Monday, April 11, 2011

When the GFR is zero how fast does the creatinine rise?

How do you get a GFR of zero?
Bilateral bathtub nephrectomy
In my clinical experience when the GFR approaches zero the creatinine goes up between 1 and 2 mg/dL everyday.

However ai was working out a story problem for an acute renal failure and when I calculated how much the creatinine would rise it was 3.3 per day. Here is how I calculated this:

  • Total body creatinine: 420 mg
    • This assumes that creatinine is equally distributed through out total body water. So 42 liters (60% of 70kg) times 1 mg/dl times 10 dL per liter
  • New creatinine: 1400 mg
    • 20 mg of creatinine generation per kg body weight, 70 kg body weight
  • New total total body creatinine 1820 mg
    • add the first two figures
  • New creatinine: 4.33 mg/dL
    • Divide the total body creatinine (1820 mg) by total body water (420 dL):

Did I do my calculation wrong? The total body creatinine calculation of 420 mg seems awfully low, especially if muscles create 1400 mg of new creatinine everyday.

Picture by The Doctr
Related Posts Plugin for WordPress, Blogger...