Hi!
Elderly people have a decrease in creatinine clearance (CrCl), which means an increase in serum Cr. It is observed that annual rate of this decrease in CrCl is approximately 1 ml/min. after the age of 50 years.
Therefore, it is important to calculate the dose and dosing intervals of nephrotoxic drugs (eg., aminoglycosides) in these patients in order to prevent the precipitation of ARF.
In general,
CrCl <100 ml/min is abnormal.
However, CrCl <10 ml/min signifies the onset and worsening of acute renal failure.
Note -
• GFR is directly proportional to CrCl.
• GFR decreases by age, but not always accompanied by rise in Cr.
• Cockcroft-Gault formula is commonly referred to for calculating CrCl.
CrCl = (Ucr × V)/Pcr (~GFR)
• Double the Cr = Half the GFR.
Note that those patients with signs of worsening diabetes and resulting glomerulopathies, an increase in both GFR and CrCl is seen, which thus causes hyper filtration injury.
That's all
- Jaskunwar Singh