Pathophysiology: Quantification of Renal function

Question 1

Which estimates equation should be used to adjust medication doses in a patient with CKD?

Answer 1

• Cockcroft-Gault Equation

Question 2

What estimation equation should be used when diagnosing CKD?

Answer 2

• MDRD
  or
• CKD-Epi equation

Question 3

Which estimation equation can be used to adjust medication doses in a patient whose SCr is not stable?

Answer 3

• None of the above

Question 4

Why do we need to quantify renal function

Answer 4

• to identify and treat renal disease
• to properly dose medications

Question 5

How to quantify renal function

Answer 5

• Blood tests: Blood Urea Nitrogen (BUN), Serum Creatinine (SCr)
• Equations that estimate renal function: Cockcroft-Gault, MDRD, CKD-Epi

Question 6

Blood Urea Nitrogen (BUN)

Answer 6

• breakdown product of protein
• excreted by kidneys
• increased when pts have: dehydration and/or excessive protein
• elevated BUN: NOT diagnostic for renal disease

Question 7

Serum Creatinine (SCr)

Answer 7

• degradation product of creatinine in muscle
• depends on age, gender, muscle mass, medications, exercise and diet
• primarily eliminated by glomerular filtration
• SCr accumulates in blood as glomerular filtration decreases
• not sensitive to rapid or acute changes in glomerular filtration
• takes 1-2 days for SCr to increase

Question 8

Glomerular Filtration Rate (GFR)

Answer 8

• rate at which blood is filtered through glomerulus
• cannot be measured in clinical practice
• it is estimated using equations: Cockcroft-Gault equation, MDRD equation, and CKD-Epi Equation

Question 9

Cockcroft-Gault equation

Answer 9

• incorporates SCr, age, sex, and age
• used to adjust drug regimens in pts with stable renal function and/or CKD
• inaccurate in pts with AKI: because it takes 1-2 days for SCr to increase after a decrease in GFR

Question 10

CKD-Epi Equation

Answer 10

• preferred equation for diagnosing CKD in pts with stable renal function and/or CKD
• inaccurate in pts with AKI
• formerly included race

Question 11

Modification of Diet in Renal Disease (MDRD) equation

Answer 11

• can be used to diagnose CKD
• inaccurate in pts with AKI
• incorporates SCr, sex, age and race

Question 12

Cockcroft-Gault equation

Answer 12

CrCl = [(140-age) * Ideal Body weight] / [SCr*(72)]

• multiply by 0.85 if female

Question 13

Ideal body weight formula

Answer 13

Female: 45.5 + (2.3 inches >60)

Male: 50 + (2.3 inches >60)