Urinating in cold weather - more or less ?

[Cat_Jones]

Two questions really.

#1 Do we need to pee more in cold weather (or do we just think we need to) ?

#2 If we do pee more in cold weather what is the biological explanation ?

Is it that the body is under more stress in cold weather ? Is it that our metabolism is working faster to generate more heat ?

Many thanks - a colleague of mine needs to know to get one up on some of her students who work for a pharmacetical company. Thanks.

[Finagle]

Sheer speculation, but two things to consider:

a. In cold weather, we’re not losing moisture to perspiration to any notable degree.

b. People will drink lots of hot, caffeinated beverages in cold weather.
Both of these could lead to an increased frequency of urination.

[Chimpy]

We urinate more during cold weather, this is because we perspire less water in sweat trying to cool the body. The reason for this is ADH, or Anti-diuretic hormone; secreted by the anterior pituitary gland. The hypothalamus is a part of the brain responsible for homeostasis (keeping the body’s state the same) if it senses there is too little water in the blood, it will release ADH which means the loop of Henlé in the kidneys reabsorbs more water back into the bloodstream, meaning less is released in urination. In cold weather there is an excess or enough water in the bloodstream, meaning that the pituitary gland releases little or no ADH, this means less water is reabsorbed and so more is released in urination.

[Xema]

Another factor is that as you get cold your body seeks to restrict blood flow to the extremities, to limit heat loss. One aspect of this is reduction in blood volume, accomplished by loss of water from the blood through the kidneys.

[Quercus]

To make Xema’s point a little more clear:

When your body starts getting cold (goes from warm to cold), it temporarily gets rid of some water through urination (as X— explained, it’s a side effect of reducing blood in the extremities). So you may notice the connection between getting cold and having to pee.
But a) this is a one-time thing; you won’t keep peeing more if you stay out in the cold, and b)when your body gets warm again, you’ll need that water back, so you’ll balance it out by peeing a little less as you warm back up (assuming you’re drinking the same amount of liquid the whole time).

[Cat_Jones]

Thanks guys that all makes sense.

[elfkin477]

@Chimpy

We urinate more during cold weather, this is because we perspire less water in sweat trying to cool the body. The reason for this is ADH, or Anti-diuretic hormone; secreted by the anterior pituitary gland. The hypothalamus is a part of the brain responsible for homeostasis (keeping the body’s state the same) if it senses there is too little water in the blood, it will release ADH which means the loop of Henlé in the kidneys reabsorbs more water back into the bloodstream, meaning less is released in urination.

Does this explain why you can drink tons more water than usual on a hard (read:sweaty) hike up a mountain side and not have to pee? I’ve noticed that every time I’ve been hiking…

[Valgard]

Halfway related to this, found out from snowcamping that holding it in makes you colder - your body is wasting energy warming up that few cups of liquid. When you wake up at 3am with a full bladder and are trying to balance the discomfort against having to leave your nice warm shelter to go pee, opt for the latter. It makes a noticeable difference.

Some people kept a spare canteen in their snow cave for just that purpose. I don’t know if they then used it as a hot water bottle.

[KarlGauss]

@Xema

Another factor is that as you get cold your body seeks to restrict blood flow to the extremities, to limit heat loss. One aspect of this is reduction in blood volume, accomplished by loss of water from the blood through the kidneys.

@Quercus

To make Xema’s point a little more clear:

When your body starts getting cold (goes from warm to cold), it temporarily gets rid of some water through urination (as X— explained, it’s a side effect of reducing blood in the extremities). So you may notice the connection between getting cold and having to pee.
But a) this is a one-time thing; you won’t keep peeing more if you stay out in the cold, and b)when your body gets warm again, you’ll need that water back, so you’ll balance it out by peeing a little less as you warm back up (assuming you’re drinking the same amount of liquid the whole time).

@Cat Jones

Thanks guys that all makes sense.

Whoa there. It doesn’t make sense to me.

Cold temperature reduces blood flow to the kidneys. This should reduce urine production and also lead to increased salt and water retention (which would also reduce the amount of urine produced).

As has been noted above, the explanation for cold-induced increased urination, is because of suppression of antidiuretic hormone. This is not a “one-time thing” (unless your urine loss resulting from the cold exposure is so great as to re-stimulate your antidiuretic hormone and overcome its cold-induced suppression).

[Cat_Jones]

I think I meant it made sense when I had a quick glance before bed last night .

Not arguing with anyone here but I get the logic of reducing blood flow to the extremities in cold weather but, and forgive me if I’m missing something obvious as I’ve yet to get enough tea into my system this morning, what’s the advantage of reducing blood flow to an internal organ, let’s say the kidney ?