islandbiker

does anyone know if your kidney numbers in a routine blood test would/could change from simple dehydration? i.e. cr levels up and gfr down - i have never had a problem w/ kidneys but i do get severely dehydrated at times - live in hawaii, sweat a LOT after a 3 or 4 hour daily mountain bike rides.

Blackberry

I don't have an answer for you, but here's a big Aloha. Welcome aboard.

islandbiker

Mahalos for the warm aloha Blackberry!

jppe

I don't think I can answer your question but I have those types of issues. I'm really bad not to drink enough fluids and dehydrate easily........even when not riding.

I went several years with passing kidney stones every 3 months because I was not flushing out the very concentrated fluids in the kidneys enough. I've now got that in check but I can offer that hydrating is extremely important.

The only way I can solve it is to watch the clock while riding and make myself take drinks from my water bottle every 10 mins or 15 mins depending on how hot/humid it is. If I wait until I'm thirsty I've waited way too long.

To show you how bad I am I've done 6-7 hour bike rides and only drank 2-3 bottles of fluids. That's about 1/2 what I should have drank.....

islandbiker

Thankyou - yeah i have been dosing myself w/ water - counting the oz's i drink is definitely helping, it makes me more conscious of hydrating...hot hot hot here & i really have to make an effort. you sound like me - i do know how important it is (i've been riding for 15 years daily) i just forget.....i have to force myself. thanks so much for your input

centexwoody 

Here in central Tx, heat is an incredible impediment to exercising outdoors for many of us. As a kid, I suffered a serious heat stroke (eventually put into a bathtub of ice cubes to lower body temp) and ever since have to watch my participation/activity in hot weather. My physical therapist wife tells me my hypothalomus has been permanently 're-set' due to the heat stroke. My sweat response to exercise or heat is INSTANTANEOUS and for me to re-hydrate means that I drink before, during and after rides. At this time of year I can only ride between 6 - 8 am otherwise the heat makes me sick for hours or even days.

About a decade ago, my backpacking partners & I got lost in an Arizona wilderness for 48 hrs. past when we were to have finished a 5-day hike in rugged backcountry. Search & rescue teams, media helicopters, the whole circus was out looking for us. We hiked out eventually on our own but one partner worried when we left the creekbeds for higher ground that we would run out of water. So he stopped drinking with the thought that when we had emptied our canteens, he would have some to offer us. About three hours before we were found/rescued/made the main trail, he almost fell out because of back pain. We were transferring weight out of his pack into ours and he could barely walk. Turns out his kidneys were starting to shut down from dehydration. That's when we found out he hadn't had anything to drink for over 4 hours in the blazing AZ sun! His doctor later said that the backache was the 1st sign that his hours were numbered...

From that experience I can imagine that kidney tests could reflect dehydration stress but don't know any of the physiological specifics, sorry. (See? I'm trying to return to the original thread topic at the end of my ramblings...)

islandbiker

GRREAT story! and...you really did answer my question, thankyou!

Lion Steve

My wife is a medical lab lechnician. She told me that these three tests are for kidney function.

BUN 5.0 - 20.0 expected range

CREATININE 0.4 - 1.3 expected range

AST 15 - 41 expected range

sch

The answer is yes, but over short term of a bike ride only the BUN is likely to go up. Numbers in the 25 -35 range could occur with short term dehydration such as a 4-8hr bike ride in hot weather even with a lot of oral intake, there is a limit to how much your stomach can deliver to the body ~750ml/hour is a typical estimate whereas sweating, breathing and occasional urination can greatly exceed this. Creatinine takes longer to change and might go up a few tenths. Epic rides like 24 hr, randonneuring events or rides across Death Valley in July might result in more serious changes with muscle breakdown. Watching the Tour recently with several days of riding in 97F makes some of these guys look super human to have as little fall off in performance as they did. Personally I really wilt above 90-92F. One final comment, the elevations of BUN to 25-35 range will reverse in 6-12 hours with rehydration.
Steve

islandbiker

Thankyou - that was a help too. what about gfr? isn't that the most important?? anyway - thanks so much for your response!

islandbiker

that was clearly what i wanted to hear (good news i think) - 30 mile mountain bike ride and then hr + hike in 80-85 degree weather and then blood test pretty immediately after two days of double work outs. never had bad (however slight) numbers before and it was alarming but i think that they are supposed to factor in age to blood tests like that....thankyou so much!