Decreased renal function among adults with a history of nephrolithiasis: a study of NHANES III.

BACKGROUND Although intuitively appealing, the hypothesis that nephrolithiasis is associated with decreased renal function has not thoroughly been investigated. Because the prevalence of nephrolithiasis and chronic renal disease in westernized societies has risen over the past three decades, we sought to determine if persons with a history of kidney stones have lower renal function relative to nonstone formers. METHODS We used data from the Third National Health and Nutrition Examination Survey (NHANES III) to compare estimated glomerular filtration rate (GFR) between persons over age 30 with and without a history of kidney stones. In total, 876 persons with a history of stones, and 14,129 persons without stones were available for analysis. RESULTS We observed that the association between history of stones and estimated GFR depends on body mass index (BMI) (P= 0.004). After adjustment for potential confounding factors, mean estimated GFR in stone formers with a BMI >/=27 kg/m(2) was 3.4 mL/min/1.73 m(2) lower than that of similar nonstone formers (95% CI -5.8, -1.1) (P= 0.005). No difference was found among persons with a BMI <27 kg/m(2). The probability of an overweight stone former having an estimated GFR between 30 and 59 mL/min/1.73 m(2) relative to a GFR above 90 mL/min/1.73 m(2) was nearly twice that of a similar nonstone former [relative risk ratio (RRR) = 1.87, 95% CI 1.06, 3.30]. CONCLUSION Among overweight persons, nephrolithiasis may not merely be a disease of stones, but may also reduce kidney function. Further work in alternate study samples is needed to validate this finding and determine the mechanisms responsible.