Compared with their normal weight peers, young people who are even modestly obese have more than four times the risk for gallbladder disease according to Corinna Koebnick, PhD, of Kaiser Permanente Southern California in Pasadena, and colleagues.
And compared with boys, the adjusted odds ratio for girls also was quadrupled.
Risk factors such as female sex, family history, and obesity have been recognized for gallstones in adults, but because of the former rarity of gallbladder disease in children, little is known about potential contributing factors.
Gallstones form when bile becomes supersaturated with cholesterol, either from increased uptake or synthesis in the liver, as commonly occurs in obesity.
To explore the possible effects of the pediatric obesity epidemic on rates of gallstones in youth, the reserachers examined the electronic health records of more than 500,000 health plan enrollees ages 10 to 20.
Overall, the prevalence of overweight, defined as a body mass index (BMI) between 25 and 30, was 19.6%.
Moderate obesity -- BMI between 30 and 35 -- was seen in 13.7%, and extreme obesity, or BMI of 35 or higher, in 7.7%.
A total of 766 had been diagnosed with gallstones.
The odds ratio in both sexes for overweight was 2.39, and 6.39 for extreme obesity.
Aside from gender, these factors were associated with elevated risks for gallstones:
- Older age
- Hispanic ethnicity
- Low neighborhood education level
Among boys, adjusted odds ratios for those who were overweight, moderately obese, and extremely obese were 1.46, 1.83, and 3.10. But for girls, the corresponding odds ratios rose to 2.73, 5.75, and 7.71.
Girls who were oral contraceptive users also had a doubling of risk. This association was modified by weight, with odds ratios reaching 5.32 when users were overweight, and 15.16 and 11.33 for those who were moderately or extremely obese, respectively.
Biliary cholesterol secreted by the liver also is elevated in the presence of estrogen. In this study, girls exposed to estrogen from oral contraceptives were at notably high risk, although the researchers cautioned that in an observational study such as this, causation cannot be inferred.
The racial differences seen in this study, with Hispanics having a 55% greater risk for gallstones than non-Hispanics, also have been seen in adults, although the highest rates among adult women is for Native Americans, then Hispanics.
"Further longitudinal data are needed to investigate factors contributing to the observed racial and ethnic disparities and to implement strategies to reduce and eliminate such disparities," the researchers wrote.
Limitations of the gallstones obesity study included the reliance on electronic health records for the diagnosis of gallstones and the possibility of some cases being undiagnosed and some oral contraceptive users being unidentified.
The researchers concluded that gallstones should be added to the list of obesity-linked disorders such as dyslipidemia and diabetes that are on the rise among youth.
"Due to the shift towards extreme childhood obesity, especially in minority children, pediatricians can expect to face an increasing number of children affected by gallstone disease, which has previously been limited to adults," they advised.
The lead author received funding from the National Institute of Diabetes and Digestive and Kidney Disorders and Kaiser Permanente Direct Community Benefit funds.
Reference: Koebnick C, et al "Pediatric obesity and gallstone disease: results from a cross-sectional study of over 510,000 youth" J Pediatr Gastroenterol Nutr 2012; DOI:10.1097/MPG.0b013e31824d256f.