Dehydration and Kidney Stones


Think of your kidneys as your body’s waste processing unit. Several times a day, all the blood in your body cycles through your kidneys to be filtered. This filtering removes waste and helps maintain a healthy balance of water, salt, and minerals in your blood [1]. Usually the salts, minerals, and other waste materials are removed as urine, but some of the filtered-out chemicals can build up and form solid crystals. These are called kidney stones.



Dehydration and Kidney Stones


Not all kidney stones—or nephrolithiasis, to be medically accurate—are the same. They can vary in composition and size, ranging from the size of a grain of sand to the size of a golf ball. It is estimated that around 1.5% of men and up to 1% of women develop this condition at some point in their lives. A number of risk factors are linked to the formation of kidney stones including inherited conditions, diet, and dehydration [2].


Why should you be concerned about kidney stones?


Small kidney stones may pass out in the urine unnoticed. However, when kidney stones become stuck in the kidney or in the tubes urine passes through on its way out of the body (e.g. ureter and urethra), these hard objects can cause serious pain, blood in the urine, or nausea [2]. Imagine trying to swallow a sharp rock—it would be very pleasant as it made its way down the tube of your throat.



Does dehydration cause kidney stones?


kidney stones water


Dehydration—losing more liquid than you’re taking in—increases your risk of developing, or repeatedly developing, kidney stones. This association emerged in scientific studies that looked at why certain occupations increased peoples’ risks of getting kidney stones. A study in 1980 investigated why lifeguards had high rates of kidney stone disease [3]. Of the 11 Israeli lifeguards with kidney stones studied, all had lower than normal daily urine volumes (amongst other risk factors). Low urine volume can be caused by hot climates, high sunlight exposure, intense physical activity, work in hot environments, and low fluid intake, all factors that lead to uncompensated water loss. Numerous subsequent studies with larger populations have shown that low urine volumes/dehydration is linked to increased risk of kidney stones [4].



How to prevent kidney stones


(Spoiler: by keeping hydrated!)


The scientific evidence has lead the NHS (National Health Service) to specify that avoiding dehydration is the best way to prevent kidney stones. Diluting your urine through good hydration can help prevent the formation of kidney stones by decreasing the concentration of stone-forming minerals in your kidneys. Or, the more hydrated you are, the lower the likelihood of buildup of waste products, and the less likely stones will form [5].


kidney stones water


But how do you know if you’re hydrated enough to help prevent kidney stones? It’s simple: check the color of your urine! If you decrease the amount of fluid taken in by eating or drinking, your kidneys will begin to filter less water out of your blood. (Maintaining the proper volume of water in your blood is very important.) Less water filtered out by your kidneys means less water in your urine. The more concentrated your urine is—or, the less water it has— the darker and more yellow it appears. Conversely, the paler it appears, the more hydrated you are. It’s not a perfect test, but checking the color of your pee is a simple way to help prevent kidney stones.

Instead of diligently checking the color of your pee, try to stay regularly hydrated. Adding
Hydrant to a glass of water makes it ridiculously simple to ensure effective hydration.





Writer: Josie Elliott
Editor: Elizabeth Trelstad,




1. WebMD. Picture of the kidneys. WebMD provides information about health and disease. This article is a concise introduction to kidney structure and function.


2. NHS. Kidney stones overview. This page gives an overview of kidney stone symptoms, causes, diagnosis, treatment and prevention, as well as linking to more in-depth pages of each subject.


3. Increased incidence of nephrolithiasis in lifeguards in Israel, Better et al, 1980. This is the original research article that mentions the link between lifeguards with kidney stones and low urine levels.


4. Hydration for health. Water intake and kidney stones - dehydration. This article gives a good overview of the research on the link between dehydration and kidney stones.


5. NHS. Kidney stones, prevention. An in-depth page from the National Health Service on preventing kidney stones.

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