Renal Calculations

Question 1

GFR

Answer 1

Clinically assess the degree of kidney impairment

Question 2

Creatinine Clearance Equation

Answer 2

CrCl (mL/min) = (140-age) x (Ideal body weight in kg) / (72 x SCr) x (.85 if female)

Question 3

When to use adjusted body weight in Creatinine clearance equation

Answer 3

If actual body weight is greater than 30% above ideal body weight

Question 4

When to use actual body weight

Answer 4

When actual body weight is less than ideal body weight

Question 5

Creatinine

Answer 5

Byproduct of creatine metabolism, from skeletal muscle and dietary meat intake

Question 6

Limitations of Creatinine clearance

Answer 6

Affected by certain drugs (trimethoprim, cimetidine, dolutegravir)
Consuming large cooked meats = rise
Exercising = acute rise
Frailty: decreased muscle mass (tiny old lady) = decreased breakdown = low creatinine
Amputees: less muscle and less movement as well

Question 7

Renal Dose Adjustments

Answer 7

GFR and CrCl are estimations, entire clinical picture and judgement required for treatment
Omitting a renal dose adjustment can cause increased therapeutic effect or ADRs