Blood test after a workout shows how hydration is super important

I think everyone here understands the importance of hydration throughout the day and before/during/after workouts. I understand that life gets busy and sometimes we forget to drink enough water or use electrolytes in our bottles. However, even mild dehydration can have negative consequences. This became very clear to me earlier this week when I got the results of a recent blood test.

Last week I had blood work done about 1h after finishing a very hard 90 min workout. I had almost 2 full bottles of water with Skratch sports hydration during the 90 min workout. I didn’t drink water much water after, because I was in a hurry to shower, eat, and drive to my appointment. I did however take my multivitamin.

I am sharing the results of my test below. As you can see, the numbers in red are values outside the “normal” range.

All the red numbers (except B12) are related to kidney function. According to my doctor, these are very likely out of range because I was dehydrated after the workout, and he is not concerned about kidney disease. But I will tell you, that result freaked me out and as you can imagine, I did a lot of my own research about these values and how they interact after getting the result. What gave me some comfort was the creatinine level, which is typically also elevated in cases of kidney disease. Still, I am making an appointment with my Urologist (I had kidney stones in the past) and until I clear this I will be worried.

Anyway, it became very clear to me how a mild dehydration can affect so much on the body, and I wanted to share this with you all to encourage you to really pay attention to your fluid intake. I mean, I had almost 2 bottles of Skratch and still…

Now the elevated B12 (that is another Google research nightmare) - that was likely due to the 25,000% of daily value that I took with my multivitamin 1h before the test.

I’ll be back in 3-4 months for another test. Wish me luck.


Thanks for sharing! I’m taking this to heart - as someone with 1 kidney…and need to do better on my water.


Thank you for sharing. It took me a few years but I figured out that I go thru a 24 oz bottle of fluid (Nuun) each 15 miles. It’s harder to do that in the winter but I know I have got to do better. I wonder if that’s enough ? Thank you for the reminder of non bike riding hydration. I was doing great when I was working but after retirement not so much. Good luck with the next round !

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The recommended amount for most people is one bottle per hour

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I had a similar experience with my iron levels in a blood test. I know it’s very difficult not to consult with “Dr. Google” (we all do it) but don’t think about it too much. You will be seeing an expert soon just in case there’s something off but as you mentioned, it will probably be hydration related and nothing more serious so stay calm and drink your water :wink:


When I learned how closely related my migraines were to hydration and electrolytes I then learned how to stay on top of them better. I’d get crazy exercise induced ones and finally (I don’t remember exactly when) learned it was basically self inflicted. I haven’t had one in a long time. And I’d get them weekly. Super important to pay attention to ourselves!


I think hydration is my big weakness. I really don’t feel thirsty until it’s too late and then it’s impossible to quench it… this is embarrassing but I can drink one cup of coffee, eat lunch, and don’t drink until a workout. Like 0. I know there is some liquids in food but thinking I get one cup of coffee, which in itself can de dehydrating, and I go To the bathroom several times a day means I start workouts and races on zwift dehydrated. I don’t really drink a lot during either. But then I am in crisis in the evening, drink a lot and have to get up and pee during the night… vicious cycle. I’ve gotten better. I bought a nice flask that keeps liquid cool. It motivates me to drink at least 1 to 2 bottles during the day

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Post ride I try to grab a fresh bottle of water or something directly off the trainer and walk around with it. It’s then a mindless activity to drink it.
As to vitamins I’ve been using CareOf since I can customize. Since I was an infant I’ve had a mild allergy to iron and usually cannot take supplements. So I’m usually slightly anemic. Multi don’t work, I have a negative reaction to the iron in them. What I’ve found is I can take iron if it’s buffered by calcium and a stand alone supplement. I also take B-12 as mine is a bit low. D due to the latitude and a B complex. Seems to work.

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@medic7404 I’m glad you posted about your migraines. I used to get awful ones when it was super bright & hot outside & I always thought they were related to the heat but never thought about hydration as the root cause. I haven’t really had any this summer & thought it could be attributed to the lack of stress since I retired but maybe I’ve gotten a little better with my hydration. Or maybe it’s both. It really helps to know it’s not just me.

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I’m curious what the next test will show. I’ve also read we only need to take B12 1x week in all the vegetarian groups I’m in.
I can drink all day and then not drink once I return home from work. So the opposite of Siji.
What Elise does anyone drink to remain hydrated? I get tired of water

And to ask about what Stacy Sims says in her book, does drinking all water and no electrolytes hydrate our blood too much? And make it diluted? So we should add some electrolytes to our water, other than when we work out? :woman_shrugging:t2:

That can be the case for some people, but I would not make a blank recommendation that all women over a certain age drink electrolytes outside of the workout window. It is possible to drink too much water and get hyponatremia, but a few things need to be present for that to happen. I think it’s safe to assume that simply drinking several glasses of water a day won’t “dilute” the blood or cause someone to be low on sodium, unless they don’t eat any salt on their diet. But if you drink lots of water and still feel thirsty (and assuming that is not due to an underlying health reason), then it’s a good idea to add some electrolytes in the water- but not for all the water of the day- maybe one bottle/day, and the electrolytes should be the DAILY (not sport) hydration type (lower concentration).

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that makes total ssense. Thanks!

I just got my bloodwork back as well - terrible kidney numbers because I only have 1 kidney and I don’t drink water anymore (I know, I know)…so promptly back to 2 liters a day, starting today (doctors orders) and then will review the test.

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Alright @mapmeister it’s you and me - let’s do this!!!

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@tank35girl and @mapmeister - I too am a migraine sufferer and dehydration due to exercise is a sure fire way to bring one on. I have to add electrolytes (tailwind) to my hydration for exercise. I try to drink 1/4 bottle every 15 minutes or 5 to 6 miles on the bike. So, by 2 hours both bottles should be gone. Whatever is left over after my ride, I finish and I then drink another bottle of tailwind driving home.

@Coach_Theia - in reviewing your bloodwork. I would have the same conclusion as your physician.
Individual results on a blood test mean less than looking at the whole picture.
GFR is a calculation based off your other numbers. I actually hate that they even put this on your lab work results. This is a horrible, gross generalization equation. There are other tests and equations to really show kidney function. This calculation is skewed by age, weight and sex- especially lower weight females.

The quick equation is:
GFR = (140-age)(weight kg)/(72 x creatinine) then multiply that number by 0.85 for females.
Female gender puts you at 85% of male GFR. When I calculate GFR, any one with a normal creatinine, I use as a 1 (otherwise you are falsely elevating or decreasing the number upwards of 30 to 40 percent). If someone is obese, their GFR is falsely elevated. A lower weight person, their number can look falsely low. An “average” adult weighs 70 to 75 kg (so 72kg). The reason I do this is- lower weight people do not have slower working kidneys. There is also a calculation that adjust weight to height ratios.

So, by the Linda B (aka Petals) calculator: if you put in my generalizations for you
Age= 47 years old avg weight= 72 kg (I know you weigh a lot less than that) Creatinine=1
Everything cancels itself out and you get 140-age x 0.85 = 79 ml/min.

If I use your official numbers
Age=47 weight =57 kg creatinine 1.1
GFR= (140-47)x (57kg)/(72 x 1.1) then multiply by 0.85 which will equal = 56 ml/min
holy crap! Did I just nail their calculation or what?. :woman_superhero:

The slightly elevated BUN (urea nitrogen), albumin and potassium with normal creatinine, protein and other electrolytes (Na, CL, CO2, and anion gap) would suggest someone slightly dehydrated. Most Calcium is located in bone, so blood calcium by itself is not something that can be fixed quickly.
Someone over hydrated would see a low sodium, lower potassium.
In Chronic kidney disease creatinine would be elevated like numbers of 2 to 4! Now the GFR calculator starts to give more real life numbers.

For my bloodwork- ( I have autoimmune issues), my Eo%, for eosinophils is 18% :astonished:

This is your medical lesson for the week. If you have any questions, let me know.


Holy :poop: :poop: :poop: @Petals that’s amazing! Dang!! Thank you for that valuable perspective. I didn’t know you were so knowledgeable about this stuff.

I got the results of my kidneys ultrasound and fortunately everything looks normal.

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Anytime. Im happy to put those 30 years of clinical pharmacy good use. I love explaining medical things!


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