Obesity, weight gain increase risk of kidney stone formation
Kidney stone formation is influenced by obesity and weight gain, especially in women, according to a study published in last week's JAMA (2005; 293:455-62).
The study's authors, from Brigham and Women's Hospital in Boston, based their conclusion on a review of three large studies: the Health Professionals Follow-up Study, the Nurses' Health Study I, and Nurses' Health Study II. Among the approximately 245,000 individuals studied, there were 4,827 incidences of kidney stones over a combined 46 years of follow-up. The investigators, who accounted for differences in diet, fluid intake, and medications, discovered the following about body size and kidney stone risk:
- Obese women have a 90% greater risk of kidney stone formation than women in a lower category of body mass index.
- Obese men have a 33% greater risk of kidney stone formation than men in a lower category of BMI.
- Women who gained 35 pounds since the age of 18 years have a 70% greater risk of kidney stones.
- Men who gained 35 pounds since age 21 have a 39% greater risk of kidney stones.
"Our study demonstrated that multiple measures of larger body size, including larger waist circumference, higher weight, and higher body mass index, were related to an elevated risk of kidney stones," said lead author Eric Taylor, MD. "In addition, weight gain over time was associated with an increased risk of stones."