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eGFR Calculator differences

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rick39522
rick39522

Hi.  For those that do not know me I am 68, single kidney (other removed due to cancer last July 31st).  Since removal my eGFR started at 35, went as high as 43, but last was 38 (after fasting 12 hours).  There is a eGFR calculator I found on the web from the national kidney foundation.  I found a very interesting difference.  Perhaps this is well known but it was news to me.  I used a creatinine level of 1.8 (it is not unusual for this to be he "normal" creatinine level for a person with a solitary kidney).  If I entered the 1.8, my age and calculated, the eGFR came out to be 38.  This is consistent with what my last blood test found.  HOWEVER.  There is an option to enter your own height and weight rather than just letting the calculator use the average for a man my age (which is how it is done by the labs, using an average, not my actual).  This time my eGFR came out to 44. Now both figures put me in the stage 3b category.  But it is a good example of how just using "normal" or "averages" to compare ourselves to can sometimes be misleading.

2 likes, 6 replies

6 Replies

  • marj01201
    marj01201 rick39522

    Posted

    Rick,

    Your point is well made. There are also minor differences across different eGFR calculator available online. For instance, I get higher eGFR numbers from calculators associated with Davila then that associated with the National Kidney Foundation. It's just another reason I try not to obsess too much over my actual data--the goal is basic stability or some overall improvement. That being said, I have another round of labs in another two weeks. I do notice my stress level elevating as the date for these labs comes closer🐶 So it is clearly easier said than done for me on managing my stress level related to all of this.

    Marj

  • rick39522
    rick39522

    Posted

    Marj we are twins, lol.  I too get so nervous when another test approaches.  No matter how much I tell myself it is silly and does nothing to change the results, my stress still increases.  You will see, thing will be stable for you.  I can just sense it. smile.   Of course you will let us know.
    • marj01201
      marj01201 rick39522

      Posted

      Thanks, Rick! And I'll certainly let everyone know. 

      Marj

  • tony78174
    tony78174 rick39522

    Posted

    in terms of misleading......, it's more important to remember the lttle 'e' in 'eGFR' means estimation, not exact. 

    that's why they are developing a new test, the current one is so inaccurate.

    • rick39522
      rick39522 tony78174

      Posted

      Yes Tony.  My point was not about accuracy.  It was about consistency.  When the exact same calculator can result in fairly substantial differences (38 vs 44) based on one slight data point difference (weight), it proves as you say the need for a new methodology.  I was not aware there is in development an attempt on a new more consistent method.  This will be great.  I know there have been attempts.  Such as the Gault method.  This produces numbers which are usually significantly higher than the current method.  I know ,most of my current doctors all say the same thing.  The eGFR is only used by them to see if the results go down over time, too significantly (they will always go down due to age).  But to pay attention to a number that we can trust.  Creatinine levels.  This requires no calculator, no height, weight, etc.  It just says here is how much is in your blood and here are the ranges that are a reflection of kidney performance.  If a new formula is develop, lets hope its a good one.  
  • Colombos
    Colombos rick39522

    Posted

    My take on this is, do not worry too much about eGFR, but monitor your creatinine level. Thank you, CS
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