Drinking ice water may have a mild effect on kidney function, but the overall effect is not significant. All objects have the effect of heat expansion and cold contraction, and the same goes for the blood vessels in the body. If you drink more ice water, it will cause the blood vessels to contract, and so will the renal arteries. When the renal arteries are constricted, the blood supply to the kidneys will be reduced, which is called renal underperfusion. If the patient has underlying renal failure, it may lead to a mild aggravation of renal function, but the aggravation will not be too obvious. Because after drinking ice water, the temperature of ice water is not so low after it has been preheated by the gastrointestinal tract and absorbed into the bloodstream, so the effect on the kidneys is relatively small and therefore will not lead to a sharp deterioration in kidney function. However, it is recommended not to drink ice water, because drinking ice water may lead to gastrointestinal disorders, even if it does not affect the kidneys very much.