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@hans1671102377 · 23 Jan 2021

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Why do you suddenly need to pee in the cold?

Researchers have spent years pumping ice water into the urinary bladder of rats.
Just before you go out the door, nothing seems to be going on.. But as soon as you are out in the cold for a while, suddenly you feel the signal of a full bladder. Where does this urge come from so suddenly?

There is a medical-scientific name for this phenomenon: cold diuresis. In 1957, American doctors Ernest Bors and Kenneth Blinn described it as a reflex of the bladder to sudden cold. In their little subtle experiments, through a catheter, they ran six milliliters of ice water into the bladder of spinal cord veterans, resulting in strong uncontrolled bladder emptying. Cold stimulates the contraction of the bladder was their conclusion. But under normal conditions, the urine in the bladder, of course, never suddenly becomes so cold, so as an explanation for the cold diuresis, it fails.

After years of being in the weather with ice water pumping into the urinary bladder of rats, Japanese researchers discovered ten years ago that also sudden cooling of the whole body provokes plasma reaction. Rats that were abruptly transferred from 27°C to 4°C reacted by much more frequent urination, while the pressure in their bladder increased. The cold stress also increases heart rate and blood pressure. However, with a second cycle from hot to cold, the plasma response remained out. Others found that even a large cooling of a piece of skin somewhere on the body (hind legs or ears, no matter) with acetone, for example, led to an overactive bladder in laboratory animals. Capillaries in the skin

According to professor of urology Laetitia de Kort of UMC Utrecht, the current state of affairs is that there are two explanations for the phenomenon: “The first is that when you have cold feet, it also affects the bladder because the nerve signals at the bottom of the spinal cord correspond to those of the bladder. This allows you to feel more urge.”

A second explanation is that with cold the capillaries in the skin contract, causing the kidneys to expel fluid and thus the bladder becomes more filled. “In the first case, the high need is more a feeling. In the second case, you really have to pee more.”

Whether these theories understand the phenomenon to its essence, De Kort does not know. “It's not all that hard scientifically researched,” she warns. “It's a bit experimental; what happens when we cool someone's feet strongly with ice? ”

That cold is an incentive for #dewatering is fixed. For example, a recently published (and again Japanese) epidemiological study in the Urology journal shows that the frequency of night urination is clearly related to the temperature of the living room just before going to bed. In particular, in winter, this occurs. Japanese people whose living room temperature was below 12°C at bedtime were significantly more likely to suffer from an overactive bladder than compatriots who sought their beds from a cosy warm living room. Incidentally, the night temperature in the bedroom did not have a major influence, even though it was usually lower than in the living room. The researchers explain that from the insulating effect of blankets.

Urologist De Kort notes that her patients seem to suffer noticeably less from urine loss this winter. Not necessarily because it's warmer she says, “but because people in this age of corona go out less. And at home there is always a toilet nearby.”