Obesity linked to kidney stone risk

New research cautions that obesity, mild or severe, almost doubles the chances of developing kidney stones.

Findings of the study suggest that the condition could be exceptionally painful, and may require surgery.

Obesity is a medical condition in which body fat accumulates to the extent that could cause increased health problems, and reduce life expectancy.

Those with a body mass index [a number, derived by using height and weight measurements, that gives a general indication of whether or not weight falls within a healthy range.] (BMI) -ratio of weight to height- of 30 and above are considered obese. A score between 25 to 30 is overweight while 18 to 25 is considered normal.

Details of the study

To reach this conclusion, a research team from the Johns Hopkins University School of Medicine analyzed a national database of 95,598 people who had completed a "health risk assessment" form when buying insurance with information about their BMI.

The researchers then tracked the participants for five years from 2002 to 2006, to see whether they develop kidney stone disease or not.

Outcome of the study

On analysis, it was found that around one in 40 people, or 2.9 percent of the non-obese individuals had developed painful kidney stones.

Further, around one in 20 participants, or 4.9 percent of the mildly obese individuals were also diagnosed with kidney stones.

The researchers, however, could not ascertain why mild obesity contributes to kidney stone development.

But they hypothesized that a combination of metabolic factors, and certain types of foods consumed such as high intake of salt in diet, may trigger kidney stone disease even in the mildly obese.

Past connection

Previous studies have also shown a strong association between high body mass index and kidney stone disease.

However, the present study shows that risk of developing the painful urological condition is same for all obese individuals, whether mild or morbidly obese.

"The common thinking was that as weight rises, kidney stone risk rises as well, but our study refutes that. Whether someone is mildly obese or morbidly obese, the risk for getting kidney stones is the same,” study leader Brian R. Matlaga, assistant professor of urology, Johns Hopkins University School of Medicine said.

The researchers have outlined the need for more research to confirm the findings, published in the Feb. 26 issue of the Journal of Urology.

Kidney stone: causes and symptoms

Kidney stones are crystals formed from salts, or minerals that separate from the urine within the urinary tract.