1 / 12

Estimation of Kidney Function

Estimation of Kidney Function. Richard C. Walls 07-16-2013. Importance of Kidney Function. Kidney responsible (in part/whole) for excretion of many medications from the body t 1/2 of renally cleared medications prolonged with decreasing kidney function

heidi
Download Presentation

Estimation of Kidney Function

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Estimation of Kidney Function Richard C. Walls 07-16-2013

  2. Importance of Kidney Function • Kidney responsible (in part/whole) for excretion of many medications from the body • t1/2 of renally cleared medications prolonged with decreasing kidney function • Vancomycin: 5-11 hours w/normal function • Vancomycin: 8-10 days in ESRD • Potential for medication error • Drug accumulation & toxicity • Overly rapid clearance & subtherapeutic doses

  3. Importance of Kidney Function • Medications often require dose adjustment when eGFR < 60 • ≈40% of adults >70 years old have eGFR < 60 • This population uses 34% of all prescription drugs

  4. Estimating Kidney Function • Creatinine • Freely filtered • Minimally reabsorbed • Some secretion • Creatine Clearance estimates glomerular filtration rate • 24-hour urine collection gold standard • Time consuming • Logistically difficult

  5. Estimating Kidney Function • Equations estimating CrCl based on SCr alone desirable for convenience • Cockcroft-Gault Equation • FDA reports 1998-2007: CG equation specifically mentioned as the basis for 25% of renal adjustments for drugs reviewed • In elderly patients w/SCr < 1.0, common practice is to round SCr to 1.0 to compensate for reduced Cr production

  6. Estimating Kidney Function • Modification of Diet in Renal Disease (MDRD) • Designed and tested to more accurately estimate GFR than CG • eGFR≈ 186a* Scr-1.154* Age-0.204(*1.212 if black)(*0.742 if female) • Chronic Kidney Disease Epidemiology Study (CKD-EPI) • eGFR≈ 141 * min(,1)α* max()-1.209* 0.993Age (*1.018 if female)(*1.159 if black) • κ = 0.7 for females; 0.9 for males • α= -0.329 for females; -0.411 for males • More representative of actual GFR than MDRD in GFR > 60 • Recently National Kidney Disease Education Program has recommended eGFR equations be used interchangeably with CG for CrCl estimation

  7. Dowling Study • Objective: To evaluate how accurately different estimates of renal function reflect actual creatinine clearance. • Retrospective review of data collected as a part of the Baltimore Longitudinal Study of Aging

  8. Dowling Study • CrCl estimated/measured via • Measured 24-hour creatinine clearance (mClCr) • Cockcroft-Gault (CG) • Cockcroft-GaultSCr < 1.0 rounded to 1.0 (r-CG) • Modification of Diet in Renal Disease (MDRD) • Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) • Estimates compared for • Bias from mClCr • Variance ratio to mClCr • Dosage discordances from CG labeling

  9. Dowling Study - Population • Patients: 269 total • 140 women • 129 men • Age, yrs: 81 ± 6 • SCr: 1.1 ± 0.4 • 103 subjects < 1.0 • Avg 8.0 ± 0.1 • Race: 85% white • BMI • Only 28 patients > 30 • No patients > 40 • Overt signs of renal failure/dialysis excluded

  10. Dowling Study - Results

  11. Dowling Study - Results • Patients w/SCr < 1.0

  12. Dowling Study - Results

More Related