I hate to brag (no, actually, I’m proud of it!), but today I had my best creatinine and eGFR test results since I donated my kidney to my son 14 years ago. Creatinine reflects the amount of toxins in the blood (lower is obviously better), and GFR is an overall measure of kidney function (the clinical term is glomerular filtration rate). The little “e” before GFR just means estimated. The exact measure requires a 24-hour urine collection, which I vividly remember doing for my donor evaluation.
For the estimate, they use a formula based on creatinine, age, sex, and a few other factors. My creatinine is 0.75 (normal is under 1.00 for females, and mine’s been under 1.00 for about the past 5 years but never this good)! My eGFR is 80 (normal is over 60). To give you an idea, kidney failure–meaning the imminent need for dialysis or transplant–is below 15.
Given that it’s natural for kidney function to decrease as we age, at 72 years old, I would expect mine to be lower. Plus, as a living donor, there’s no cause for concern even if it’s slightly under 60 (categorized technically as “stage 3 of kidney disease”).
Those stages are based on people with two kidneys and/or patients who are continually losing kidney function. So, I wasn’t at all concerned a few years back when my eGFR was 59 but my creatinine was under 1.00.
And now 0.75! So, if you or anyone you know is worried about living donors’ losing too much kidney function, please tell them about my results. (And, no, I don’t have a water bottle attached to me all day, though I’m not knocking those who do.)
I always tell potential kidney donors to keep an open mind but to do their homework and be as well informed about living donation as they can be. Turns out that that advice even applies years later.
Through social media donor support groups, I recently was stunned and outraged to learn that some donors have been told that they have stage 3 chronic kidney disease. One donor said she cried all night. Before you conclude that their “disease” is a result of kidney donation, I hasten to add that these were people with normal kidney function. In other words, as researchers have demonstrated, those living donors DO NOT HAVE CHRONIC KIDNEY DISEASE! Their slightly low readings are perfectly normal for them.
Apparently, their primary care providers—and, unbelievably, sometimes even nephrologists—were referring to the eGFR (estimated glomerular filtration rate) scale based on people with two kidneys and/or real kidney disease. Donors lose 25 to 35% of their pre-donation kidney function, but that’s still sufficient to lead a healthy normal life. It’s meaningless and patently wrong to look at the numbers in a vacuum and say that these people have chronic kidney disease.
As we get older, no matter how many kidneys we have, our kidney function declines. It’s especially common for people over 70, like me, to have a slightly low eGFR. At my last check-up, though, 13 years after donating my kidney to my son, my eGFR was 69 (normal is over 60).
So, if you are a kidney donor, don’t be alarmed at news of a slightly high eGFR. Ask questions (how long has it been in that range? what’s your creatinine?), and always remind your provider that you have one kidney. You may well be relieved to know that your new normal is just fine!