The following environmental factors may affect your risk for kidney stones.
Your level of activity influences your risk for stones. The more active you are, the more you are likely to perspire. While exercise is an excellent way to maintain or reach your goal body weight, improve cardiovascular function and increase muscle and bone mass, it may also lead to dehydration and overly concentrated urine if you do not replace fluids. The more you sweat, the more fluids you should drink.
If you are very inactive, you may be losing bone strength, which could result in loss of calcium from bone. That calcium is filtered by the kidneys and a large amount of calcium may not be able to be reabsorbed. Instead, excessive calcium gets excreted in the urine, where it can lead to stone formation.
If you work in high temperatures, such as in hot weather or in certain types of manufacturing or processing where high temperatures are the norm, you may be predisposed to dehydration and concentrated urine.
Alternatively, if your work situation does not offer you the freedom to go to the restroom when needed, you may restrict your fluid intake in order to accommodate the lack of facilities or time needed to go to the restroom. This will cause your urine to be concentrated and increase the chance of forming kidney stones.
The many nutritional factors contributing to kidney stones are listed below. For more information about ways to cater your diet to avoid stones, please go to the nutrition therapy section.
- Lack of fluids
- Too much sodium
- Too much meat from beef, pork, poultry, fish, and seafood
- Too little or too much calcium
- Too much oxalate absorbed
- Too few fruits and vegetables
- Too much sugar
Body weight is associated with an increased risk for kidney stones, especially for women. In other words, the more weight we carry, the higher our risk for stones. Body Mass Index (BMI), which is a measure of your weight as related to your height, is a general but useful way to assess whether your body mass is too high. A BMI greater than 25 for most individuals is considered overweight. Waist circumference is also associated with increased risk for stones. The larger your waist size, the more likely you are to form stones.
Men generally have a higher incidence of stone formation. The probable reasons include higher body weight, higher caloric intake, larger portion sizes and intake of meat, fish and poultry, and higher sodium intake.
An increase in stone formation among women in the U.S. has been observed over the last couple of decades. Pregnancy increases the risk for stone formation among women, but the incidence is quite low (one in 1,500 pregnancies).
The risk of stone formation appears to increase with age up to about 50 years. The majority of kidney stones occur in people between 20 and 60 years of age. At about 60 years, the overall incidence of kidney stones slowly declines with age.
Among Americans, Caucasians have the highest incidence of kidney stones, followed by Mexican-Americans. African-Americans have the lowest risk.
In the U.S., the highest incidence of stones occurs in the South and the lowest in the West. The reasons for this are not exactly clear, although the hotter weather in the southern states may lead to dehydration, which may cause urine to become too concentrated.