Cold diuresis and immersion diurisis

[xristos]

Cold temperatures make the body reduce blood flow to keep warm our vital organs. This increases blood pressure and kidneys try to remedy this by getting rid of some water in the blood causing us to pee. Same happens when diving with vasoconstriction, spleen contraction and gravity?

This is all common knowledge I think.
I don't understand though, after this process we have less blood volume with the same amount of red blood cells and haemoglobin mass or the body destroys the extra cells and hemoglobin to keep its previous blood consistency in lesser volume?
Also, say I had x litres of blood previously will the body fairly quickly return to that value given sufficient mineral stores?
What happens with salt, water and mineral balance? Should I be worried since I'm noticing the symptoms in extreme manner (1.5 liters in 5 hours having drank 200ml since the previous day and woke up to pee).
We us freedivers it's normal to notice this at greater degree?

 

[SDS]

Exposure to cold and breath hold diving induce a blood shift away from the periphery causing the blood to pool centrally.
A similar shift is seen in astronauts: due to microgravity, ~1/5 of the blood normally found in the extremities is now found centrally. Microgravity exposure beyond 3 days causes Hbmass to decrease by 10 to 15%. This is primarily induced by attenuated EPO production, with EPO levels dropping below baseline and therefore signaling for the destruction of young red blood cells in order to restore normal central blood volume.

The difference between freediving and microgravity:
- the mammalian dive reflex is transient, space flights are usually longer.
- breath hold diving also provides a hypoxic stimulus, stimulating rather than inhibiting EPO production
- the loss in plasma volume due to diuresis will be quickly restored upon hydration

If you wonder how much fluid you lost during a dive sessions, measure the difference in body weight before versus after the dive, and add the amount of fluid you ingested between these two measurements to that number. Also take into account the volume you urinated between the two measures. Replenish accordingly (a bit more than what you lost, i.e. drink 1.5 times the kg body weight you lost in liter of water/other drinks).

I bet that great diuresis could be indicative of great mammalian dive reflex? Just make sure to rehydrate wel!
Not sure whether continued diuresis considerable time after diving causing you to pee at night is to be expected... maybe someone else can provide you a better answer to that question..

 

[xristos]

Exposure to cold and breath hold diving induce a blood shift away from the periphery causing the blood to pool centrally.
A similar shift is seen in astronauts: due to microgravity, ~1/5 of the blood normally found in the extremities is now found centrally. Microgravity exposure beyond 3 days causes Hbmass to decrease by 10 to 15%. This is primarily induced by attenuated EPO production, with EPO levels dropping below baseline and therefore signaling for the destruction of young red blood cells in order to restore normal central blood volume.

The difference between freediving and microgravity:
- the mammalian dive reflex is transient, space flights are usually longer.
- breath hold diving also provides a hypoxic stimulus, stimulating rather than inhibiting EPO production
- the loss in plasma volume due to diuresis will be quickly restored upon hydration

If you wonder how much fluid you lost during a dive sessions, measure the difference in body weight before versus after the dive, and add the amount of fluid you ingested between these two measurements to that number. Also take into account the volume you urinated between the two measures. Replenish accordingly (a bit more than what you lost, i.e. drink 1.5 times the kg body weight you lost in liter of water/other drinks).

I bet that great diuresis could be indicative of great mammalian dive reflex? Just make sure to rehydrate wel!
Not sure whether continued diuresis considerable time after diving causing you to pee at night is to be expected... maybe someone else can provide you a better answer to that question..

Maybe I phrased it incorrectly. I didn't pee at night that amount. This volume was calculated from the weight I lost after getting exposed to cold for 5 hours. Didn't drink during that period. And this being morning I tried to clarify that I wasn't overly hydrated because I peed during night and didn't drink more than 200ml from the previous night till the last urination.
For the rest i will comment later, want to comprehend better first.

Thanks a ton for taking time to post. Hope everything is well, you are the very best mate.

 

[SDS]

Oh sorry, I misunderstood that final question a bit
You wanted to ask whether freedivers (with a trained MDR) experience a similar tendency of pronounced cold-induced diuresis (i.e., 1.5 L/5h) ... Can't answer that question (I don't experience it that much, but then again, particulary during winter I can't consider myself 'trained' unfortunately).

 

[xristos]

Just a follow up question, wetting my hands causes diuresis ? because I do notice it quite often. https://www.mentalfloss.com/article/51268/does-hand-warm-water-trick-really-work