Water and Fasting Effect on Blood Test eGFR
Posted , 5 users are following.
Had an interesting experience this past week regarding my blood work. For those who do not know I am 68, had one kidney removed on July 31st. Male. Immediately after operation my egfr was 35 for a while. then went to 38, 39 range. Then this past Friday I had blood work done by my kidney doctor. She had me drinking 70 ounces or more of water every day for a month before this test. Well my egfr from the blood test increased to 43, my all time high since the operation. Then the following Tuesday my primary care doctor wanted to check my Cholesterol level and for this blood test I fasted for about 13 hours. Well my egfr went back to 38. On the non fasting blood work my Creatinine was 1.62. On the fasting blood work, just 3-4 days later it was 1.8. Such an effect simply from water consumption. Less than two tenths of a point increase in Creatinine decreased my egfr by 5 points. Both of these doctors are NOT fans of the egfr methodology as it does not take into account the uniqueness of height and weight, nor the reason you are CKD (is it because you only have one kidney, or is it really kidney failure, do you have diabetes or other influencing factors), but it is the only test currently available and "normally" used.
0 likes, 11 replies
marj01201 rick39522
Posted
Marj
stephen_25073 rick39522
Posted
A similar thing happened to me before I had my transplant. Before the transplant and when I was on dialysis doctors tended to dwell on the egfr reading and discounting the fact my creatinine levels read around 1200!! Immediately after my transplant the doctors paid particular attention to my creatinine levels and advised different doctors have different ways of measuring kidney function. My level of efgr during dialysis was as low as 2 and now sits around 48. My creatinine read around 1200 and now sits at 130. For a person with one functioning kidney transplanted this is good.
Stevie
rick39522 stephen_25073
Posted
Interesting Stephen. Here the doctors measure our creatinine differently. Normal for a person with both functioning kidneys is between .7 and 1.3. For a person with a solitary kidney 1.7 to 1.9 is "normal". Mine remains in this range and this is what I pay attention to mostly. It is amazing that just movement from .7 to .8 can make a huge different in the egfr number. My kidney doctor too says we watch the creatinine level. Seems more and more doctors seem to have little faith in egfr.
marj01201 rick39522
Posted
Marj
fran32391 rick39522
Posted
Anyone can "fudge" their numbers by drinking a lot of water before testing. So it sounds right that if you fast for the tests your numbers will go up.
rick39522
Posted
Actually drinking water , as my kidney doctor explains to me, is not "fudging" the numbers. The fudging is NOT drinking. With one kidney it needs all the help it can get to function as best it can. This requires that I drink 64 to 70 ounces of water per day. This will be my life as long as I live. The resultant blood work, urine test is not cheating the system. The numbers are actually how the kidney is functioning. Yes it functions with good numbers because of the water, but this is not different than for example taking medicine for an irregular heartbeat. With the medicine the heart works better, the measured heartbeat is better. Without the medicine for 12 or 24 hours, it will not beat properly. So in the case of my kidney, the water is my medicine. She further supported this by showing how all tests with the "medicine" (water) have shown a constant improvement month to month, because it causes the "internals" of the kidney to actually expand be able to handle more workload. It actually makes your kidney permanently enlarge. But the big benefit of drinking the water is not just the kidney and the numbers. It is flushing out the creatinine and other toxins from the body, that normally would just remain. The GFR went down not because the kidney failed any more, but because there was not enough fluids in the system to wash out the creatinine. My interest and surprise was just how 12 hours without water could make such a difference but also how screwed up the entire gfr thing is. A very slight tenth of a number increase in creatinine, caused a 10% drop in GFR.
marj01201 rick39522
Posted
Rick, this is a great explanation! I have heard the same from my nephrologist. I notice many who participate in this forum, although not all, have been told to drink lots of water for their kidneys. I suppose the major exception to that would be people whose kidneys aren't working well enough to clear fluid; they have trouble retaining fluids so may need to adhere to fluid restrictions.
The bottom line, we each need to do what our nephrologists tell us to do--our treatment plans are all individual.
But what wonderful improvement in renal function for you!! You must be thrilled🐶
Marj
rick39522 marj01201
Posted
Thanks Marj. I am so glad that I had the two tests, with and without fasting, so close together. Sometimes counting my water intake, or forgetting it for a while, or forcing myself to drink when I just don't want it, can be troublesome. But now I see clearly the benefits and it makes me even more aware and I no longer view the consumption as something negative. Yes too you are right that it is not for all. We watched closely if I was retaining any of the increase fluid. Measuring my feet and ankles. Monitoring my weight daily to be sure not abnormal increase. Some can not handle it. Fortunately my heart handles it will in conjunction with the kidney.
Dialysis57 rick39522
Posted
I have to agree. A detailed medical history and whether or not your on any form of medications would be interesting to I would not be too concerned with your blood work, it just gives your nephrologist an indication of how your kidneys are functioning! My mothers "usual" was 1200! So you have a long way to go yet before you start to worry. So set your mind at ease, trust in your Dr and if not happy, seek a second opinion.. Ensure you see them monthly or at the very least, second monthly. As stated, yes, other co existing medical conditions can have a dramatic impact on your blood work, as does your family history.
Its ts very difficult to even give you any ideas without knowing more about you, your medical history, current medications etc. But definitely seek another opinion if you feel your not being listened to, as we all know what our own body's normal to abnormal!
Good luck, and keep us posted!
Regards, Dialysis57
mari11869 rick39522
Posted
I was hospitalized for a twisted small intestine. You cannot eat or drink for 3 days with an NG tube into your stomach to drain the sludge. My creatinine in 3-4 days ranged from 1.1 to 1.4. GFR from 45 to 37 and this was within a few days. My Nephrologist said these levels go up and down, sometimes the lab is not so accurate. I have kidney cysts (many) and he told me it will change from time to time, don't worry about it. He said I could have 30 healthy years left if I took care of myself. I don't worry anymore. I have no symptoms. The kidney cysts showed up on the CT scan. I knew I had CKD but did not know why before the CT scan. I'm 60 yrs. old, 134 lbs., good BP, and I'm super active, walking, swimming living a normal life. It's not worth it to get all tangled up in the minutia of blood work. Kidneys are amazing and I plan to take care of mine by eating right, drinking enough and keeping active.
rick39522 mari11869
Posted
This was great info, great to read, and even made me feel better about myself. Thanks. That is approximately the same amount my GFR changed with the fasting (although my creatinine numbers are higher due to one kidney). We were also similar with the cysts. On my remaining kidney I have a very, very large cyst. It grows continuously. In the last six months is has grown 1/4 inch in each direction. My urologist and my oncologist tell me ignore it. If it gets large enough (grapefruit size) it may start some pain and we will deal with it then. It can not be removed because it would reduce function of the kidney and with only one, that's not good. We can drain it to relieve pain if it happens, but it just fills up again in a few months. So they all say, live your normal life. No one knows what tomorrow will bring. The cancer from the other kidney may be secretly growing in my body someplace else, this kidney may fail, or as my cancer doctor says "or you may be hit by a bus", so who knows. There is also the possibility we can live a normal life. I'm like you and make the best of each day. I'm 68, 175lbs, very good BP (in fact they are going to reduce my medications as it is too low) and I walk 3 to 4 miles daily.