ANDY:
I wasnt when I wrote this. JK.
Here's a section pertaining to kidney function from a recent T-Nation.com article.
Kidney Function
It's common dogma among
physicians that high protein diets are bad for your kidneys. Dr. Lowery
here at TMUSCLE has beaten that idea pretty much to death recently.(6)
So I won't get in to too much detail here on that. But the bottom line
is that high protein intake may be harmful to your kidneys, and it may not
be. We have literally no evidence to go on one way or the other. So
your doctor pretty much doesn't have a leg to stand on when he tells
you that you're killing your kidneys.
The notion that protein
is harmful comes from studies of people with damaged kidneys—people
with either chronic renal insufficiency (CRI) or chronic renal failure
(CRF). In these people there's no doubt about it. The higher your
protein intake, the faster your kidney disease is going to worsen.
It
makes sense when you think about it. These are people whose kidneys
can't even keep up with the basic demands their bodies place on them.
Increasing the demand on the kidneys above that basal state can't
possibly be good. But can we extend that principle to people with
normal and healthy kidneys? There's no reason to think we can, and a
lot of reasons to think we can't.
The kidneys are remarkably
robust organs with a lot of excess capacity. In fact, you have to lose
about 75% of the functioning units (nephrons) in your kidneys before we
even see changes in your kidney function tests. And that doesn't even
take into account the fact that the kidney can dramatically increase
its filtration rate from the resting state in a healthy adult.
An analogous situation occurs with the heart. In a healthy adult, HIIT, or any kind of cardio for that matter, is good
for your heart. But take someone with heart failure, or severe coronary
artery disease. It's probably not a good idea for them to start running
stair laps.
Heck, that's why all the ED drugs have
disclaimers to ask your doctor if it's safe for you to have sex. If you
take an already weakened heart and stress it, bad things can happen.
But you don't see doctors recommending healthy people avoid exercise,
do you?
Our next concern regarding kidneys is the blood tests
doctors use to determine how well they're functioning. There are two
numbers in particular we're interested in: Blood Urea Nitrogen (BUN)
and blood creatinine (Cr).
BUN is a waste product of protein
metabolism. Creatinine is a breakdown product from the creatine
phosphate found in your muscles, heart and brain. Doctors normally
check these values with a simple blood test, which tells them the
concentration of each.
Here's where things get tricky—and
where doctors can make wrong assumptions. The concentration of these
substances in your blood is affected by multiple factors, only one of
which is kidney function. BUN concentration changes with your hydration
status (low when you're well-hydrated, high when your dehydrated).
It
also changes in response to how much protein you're digesting and
turning over. The more protein you take in, the higher your BUN is
going to be.
Creatinine on the other hand is a lot more stable.
It's produced at a relatively constant rate; higher or lower depending
on how much muscle you have, due to the constant process of muscle
breakdown and rebuilding.
As such, the concentration in your
blood has a lot to do with how much lean body mass you have. That said,
there are certain things that can make your creatinine spike. Severe
infections or other stressors increase muscle breakdown as a
consequence of the cortisol and inflammatory hormones coursing through
your body. For the same reason, a particularly intense workout or
competition can do the same thing.
There is a 'normal range'
for each of these things. And people with blood levels of BUN and Cr
that are outside of this range often do have kidney problems.
On
the other hand, there are a heck of a lot of weight trainers that end
up seeing abnormal values in their bloodwork, which can set them and
their doctors to freaking out.
But these 'normal' ranges are
based on the assumption that you're 'normal' when it comes to all of
those other factors I just discussed. Higher protein intake means a
higher BUN. Higher lean body mass means a higher blood Cr. Greater
physical stressors (and consequent increase in creatine turnover) means
a higher Cr. Do you think any of these factors apply to T-Men? Darn
right they do.
So your blood test comes back and your renal
function tests indicate a possible problem. The doctor calls you in a
panic, telling you that you've murdered your kidneys with all that
protein and creatine and you need to stop them now. What do you do?
Well,
your doctor's just overextended himself. He actually has no clue how
your kidneys are doing and neither do you. But it's okay, because we do
have the tools to directly calculate how well your kidneys are working,
we just don't use them very often.
But it's going to need a
piss test. One heck of a piss test. Twenty-four hours' worth of pee in
an opaque jug to be exact. You see, the only way to figure out if your
kidneys are filtering waste products well enough is to see how much they're excreting. Seems like common sense, doesn't it?
What
I would do is ask to do a direct creatinine clearance measurement.
You're going to want to hold off on working out for a couple days—which
will drop your creatine down to the basal level from simple muscle
turnover—but I wouldn't stop taking protein and creatine.
After
you've given your system time to clear out any possible stress-related
increase in creatinine production, come back in for another blood test
and to grab the jug. The lab will compare your blood concentration of
Cr to the amount in your urine. This will tell us exactly how well the
kidney is disposing of waste, and allow us to control for all those
ways in which you're 'abnormal'.
Like I said, it could turn out
that your kidneys really are in rough shape. But more than likely it's
just the fact that you get more protein and have more muscle than most.
here's the full article: http://www.t-nation.com/free_online_article/sex_news_sports_funny_grok/what_your_doc_doesnt_know_about_weightlifting
if this doesn't satisfy you, i can find some other articles from the medical journals.
Andrew Berry