Kidney Performance (Low GFR for age)

One byproduct of all the blood testing I’ve been doing is that I’ve come to really worry about my kidney health. My eGFR has fallen from 90 to 75 over the last 6 years. The level did increase back to 85 in Dec after 3 months on Rapamycin, but back to 80 now. I have no protein on urinalysis.

I am 42, 165lbs, in normal health, and taking a statin for aggressive prevention. BP averages 118/72 with daily testing. Good glucose control with CGM. I had serious rhabdo when I was 21, and I wonder if this is the fallout from that. I also have high Homocysteine which I’ve not been able to control with vitamins.

This is the Peter Attia episode that scared me: How Peter thinks about managing GFR & high blood pressure in his patients - Peter Attia

I immediately looked at my GFR, saw it had been a low of 75, and now worry about it.

  1. Am I right to be concerned? My GP says this is in the normal range, and stopped worrying. This type of attitude is always challenging for those of us focused on longevity, because we are not trying to just be “normal”.

  2. Does anyone know anything else to do to improve or stabilize GFR? I have periodically taken Canagaflozin 100mg as needed during times of diet challenges. Is kidney health really just a one-way street?

  3. Any other blood or urine tests to watch?

42 yrs old, statins, CGM, high homocysteine…definitely some moving parts.

From everything I’ve been able to read on kidney (grafts, transplants), markers are improved on Sirolimus intervention. My n=1 markers have improved.

Do you have other kidney function tests trending data?

When you say high Homocysteine, how high, and any trending data?

I am homozygous MTHFR C677T (23andme), so at risk for high HCY, but was only 8 pre-interventions. I was able to lower it < 5 following this protocol:

Here’s a study on some trending data for eGFR and when to consider looking deeper, as in perhaps your doc should refer to a nephrologist.

A drop of 90 to 75 over 6 yrs, would, according to paper below (> 10 ml/min in 5 yrs), suggest a referral, although they do say eGFR can be noisy intra-person, and this criteria is not necessarily accepted by clinicians.

What’s your diet like, and has your doc suggested any changes?


Thanks so much.

My Homocysteine started at 17.4 umol/L in October, when I started the regimen you recommended. Last week ist was 13.4.

Thanks for the paper.

My diet is decent, I try to do fairly low carbs, but my salt intake could be lower.

17.4, yes that is high, but you’ve dropped a decent amount.

Are you ongoing/tweaking that HCY stack to try and lower further?

You might have some wonky genes, might need further “precision medicine” pathway analysis.

Elevated HCY is not good, hopefully you can find a way to crush it.

“decent diet” is not good enough, must be awesome!


The reference you shared included trimethylglycine, which I had not seen before. Any brand you recommend? I worry about the random Amazon approach to Vitamins.

This is the supplement I have been taking:

Taking 2 per day is what has gotten me down to 13.4.

I also have read about adding Glutathione. Any opinion?

On diet, one challenge is that a “Kidney friendly” diet is not as friendly to metabolic health, so it’s hard to find the right balance.

My main challenge is finding a doctor who cares enough to really help me on these details, because I am not the common patient, since I look great, and my health seems excellent (until you dig a little deeper).

I was considering becoming a patient of Peter Attia’s but when I heard back from the practice that it is $155K/yr, I thought better of it.

Any thoughts on finding the right docs?

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Yes, a good doc is hard to find. They are mostly in-the-box thinkers toeing the line of med school and AMA thinking. I am always surprised at how little doctors know about supplements of any kind. Prescription medications are all that they preach. I have a reasonably knowledgeable doctor for my basic needs. If I want to know more about my health I have to schedule my own tests.
I am still looking for a more holistic doctor in my neighborhood.

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Yes TMG is indeed used successfully for hacking HCY. I don’t take it, but have read many people who have with great results. At an HCY of 17.4, you have some hacking to do.

On your supplement, it shows (2 of them):

30mg B6
4,000 mcg 6S-5-methylfolate
1,000 mcg B12 Methylcobalmin

I take:

50mg P-5-P B6
6,000 mcg B12 Methylcobalmin
1,000 mcg L-Methylfolate

I don’t think you’ve applied a proper enough hack to your HCY. I’ve followed some people who know their HCY science, the type of specific type of vitamins I take I would give a try.

Nothing to add on Glutathione…my doc has been trying to get me to raise mine, but no luck so far, choosing other mountains to climb.

I fired by “family doctor”, he didn’t care about digging/preventing. I switched to a preventative Functional Medicine Doctor.

Here’s one link to get you started:

SGLT2 inhibitors like Canagaflozin may help preserve kidney function in the long-term, but can result in transient reductions of GFR after starting the medication.

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Have you checked cystatin C? This seems to be a more reliable indicator of renal function IMO because it’s not affected by common diet/lifestyle factors which can make creatinine go all over the place (resistance training, creatine supplementationamd a bunch of other things). Cystatin C is much more stable, and the results should also include a “new” estimated GFR based on the cystatin C result.


Great. I’ll add that to the mix on my next panel.

I see a remarkable difference between eGFR from Creatinine and Cystatin C. 85 vs. 122.

Has anyone else seen such a big delta?

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Yes, I have as well. Both strenuous exercise and creatine monohydrate supplementation can raise creatinine, which in turn can artificially lower eGFR. Cystatin C bypasses all of that. I’m not sure why cystatin C hasn’t become the default standard. I think on one of Attia’s podcasts he says he gets both measurements and takes them both into account when assessing renal function.

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