Estimating the glomerular filtration rate in obese adult patients for drug dosing

Adv Chronic Kidney Dis. 2010 Sep;17(5):e53-62. doi: 10.1053/j.ackd.2010.05.010.

Abstract

One-third of adult Americans are currently classified as obese. Physiologic changes associated with obesity can potentially alter the clearance of commonly used drugs. Clearance of certain drugs by the kidneys occurs primarily through glomerular filtration and tubular secretion. Obesity has been associated with glomerular hyperfiltration, whereas obesity-related effects on tubular secretion are not well characterized. Estimation of the glomerular filtration rate (GFR) is currently performed using serum creatinine using the Modification of Diet in Renal Disease (MDRD) equation. However, drug dosing guidelines are often based on creatinine clearance (CLcr) using the Cockcroft-Gault equation as a surrogate of GFR. There is a lack of consensus on the most appropriate method for estimation of GFR or CLcr in patients with obesity. The controversy relates to the use of 2 body size descriptors that confound these equations. The Cockcroft-Gault equation relies on total body weight and so overestimates GFR in patients with obesity. The MDRD equation indexes GFR based on a normalized body surface area, that is, mL/min/1.73 m(2). Conversion of MDRD estimated GFR to non-normalized body surface area overestimates GFR in patients with obesity. The current review explores current approaches and controversies to estimation of GFR and CLcr among obese patients in clinical practice. The role of the alternate body size descriptor, lean body weight to estimate CLcr in obese patients is reviewed.

Publication types

  • Review

MeSH terms

  • Adult
  • Body Weights and Measures / methods
  • Creatinine / blood
  • Glomerular Filtration Rate*
  • Humans
  • Kidney / pathology
  • Kidney Diseases / blood
  • Kidney Diseases / etiology
  • Kidney Diseases / physiopathology
  • Kidney Diseases / urine
  • Obesity / blood
  • Obesity / complications*
  • Obesity / epidemiology
  • Obesity / physiopathology
  • Pharmaceutical Preparations / administration & dosage*
  • Pharmaceutical Preparations / urine
  • Pharmacokinetics
  • Regression Analysis

Substances

  • Pharmaceutical Preparations
  • Creatinine