2115 THE IMPACT OF DIETARY CALCIUM AND OXALATE RATIOS ON STONE RISK

Abstract

You have accessJournal of UrologyStone Disease: Evaluation & Medical Management I1 Apr 20122115 THE IMPACT OF DIETARY CALCIUM AND OXALATE RATIOS ON STONE RISK Jessica Lange, Kyle Wood, Patrick Mufarrij, John Knight, Ross Holmes, and Dean Assimos Jessica LangeJessica Lange Winston-Salem, NC More articles by this author , Kyle WoodKyle Wood Winston-Salem, NC More articles by this author , Patrick MufarrijPatrick Mufarrij Winston-Salem, NC More articles by this author , John KnightJohn Knight Winston-Salem, NC More articles by this author , Ross HolmesRoss Holmes Winston-Salem, NC More articles by this author , and Dean AssimosDean Assimos Winston-Salem, NC More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2012.02.2284AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES Dietary calcium and oxalate intake influence the development of calcium oxalate kidney stones. We hypothesize that an imbalance in the amount of calcium and oxalate in meals might impact gastrointestinal oxalate absorption and urinary oxalate excretion. This imbalance may promote hyperoxaluria when oxalate intake is high and calcium intake is low, leading to an elevated risk of stone formation. METHODS A diet-controlled study was conducted with ten healthy, non-stone forming adults (8 females, 2 males, mean age 30.8 ± 3.3 years, mean BMI 22.5 ± 2.8 kg/m2) placed on controlled diets with daily calcium and oxalate contents of 1000 mg and 750 mg, respectively. Patients consumed a balanced calcium/oxalate ratio diet for one week, observed a one week washout period, and then consumed an imbalanced calcium/oxalate ratio diet for one week. The balanced diet contained 333 mg of calcium and 250 mg of oxalate at each meal, while the imbalanced diet contained 400 mg of calcium and 20 mg of oxalate at breakfast and lunch and 200 mg of calcium and 710 mg of oxalate at dinner. Urine specimens were collected on the last four days of each diet phase and were subdivided into four collection periods. Outcome measures included urinary creatinine, calcium, and oxalate as well as Tiselius index, an estimate of urinary supersaturation with calcium oxalate. Differences in urinary parameters were analyzed using two-way repeated measures analysis of variance (ANOVA) and t-tests. RESULTS Total daily calcium excretion, oxalate excretion, and Tiselius index were similar between the balanced and imbalanced diet phases. Two-way repeated measures ANOVA of subdivided measurements revealed a decrease in calcium excretion over time, an increase in oxalate excretion over time, and an increase in Tiselius index over time for both groups. T tests revealed significant differences in calcium excretion between the balanced and imbalanced diet phases in the 1-6 p.m. (83.11 vs 110.21, p<0.04), 6-11 p.m. (71.27 vs 107.16, p<0.02), and 11 p.m.–8 a.m. collections (55.00 vs 41.79, p<0.02). There was significantly higher oxalate excretion in the balanced phase in the 1-6 p.m. time period (28.06 vs 16.74, p<0.01). CONCLUSIONS Regardless of the dietary calcium-to-oxalate ratio, urinary supersaturation is increased in the evening, and the balance or imbalance of calcium and oxalate intake at mealtime has limited impact on estimated stone risk. The focus for patients, therefore, should be on maintenance of a normal total daily dietary calcium intake as well as increased fluid consumption in the evening hours, especially if increased amounts of oxalate are consumed. © 2012 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 187Issue 4SApril 2012Page: e854 Advertisement Copyright & Permissions© 2012 by American Urological Association Education and Research, Inc.MetricsAuthor Information Jessica Lange Winston-Salem, NC More articles by this author Kyle Wood Winston-Salem, NC More articles by this author Patrick Mufarrij Winston-Salem, NC More articles by this author John Knight Winston-Salem, NC More articles by this author Ross Holmes Winston-Salem, NC More articles by this author Dean Assimos Winston-Salem, NC More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...