My creatinine and Cystatin-C levels move around quite a bit depending on how much I am drinking (which can be a lot) and how much Sodium and Potassium I am supplementing (which can be a lot).
What I think is happening is that the kidneys have a standard function available and prioritise different tasks in various ways. If you increase the amount of Potassium or Sodium to be excreted that takes a priority over creatinine or Cystatin-C processing. (it may for example be a demand on ATP for this in some way). Hence the potential kidney function itself is not changing, but the biomarkers are.
Other biomarkers I look at for kidney function are Urea and Urate. Urate, however, varies a lot anyway.
At the moment I am trying to get an ideal balance between cation supplementation and kidney markers. This is so I can supplement with a high level of citrate, but have good results on the kidney biomarkers.
After an acute kidney injury at age 70, my GFR pegged at 16 for eight or nine months. My nephs told me to prepare myself for dialysis. I told them, “No way. I’d rather die.” But then, quite unexpectedly, my GFR jumped to 24. That was seven years ago. It is now around 40. And I am not unique. .
If the cause of CKD is hypertension, then the progression of the disease will be arrested or reversed in about five percent of cases. Lucky me. Of course, I contributed to my own cause by strictly adhering to the renal diet. I’m now taking SS-31, which I hope will have an even more salubrious effect on the kidneys.
Date of Testing 5/20/24
Age 54
Weight 98.5 pounds
Height 5’1
Creatinine 0.85
eGFR 81 (per lab)
Minimally processed omnivore diet/take creatine most days
No alcohol or tobacco
Rapa 1.5 years
Based on: “Recommendation 3.4.1: We suggest that adults with high BP and CKD be treated with a target systolic blood pressure (SBP) of <120 mm Hg, when tolerated, using standardized office BP measurement (2B).” (see page S212)
120 mm Hg in “office BP” means 115 mm Hg using 24h ABPM (source).
People with an eGFR that normally falls between 60 and 89 that isn’t explained by advanced age may wish to have a uACR test done to screen for early kidney disease. An eGFR in this range in someone who isn’t elderly can be normal, but it’s generally thought of as a gray area or watch zone. So the uACR test can help to screen people in this zone for evidence of early CKD. An ordinary dipstick urinalysis may not be sensitive enough.
I’d encourage everyone to bypass the eGFR (it fluctuates a lot day to day and less useful if you carry more muscle mass) and get their Cystatin C tested instead.
The problem isn’t eGFR per se. The problem is the inaccurate eGFR on the lab report, which is just inversely correlated with serum creatinine.
I had to explain all this to my primary care physician when I bulked up significantly, because she was convinced I was on the verge of kidney failure, and I was like “I did some reading. Please order cystatin C.” Then you can calculate your eGFR yourself using both datapoints. My cystatin-C only eGFR is nearly 2x my creatinine-only eGFR.
eGFR: 94 as of August 2024
age 70
Male
I haven’t started rapamycin yet but would like to soon. I was using compounded rapamycin and had several blood tests, each of which showed rapamycin below measurable levels, so I consider that as “haven’t started yet”. The multiple blood tests were of variations such as putting the compounded rapamycin capsule in other types of capsules including those advertised as acid-resistant, mixing rapamycin with a penetration enhancer and applying to skin, and dissolving under tongue.
My eGFR was not previously that high. I wonder if it’s higher this year because I started taking enzymes or apple cider vinegar.
Diet: no beef or pork. I probably don’t get enough protein.
