Reason for GFR level to fluctuate from 20 to 57?

I have no medical training, so take this for what it's worth--just one experience to give you something to think about. My son's GFR is usually 80. He passed several kidney stones in the last week, during which time they measured GFR again. It was lower while he was trying to pass the stones. The Dr very quickly explained that the number fluctuated for him because the stone was causing the urine to back up into the kidneys.

@aihtnyc & @jsdms welcome both of you to Mayo Clinic Connect. Regarding the GFR, these values can vary greatly for a number of reasons (hydration, other conditions & ailments, the particular lab that is used to perform the tests ….. ) One GFR level is not as important as considering the overall trend over time. If you have a need of tracking the GFR it is best to stay with one provider / lab and get the draw done when all other factors are as consistent as possible. If you don’t mind sharing, what are your reasons for following the GFR?

Like jsdms, I have no formal medical training so please understand that my comments come from personal experience. I have had Chronic Kidney disease since 2003 (although it was not mentioned by any of my doctors until I asked about the low eGFR reading on my annual blood test in 2019. I then went back and looked at my blood test results as far back as I have them which is 2003) My Creatinine and eGFR have been consistent with CKD Stage 3a for 20 years, during which time my eGFR test results have fluctuated between 47 and 61.
The lower readings occurred when I was dehydrated or had some other source of illness at the time of the test. The eGFR 47 reading occurred when I had a bladder infection. The 61 reading occurred when I was recently in the hospital recovering from a bicycle accident in which I broke both my left arm and left leg. While in the hospital daily blood tests were done and the five readings for my eGFR were:
Sep 11, 2023 61 mL/min/1.73m*2
Sep 10, 2023 56 mL/min/1.73m*2
Sep 9, 2023 60 mL/min/1.73m*2
Sep 8, 2023 59 mL/min/1.73m*2
Sep 7, 2023 59 mL/min/1.73m*2

You can see from these results that a variance of 5 ml occurred between Sep 10 - Sep 11. The tests were done every morning before breakfast, and I was on an IV drip so my hydration was relatively stable. I am guessing that the low reading on Sep 10 was due to some alarming news that my doctor gave me on the afternoon of Sept 9th. Stress can also affect your kidney function. Thankfully the alarming news proved to be unfounded with further testing.

At my follow-up appointment with my primary care physician on Oct 17, 2023
my eGFR reading was 55 which is where it is most often during my regular blood tests.

I have read that an acute kidney injury (AKI) can cause a sudden significant drop in eGFR, and once the cause of injury has been addressed the kidney function as shown by eGFR improves - but usually not to the level of function that was standard before the AKI.

I hope you will find this information helpful in answering your question about eGFR levels.

@aihtnyc as you have read, there can be reasons for fluctuations in eGFR [kidney function]. Dehydration, having an infection, reaction to a medication, an underlying comorbidity that is acting up can all be factors. Can you recall if any of these have happened during these test results?
Ginger

Hello my first labs were done in Jan this year. My GFR was at 39 then six months later my blood pressure wasn't being managed and I went to the ER from high blood pressure 245/115 and they blood test my GFR went down to 27.1 stage 4 kidney disease. Then I started seeing a new Doctor in just two days she ran blood test GFR went down again 25. I need answers this to me sounded crazy I don't see my nephrologists until next month I'm worried by then it'll go down more. My blood pressure is being more managed and I now walk and drink water daily do any think your GFR can go back to stage 3 after being at stage 4

@roz27 Welcome to Mayo Clinic Connect.

Yes, it is possible to have your eGFR rebound back to more acceptable levels. But it takes a lot of work on your part, to be honest. You say your high blood pressure is more managed. It is not an instant reversal, and sometimes if the damage was done it may not be able to recover.

Good solid exercise, following a sound renal diet, taking the appropriate medications that your medical team suggests will help a lot. What is a good renal diet? Limiting salt, processed meats, phosphorous, potassium, calcium, NSAIDS [like Alleve], watching your protein intake. There are several helpful renal guidelines:
from the National Kidney Foundation: https://www.kidney.org/nutrition
from DaVita Kidney Care: https://davita.com/diet-nutrition/
Ginger

My creatinine (a protein used to measure GFR) and eGFR levels were normal range for years, until I got norovirus in December, 2023 while I still had long covid. My eGFR went from 77 in Sept. to 35 in Jan., likely due to rapid onset severe dehydration, high temperature, and inflammation. Covid did result in spikes in high blood pressure, but my resting BP is normal range and no risk factors for kidney disease other than being 70 (active, normal weight, already on a renal diet because of hubby, etc). Going on 2 years later my eGFR ranges from 32 to 45 and my kidney biopsy in June showed moderate scarring of my renal tubes and glomera (filtering cells). I didn't tolerate Lisinopril so one month ago I started 10 mg/day Jardiance, a pricey SLGT2 inhibitor. So far it has changed my average BP from 119/69 to 108/73 (systolic is more important than diastolic for heart/kidney health). So far no change in creatinine levels (which are what eGFR reflects), but that can take several months according to the doctor. Other than some fatigue, I don't have AKI or CKD symptoms. SLGT2 inhibitors don't seem to cause symptoms in me. Diet, avoiding stress, and getting enough aerobic and resistance exercise is important.

@roz27 I was in a similar situation as you. In 2005 I found out I had minimal - moderate kidney disease. It wasn’t called CKD and wasn’t given a stage #. In 2016 I learned about eGFR and mine would fluctuate between 14 - 44. There are so many variables that affect the GFR. Any one test isn’t very meaningful. The trend over time is more useful. At some point I got a nephrologist. He told me that I basically had stage 4 CKD. He put me on meds for blood pressure, referred me to a renal dietician to learn about helpful renal nutrition requirements and he monitors my kidney function labs. I see him twice a year for office visits alternated with visits to his nurse practitioner. @gingerw described great things to work on towards reversing CKD. These are the things I did. Now my nephrologist says that I am stage 3 CKD. My GFR is in the low 30’s. It does vary however. I recently had a lengthy visit to the ER for something seemingly unrelated. While there the GFR dipped to 27. So once you know you have CKD follow the suggestions listed here, get providers to help monitor & manage things and do the best you can and try not to stress over temporary variations.

This is helpful for me as I try to maintain Gfr of 44 to 46 since 2020 on my own...when I was told by "kidney" doc over the phone(never saw him {covid restriction]) that lots of people live on 1 kidney and that the measurements were quite loose and not to worry ...but call if needed....which I never did as my gp in 2023 said it was not needed.(she has since retired) I have been able to organize blood testing every 3mo. To track my A1C(pre-diabetic) and GFR with my new NPJune (2025) who so far has been agreeable to keep ordering the tests every 3mos.(had to convince her first) I am a full time professional artist(painter) with regular exhibitions of my work and I find all this stuff hard and discouraging.I will be 87 in Feb and wondering if I should bother with all this stuff if I am likely to be dead and broke by 90? Friends (much younger) say oh don't bother with all this stuff....eat, drink enjoy yourself....this seems like weak minded thinking...but if I end up on a kidney machine anyway and not creating (I would not be wanting to live). I hate that this is taking up space in my brain when time is precious and there are paintings to do...Thinking I should retreat to my cave and isolate.Sorry this has turned into a rant...how does one handle non-serious of indifferent friends/family. I am grateful for my good friends and family. Peace be with us

I can sympathise. Friends and fun are great but one can't enjoy them as much if ill. I'm already on a very restricted diet due to celiac and collagenous colitis, so avoiding alcohol, caffeine, sugar, and salt, and drinking more water is easy. I would say eat healthy, drink enough water, and enjoy yourself. It is unlikely they know what you are dealing with and impacts on your health. Great that you have been so successful on managing your health.