Drug Dosing in Renal Disease Flashcards
What is the pathophysiology of SCr?
Creatinine is produced in the liver -> stored in muscle as creatinine phosphate -> released as creatinine -> kidney
How much of SCr is filtered/secreted?
90% filtered
10% secreted
What factors are SCr affected by?
Age
Gender
Diet
Body habitus
Why is SCr used as a standard?
Decreased variability among laboratories
Use of isotope dilution mass spectrometry (IDMS)
Improve reliability of eGFR results
What is the pathophysiology of Cystatin C?
Freely filtered by glomerulus -> reabsorbed by tubules -> catabolized by tubular epithelial cells
What is the role of cystatin C?
Clinically undefined
Confirmation of CKD diagnosis
What are the limitations of cystatin C?
Expensive
Not standardized
What kind of renal function can drug dosing equations be used in?
Stable
What are the limitations of Cockcroft-Gault equations?
Use of SCr Overestimates renal function Not re-expressed Use in elderly patients Use in obese patients
What are the clinical pearls of Cockcroft-Gault equations?
Used most frequently in practice (even in patients w/unstable renal function)
Preferred method for drug dosing
What are the limitations of MDRD equations?
Use of SCr
Underestimates GFR
Not validated for drug dosing
Not tested in elderly patients, low weight patients or some ethnic groups
Less accurate at higher GFRs (reason for > 60 instead of exact number)
What does Cockcroft-Gault measure?
ECC or CrCl
What does MDRD measure?
GFR
What does CKD-EPI measure?
GFR
What does Salazar-Corcoran measure?
ECC or CrCl
