Why is my lab gfr different from the gfr my nephrologist quoted?

[Apple12]

My recent June lab report shows a egfr of 24 and creatinine of 2.83. However in May my nephrologist told me my labs show that my creatinine was 2.8 (same as the June report) and my gfr is 40. Why are the gfr numbers different while the creatinine number are the same? When I imputed my age, sex, race and creatinine number (2.83) in devitas *sp website gfr calculator it coincides with my recent lab report gfr of 24.

[Bassetmommer]

Hi Apple,

You would have to ask the doctor why he said that. Do you get a copy of the lab which includes the calculated GFR?

[Apple12 in reply to Bassetmommer]

Hi Bassetmommer. Yep, I got a copy of the June report. I don't have a copy of May's. The labs for May were done in the hospital where I found out about the CKD. I did see on line that the MDRD4 equation to calculate a gfr reported a creatinine level of 2.8 would be 40 gfr. Perhaps that's the equation set he used. Thanks

[FThomp in reply to Apple12]

Hi Apple? Did you ever get more clarity on this? I’m having a similar question myself bc my labs show a different gfr than most calculators. When I use a calculator from mk for davita it’s in the 90’s or 80’s but my lab work says low 70’s even 67

[Apple12 in reply to FThomp]

Hi FThomp, unfortunately no. My nephrologist doesn't seem to have an issue with it, so I guess that's it. Although I am seeing information that suggests these "calculations methods" are flawed and need to be revamped quite a bit.

[FThomp in reply to Apple12]

Same. My research found that most labs still use old formulas and different ones today that are outdated. I’m glad people like us remain proactive and positive about these things