Can Drinking Water Alter Your Blood Test?

[Goofy]

I'm going for my monthly blood test today and I just drank a large amount of water.  Will that alter the results in any way?

[LightLizard]

it shouldn't make a difference, really. i get my bloodwork done monthly and i have to fast for twelve hours before. the nurse always reminds me that i can only have water at that time.

[KICKSTART]

With regards your blood test ..not sure but ...with regards dialysis and kidney failure drinking LARGE amounts of water is a definate NO NO  ..how much did you drink ?  You not on fluid restrictions ??

[Jean]

If I dont drink at least 2 or 3 bottles of water before my bloodwork, my GFR goes down, and my Bun and Creat go up. Gfr only by one point.

[Restorer]

Jean, that could be just altering the numbers without changing your actual kidney function or total waste amounts. If you drink 3 500ml bottles of water, you're adding up to 1.5 liters of water to your body, some of which, for the first few hours at least, will be in your circulatory system. That just dilutes your blood and, yes, it makes your creatinine and urea numbers go down, but it can also make all the other numbers go down. It's only a temporary thing - it's not really helping you, just deceiving the test.

[Slywalker]

I have to drink just so my veins show up!!! 
I'm what they call a "tough" stick and apparently that is in my file as now I get the most experienced with comments about "they know all about me"  Now what does that mean I wonder?

[kamalshah20]

I read somewhere that the human body typically has about 5-6 liters of blood. So, if someone is about 2 liters above their dry weight, I would think that would actually show numbers that are too low because most of the lab values are expressed per unit of volume.

Thanks
Kamal
http://kamaldshah.com

[Jean]

Really, what I meant to say ( Yes, I guess I am a ditzy blonde) is that my Dr. urges me to drink a lot of water before my test. otherwise I show up as dehydrated. I am not on D, does that make a difference.?

[kristina]

Restorer might be right when he says that
drinking a lots of liquid before a blood test
could alter the numbers, but not the function.
I am not on dialysis yet and
I drink every day exactly the same amount of liquid,
evenly proportioned through the day.
When I go out I take thermos flasks
and continue as if I am at home.
I feel that is a kind way for my kidneys
to deal with the situation and
I also feel it gives me a better idea,
of how my kidneys are really working.
Good luck.

[kidneydoc]

Absolutely if you have a very low GFR.

When GFR is low water is not excreted promptly. The result is a dilution of blood electrolyte. Drink enough water and you may enter a state known as water intoxication and have seizures due to low sodium. Before then however the extra water in the circulatory system would accumulate in the lungs causing shortness of breath (difficulty breathing) and ultimately respiratory failure if you continue drinking.

Creatinine levels may appear low due to dilution.

GFR will be lower in a dehydrated patient who has diminished kidney function because the kidney is more susceptible to shocks such as dehydration when you have CKD. Having a normal amount of hydration for each test is a good way to ensure the numbers are consistent for interpretation. So dont run a marathon then do your blood test one time then drink a ton of water and do your blood tests the next. Be consistent so that any changes seen are actually due to the kidney function and nothing else.

Cheers.

[Goofy]

I'm not on dialysis and I don't have any water restrictions.  I have to have water like coffee drinkers need coffee.  If I don't have ice water in the morning, I can get kind of crabby!  I drink water all day long.  I can't eat without drinking water.  My father used to tell me that he was going to get a hose and have it at the dinner table!

My dad was on dialysis and he was on fluid restriction.  I would look at him and say, "I hope I don't have kidney disease because there is no way I could be restricted on fluids.  Now look where I'm at!  You never know what your future holds.