)

Question 31

If a pts serum creatinine level is normal, isn’t that good enough?

Answer 31

No, because there are a lot of things affecting creatinine levels

Question 32

Describe normal CrCl evaluation

Answer 32

• GFR ≥ 90
• no evidence of kidney disease

Question 33

Describe stage 1 CrCl evaluation

Answer 33

• GFR ≥ 90
• some evidence of kidney damage with normal GFR

Question 34

If body weight is more than 30% ideal body weight, what do you use?

Answer 34

adjusted body weight

Question 35

Normal CrCl is in the (…)

Answer 35

100s

Question 36

Make sure you know if drug is dosed based on (…) or (…)

Answer 36

1. CrCl
2. eGFR

Question 37

If a drug is dosed based on CrCl, what will you use?

Answer 37

• CrCl equation (C-G equation)