What is the role of age in estimating glomerular filtration rate (GFR) in chronic kidney disease (CKD), and how is GFR calculated in elderly patients?

Updated: Jul 21, 2021
  • Author: Pradeep Arora, MD; Chief Editor: Vecihi Batuman, MD, FASN  more...
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Answer

Age is an important consideration with respect to estimated GFR. In a 70-kg man aged 25 years, a serum creatinine value of 1.2 mg/dL represents an estimated GFR of 74 mL/min/1.73m2, but in a 70-kg man aged 80 years, that same value represents an estimated GFR of 58 mL/min/1.73m2. Thus, in a 70-kg, 80-year-old man, a serum creatinine of 2 mg/dL actually represents severe renal impairment, with an estimated GFR of 32 mL/min/1.73 m2 as measured by the MDRD equation.

Therefore, in elderly patients an estimated GFR must be determined using a formula such as the MDRD equation, which includes age as a variable. This will allow appropriate adjustments of drug dosing and avoidance of nephrotoxins, in patients who have more extensive CKD than would be suggested by the serum creatinine value alone.


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