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Discussion:
blood gfr versus urine gfr
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Another situation that I am and would appreciate advice... asked for a more exact gfr rather that the above 60 that I got cuz not feeling well, did the 24 hour urine collection followed by the blood test. My urine gfr came out 62 my blood gfr 57. My dr said I am fine and don't need to be tested for 3 months. My creatine is 1 or 1.1 and has been going up since March. I am really feeling different. The nephrologist I did an email consult with in May said my kidneys were starting to fail as indicated by the protein and creatine levels. Concerned yet felt I could prove him wrong. The creatinine and protein have increased in the two weeks between the last labs and this urine/blood test. Should I insist on another blood draw to check it against or not? I am so tired of having to fight these drs. I still haven't gotten a referral to a neph either.
Posted on 08/12/12, 05:02 am
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Reply #1 - 08/12/12  7:31pm
" It's perfectly normal for your numbers to fluctuature a bit from hour to hour and day to day; it happens to all of us. Our serum creatinine is highest at approx 7 am and lowest at approx 7 pm, so getting your labs done at a the same time of day if possible helps to maintain a stable baseline (and always have them check your BP both sitting and standing and in the same arm...or ideally in both arms, again for that baseline).

I have a graph of all my labs since I was first diagnosed with PKD back in 1988 and if I were to have panicked every time something changed (positive or negative) I'd have long since been declared insane! The changes (and the ones you describe are truly minute even though they don't feel like they are) are a perfectly normal part of life and will happen to everyone, even those who don't have kidney disease. Hydration status, what time of day you had the labs drawn, what you ate (or didn't eat) the day(s) before, even an extra Vitamin C tablet can make a change in that serum (blood) creatinine number.

What's important is what is happening to you in the long term (years, not months or weeks). That tells the true story of how your kidneys are faring....and even then your kidneys can surprise you and do much, much better than anyone ever predicted they would. It's also vitally important to remember that only about 50% of ADPKD patients end up in renal failure--this is by no means a death sentence.

Now for those tests your doctor ran and why the results numbers are different (and they will ALWAYS be different). Your GFR (glomerular filtration rate) is based on your blood work alone, usually using the MDRD formula (the print out of your lab work should tell you what formula is being used) and tells the story of how well your kidneys are functioning in respect to cleaning your blood. It estimates your height and weight using a different standard for men and women (it doesn't use your actual body mass index). This provides an ESTIMATE of your kidney function, but is ONLY an estimate.

Your creatinine clearance (the result of the 24-hour urine collection and your serum creatinine (which should have been tested at the same basic time as you did the 24-hour collection), is also an ESTIMATE of how well your kidneys are working, this time by measuring how well they are clearing creatinine from your blood stream THROUGH the kidneys. In people without a kidney disease, that number should be static; everyone clears a certain amount of creatinine through their kidneys based on BOTH muscle mass and protein intake. The formula used accounts for men and women differently, but doesn't consider your actual height and weight, just an average, and has long since been a big debunked by the British scientists as being very susceptible to the effects of eating cooked meat before and during the test (making the resulting number higher than the kidney function actually is...unless the amount of cooked meat consumed is your normal diet). The resulting creatinine clearance also provides an ESTIMATE of kidney function. However, this test isn't considered the most accurate of the kidney function tests because it requires collection of 100% of all urine (every single drop) during the exact 24 hour collection period (nearly impossible for anyone to do) and is susceptible to the effects of diet (both immediately before and during the test....eat more protein, excrete more creatinine, get a higher number). Most of the nephrologists I've had over the years no longer use this test because it's so difficult to get exact results.

I suspect the next time you get labs done, your creatinine will be back down to 1.0, especially if you are well hydrated (which we should all be, drinking 3 liters of fluid per day unless there is a fluid restriction in effect).

As for your desire to see a nephrologist, I most assuredly understand that, but right now, as long as your blood pressure is under control (120/80), there really isn't much a nephrologist can do for you that your primary care doctor isn't doing already. The standard creatinine level to refer a patient to a nephrologist is 1.5 for women and 2.0 for men. Yes, you may be able to see one earlier, but your insurance may not pay. And right now there's still no treatment and no cure...and your primary care doctor has done the email/telephone consult with the nephrologist already.

Instead of focusing on numbers, try focusing on what you can do to get and stay healthy. I know I'm coming in late on the conversation, but if you smoke, stop. If you drink, do so in moderation (if at all; alcohol is very hard on the liver and most medications are processed through the liver, including our BP medications). Focus on a healthy diet, plenty of fresh fruits and vegetables, whole grains, legumes, etc. and LOTS of fresh water!

At the age of 55 or 56, your numbers truly are excellent. There is an age factor in all the GFR and creatinine clearance formulas and you lose "credit" based solely on age alone, even with perfect kidneys.

What is most implortant to remember is that we are a system of systems and not everything that happens to us or that makes us ill is caused by our kidneys or PKD. So if you are feeling ill, talk with your doctor and get checked out--we are so much more than just a set of kidneys!

I hope this helps!
Gentle hugs,
Ruth

PS I think you can safely prove your doctor wrong. At 55 and with a GFR of 62, your kidneys are a long way from failing!! "
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Reply #2 - 08/13/12  3:21am
" It helped tremendously, thank you. I am a little confused though. Should I ask for the bloodtest to be repeated sooner than 3 months? "
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Reply #3 - 08/13/12  10:28am
" Hi TryintoB,

With a creatinine of 1.1 you do not need to have bloodwork done any sooner unless there is something else going on as well (like anemia). My nephrologist started seeing me every 6 months when my creatinine reached 2.0 and then every 3 months when it reached 3.0. It took about 12 years for my creatinine to go from 1.1 to 4.0 at which point I was ready to go forward with transplant. Everybody is different and nobody can predict exactly how long it will take or if you will ever go into kidney failure. My sister has PKD and her creatinine has remained steady at about 2.0 for over 5 years. If you are not feeling well, it could be because of something unrelated to PKD or it could be because the cysts themselves are causing discomfort. It is also wise to keep a close eye on blood pressure and hemoglobin.

Unfortunately there isn't much that a nephrologist can do at this point. From a numbers standpoint you are still very far away from kidney failure. Doctors can try and predict how long it will take but in reality they simply do not know. I would focus on a healthy diet, drinking lots of water and getting plenty of exercise! Once again, I can't state enough how important blood pressure is in this equation.

All the best to you! "
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Reply #4 - 08/13/12  3:01pm
" You have no idea how reassuring this info is. The neph said my kidneys would fail fast - 3-6 months which is why I have been preparing for the worst. This is light on a dark situation. I just need accurate information. By hemoglobin do you mean HGB? "
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Reply #5 - 08/13/12  7:15pm
" OMG tryintoB...I can't imagine why they gave you that prognosis! I know that sometimes PKD can progress rapidly, but I have never heard of someone going from a gfr of about 60 to below 20 in such a short time unless there was a reason for acute renal failure. I understand that you were given a drug that accellerated your cyst growth. It is possible that might figure into the equation but at this point I would recommend either seeking a 2nd opinion from a promary care physician or demanding to see a nephrologist. Normally I would never think to see a nephrologist with such good kidney function but if a doctor has told you to expect your kidneys to fail in such a short perioid of time you have good reason to see a nephrologist--if only to confirm that your PCP is nuts!!

For reference, my creatinine currently fluctuates from .9 to 1.0--this is considered a terrific number to have and I have no worries about my kidney function. Most people would not begin dialysis until they have a gfr of below 12...sometimes as low as 5 or 6. You can get listed for transplant at a GFR of 20 but most physicians would recommend waiting to transplant until the GFR is a bit lower, depending on how the patient feels.

Yes, I think HBG is hemoglobin. If you have a copy of your labs you can see what is "in range" and what is out of normal.

I think what you really need is a doctor who knows a bit more about PKD and kidney disease in general because form the sound of it, yours either doesn't know what he is talking about or is not explaining it to you very well.

Take Care!!! "
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Reply #6 - 08/15/12  9:39pm
" That is even better news for me. Thanks.
I will work on the 2nd opinion. "
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Reply #7 - 08/16/12  7:59am
" There's a newer and more accurate way to test GFR, and so I've supplied this link to help explain it. Also, they don't just gauge kidney function by a few tests alone; rather it's several, and judging whether there is a downward trend or decline in total kidney function; of course they always take into consideration age and other health factors. A healthy person of 20 will have a better GFR than a healthy person of 60! http://labtestsonline.org/understan... "
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Reply #8 - 08/16/12  8:35am
" I am so glad you got more details about your numbers. Many of us here would be thrilled to have those numbers! At that number I would imagine you should not "feel" anything different than usual (except being so stressed out can cause headaches, nausea etc.). Your numbers really are, great! So stop worrying, but get yourself educated! It is your responsibility to know everything you can about this, so you'll know what is going on. i think we all have the labs that are wildly freaky every once in a while. If that happens, don't panic, just ask to have them repeated. Something as simple as not testing the blood quickly enough can wreak havoc with the results. I had to cancel a Christmas vacation to Europe because my Potassium came back to high. I had it repeated on Christmas eve, STAT and I was just fine. I am really happy for you. You know it is quite possible that you may live your whole life without to many problems (or not), but with your GFR where it is at your age it may be that all you ever need to do is watch and wait. I hope so :-). Now go have a great day. It's an amazing feeling when the docs scare the living daylights out of you and your afraid and then you find out you're relatively ok after all. "
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Reply #9 - 08/17/12  5:37am
" I did just that.. I thought back to the drs to get something for the kidney stones that are moving or get into the beautiful mountain lake and let the water heal me, I went to the lake. I had a wonderful swim, came home took a pill, went and picked up my good friend who just came into town and hd a geat day. The pill wore off so m up but I had a great day! Thanks. "

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