Dear Dr. Roach: I just had my yearly physical exam and am concerned about my kidney test results. Last October, my GFR was 38; in February, 43. My most recent is 39. I have seen a kidney specialist and a kidney nutritionist, and thought I was eating correctly. I am mystified as to why my GFR went down. I drink 2 liters of water per day and rarely any other liquids, other than a glass of wine or two a month. I am eating vegan (no meat, fish, fowl or dairy) about 98 percent of the time. I do consume vegan cheese and mayo on my daily large salad. I also eat lots of tofu and fruit. I eat no beans (except soybeans), nuts or seeds, as recommended by my kidney specialist. I was a vegetarian for 28 years before becoming nearly vegan last year. I eat two eggs once every week or two. What else can you suggest I do to change my diet so that my GFR improves? At this time, I don’t plan on doing dialysis or a transplant, so when my kidneys are done, so am I. I am currently 75 years young. — L.G.

Answer: While I can understand that you see a drop from February until now, your GFR (glomerular filtration rate, the basic number for kidney function) is actually improved from last year.

These numbers often bounce up and down a little bit, depending on fluid status at the time you took the test (including whether you were fasting). Three points isn’t enough to make a determination of whether the GFR is really decreasing; however, your values are on the low side, even for your age.

As far as diet, changing animal protein to plant protein does seem to slow the loss of kidney function (some loss is inevitable with age). Two liters of water is sufficient for all but the most active adults. If you take medications, the doses should be evaluated to be sure they are right for you: Some may need to be decreased.

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