AboutNewell R. Falkinburg, M.D., FACP Expertise I am a board certified nephrologist and emeritus professor of medicine at a major medical school and past Director of Nephrology & Hypertension at a university affiliated hospital. I have expertise in all areas of clinical nephrology, dialysis, transplantation and plasmapheresis.
Experience Professor of medicine
Director of Nephrology
Question QUESTION: Hello, I'm 21 years old, 6'1.5, 180lbs. I'm athletic, so my weight doesn't include a lot of body fat. I workout 3 days a week including weight lifting and cardio. I'm not extremely muscular, but before I worked out I weighed 168lbs. I have no family history of kidney disease.
I went in for a routine blood test recently and everything was normal except my creatinine levels were slightly elevated at 1.3. My doc. was a little concerned and had me come in for another workup after being hydrated, and it came up as 1.4! He didn't seem impressed and I wasn't referred to a neph, he just ran a few more tests:
1. I have done 3 urinalysis, 1 indicated a small trace of protein, and 2 showed no protein.
2. My blood tests have shown the following creatinine levels respectively: 1.3, 1.4, 1.2, (and one more after 1.2 which the doctor said was 'normal' but I didn't get the exact reading.)
My resting blood pressure out of the doctor's office fluctuates from 110 to 130 systolic. (140 at the doctors office because I get nervous.)
I have no other health concerns, however this is very bothersome. I've done extensive research on the internet and elevated creatinine seems to be indicative of kidney disease. And I do understand that exercise and muscular stature can affect those levels, but from what I read that seems to apply to serious bodybuilders not lean muscles, and I made sure not to exercise before the reading that showed 1.4!
There is all of my information regarding my recent health history,
so ultimately I have 2 questions:
1. Even though I have a slightly elevated creatinine, should the fact that I have virtually no protein in my urine offset any concerns about chronic kidney disease?
2. I'm curious to know if I should insist on going to a neph to conduct a 24hr creatinine clearance and other necessary tests, or if I should follow my doctor's advice and accept that I'm a healthy 21 year old athletic guy.
ANSWER: Dear Jack,
First, if there has been a delay in answering this I apologize. I just found it archived in my old mail and it is unfamiliar to me.
Your creatinine is PROBABLY a reflection of your muscle mass but that is only a supposition and needs to be PROVEN by a creatinine clearance measurement which will tell you how much creatinine the kidney actually clears in 24 hours. That represents the filtration function of the kidney and is uninfluenced by muscle mass.
you are incorrect regarding the significance of protein in the urine (proteinuria). Although proteinuria is a major "red flag" for kidney disease there exists a whole host of kidney diseases that manifest low amounts or no proteinuria. They are called interstitial nephropathies. If your creatinine clearance is low then you should be worked up for something like that.
Your primary care doc can order the Cr Cl and if it is low then I'd insist upon a referral to a nephrologist.
A last word on the cr cl. The manner of collection is paramount. Say you collect from 7 am on day #1 to 7am on day #2. At the start of the collection (Day #1 @ 7 am) you urinate into the toilet. That begins the collection. On day #2 @ 7am you urinate into the container and that ends the collection.
Thanks for your question and feel free to follow up. I'd also appreciate a follow up also so I can know what's found.
Sincerely,
Dr. Falkinburg
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QUESTION: Alright I went to my doctor and I'm not sure how to interpret his decision. I told him about my creatinine fluctuations and he seemed unimpressed, this is what happened:
He looked at information on my physical from 2 years ago (2005), before I started working out, when I only weighed about 165lbs. My creatinine was 1.0.
2 Years later (now), after working out for a while, my creatinine has been 1.3, 1.4, and 1.2 respectively with my weight around 178 - 184lbs (from weight lifting/heavy protein diet).
He concluded that my muscle mass and diet is causing the variation because I guess he came to the conclusion that if my kidneys were shot and I went from 1.0 to 1.4 in such a short period of time I would have protein in my urine or show other signs.
He said no more testing is needed and that I should stop being concerned with my kidneys. He said there's no reason to do a creatinine clearance test.
I'm not sure whether to be reassured or not because he didn't do any more tests. Does his conclusion sound reasonable? I desperately want to stop worrying about this and get back to my normal routine. thanks!
ANSWER: dear Jack,
Good to hear from you again.
The bad news is that your doctor is absolutely wrong and you are in dire need of a new doctor!
The good news is that he is probably correct....but only probably. You simply cannot tell without a creatinine clearance...a simple, cheap, easy to perform test that has no risk and that will PROVE that your kidney function is normal. Not to do it is stupid!
Please feel free to share this with him.
Therefore, I strongly recommend that you get referred to a nephrologist of at worst a good internist because your present doctor doesn't know what he is doing.
Sorry to have to bad mouth him this way but you need a real evaluation.
Thanks for the follow up.
Sincerely,
Dr. Falkinburg
---------- FOLLOW-UP ----------
QUESTION: Hello Dr. just keeping you updated on what's going on.
I took your advice and changed doctors, hopefully the next one knows what he's talking about. I also went to my university's medical center and consulted with a doctor there about taking a creatinine clearance test, he said I probably have nothing to worry about but went ahead and scheduled the following tests:
1. urinalysis (with emphasis on microalbumin, I'm assuming that's the particular kind of protein that leaks from damaged kidneys).
2. bloodwork (again)
3. 24 hour clearance which I will commence over the weekend.
Next week I have an appointment to discuss my results, and I'll definitely come to you with any questions/updates.
Thanks for all the help, not many people have the ability to talk directly with a specialist about their concerns.
Take it easy, Jack.
Answer Dear Jack,
Welcome back! I'm gratified that everything seems to be on tract. Please get back to me with the results of your tests. I agree, of course, that there is probably nothing to worry about but, since they're your kidneys, you want to be certain.
Don't forget about the collection technique. One missed specimen can introduce up to a 15-20% error in the calculation. So, if you have to have a bowel movement, urinate in the container FIRST.
