Context Larger body size may result in increased urinary excretion of calcium, oxalate, and uric acid, thereby increasing the risk for calcium-containing kidney stones. It is unclear if obesity increases the risk of stone formation, and it is not known if weight gain influences risk.Objective To determine if weight, weight gain, body mass index (BMI), and waist circumference are associated with kidney stone formation. Design, Setting, and ParticipantsA prospective study of 3 large cohorts: the Health Professionals Follow-up Study (N=45988 men; age range at baseline, 40-75 years), the Nurses' Health Study I (N=93758 older women; age range at baseline, 34-59 years), and the Nurses' Health Study II (N=101877 younger women; age range at baseline, 27-44 years).Main Outcome Measures Incidence of symptomatic kidney stones. ResultsWe documented 4827 incident kidney stones over a combined 46 years of follow-up. After adjusting for age, dietary factors, fluid intake, and thiazide use, the relative risk (RR) for stone formation in men weighing more than 220 lb (100.0 kg) vs men less than 150 lb (68.2 kg) was 1.44 (95% confidence interval [CI], 1.11-1.86; P=.002 for trend). In older and younger women, RRs for these weight categories were 1.89 (95% CI, 1.52-2.36; PϽ.001 for trend) and 1.92 (95% CI, 1.59-2.31; PϽ.001 for trend), respectively. The RR in men who gained more than 35 lb (15.9 kg) since age 21 years vs men whose weight did not change was 1.39 (95% CI, 1.14-1.70; P=.001 for trend). Corresponding RRs for the same categories of weight gain since age 18 years in older and younger women were 1.70 (95% CI, 1.40-2.05; PϽ.001 for trend) and 1.82 (95% CI, 1.50-2.21; PϽ.001 for trend). Body mass index was associated with the risk of kidney stone formation: the RR for men with a BMI of 30 or greater vs those with a BMI of 21 to 22.9 was 1.33 (95% CI, 1.08-1.63; PϽ.001 for trend). Corresponding RRs for the same categories of BMI in older and younger women were 1.90 (95% CI, 1.61-2.25; PϽ.001 for trend) and 2.09 (95% CI, 1.77-2.48; PϽ.001 for trend). Waist circumference was also positively associated with risk in men (P=.002 for trend) and in older and younger women (PϽ.001 for trend for both). ConclusionsObesity and weight gain increase the risk of kidney stone formation. The magnitude of the increased risk may be greater in women than in men.

Abstract. Diet plays an important role in the pathogenesis of kidney stones. Because the metabolism of many dietary factors, such as calcium, may change with age, the relation between diet and kidney stones may be different in older adults. Uncertainty also remains about the association between many dietary factors, such as vitamin C, magnesium, and animal protein, and the risk of kidney stone formation. To examine the association between dietary factors and the risk of incident, symptomatic kidney stones in men and to determine whether these associations vary with age, a prospective cohort study was conducted of 45,619 men without a history of nephrolithiasis. Self-administered food frequency questionnaires were used to assess diet every 4 yr. A total of 1473 incident symptomatic kidney stones were documented during 477,700 person-years of follow-up. For men aged Ͻ60 yr, the multivariate relative risk (RR) for stone formation in the highest quintile of dietary calcium as compared with the lowest quintile was 0.69 (95% confidence interval [CI], 0.56 to 0.87; P ϭ 0.01 for trend). By contrast, there was no association between dietary calcium and stone formation in men aged 60 yr or older. The multivariate RR for men who consumed 1000 mg or greater of vitamin C per day compared with those who consumed less than the recommended dietary allowance of 90 mg/d was 1.41 (95% CI, 1.11 to 1.80; P ϭ 0.01 for trend). Other dietary factors showed the following multivariate RR among men in the highest quintile of intake compared with those in the lowest: magnesium, 0.71 (95% CI, 0.56 to 0.89; P ϭ 0.01 for trend); potassium, 0.54 (95% CI, 0.42 to 0.68; P Ͻ 0.001 for trend); and fluid, 0.71 (95% CI, 0.59 to 0.85; P Ͻ 0.001 for trend). Animal protein was associated with risk only in men with a body mass index Ͻ25 kg/m 2 (RR, 1.38; 95% CI, 1.05 to 1.81; P ϭ 0.03 for trend). Sodium, phosphorus, sucrose, phytate, vitamin B 6 , vitamin D, and supplemental calcium were not independently associated with risk. In conclusion, the association between calcium intake and kidney stone formation varies with age. Magnesium intake decreases and total vitamin C intake seems to increase the risk of symptomatic nephrolithiasis. Because age and body size affect the relation between diet and kidney stones, dietary recommendations for stone prevention should be tailored to the individual patient.Diet plays an important role in the pathogenesis of kidney stones (1), but little is known about the effect of aging on the association between specific dietary factors and nephrolithiasis. In the past, prospective studies that evaluated dietary influences on kidney stone formation included only small numbers of older participants. The first observational studies to demonstrate an inverse association between dietary calcium and incident kidney stones analyzed stone formers who as a group were predominately younger than 60 yr (2,3). The mean age of subjects in the controlled, randomized trial that supported the results of these studies was 45 yr (4).The relati...

DM is a risk factor for the development of kidney stones. Additional studies are needed to determine if the increased risk of DM in stone formers is due to subclinical insulin resistance.

Summary-It is unclear whether optimal levels of 25-hydroxyvitamin D (25(OH)D) in whites are the same as in minorities. In adult participants of NHANES, the relationships between 25(OH)D, bone mineral density (BMD), and parathyroid hormone (PTH) differed in blacks as compared to whites and Mexican-Americans, suggesting that optimal 25(OH)D levels for bone and mineral metabolism may differ by race.Introduction-Blacks and Hispanics have lower 25-hydroxyvitamin D concentrations than whites. However, it is unclear whether 25(OH)D levels considered "optimal" for bone and mineral metabolism in whites are the same as those in minority populations.

Abstract-Numerous 5 and various locations in the kidney. 6 -9 Experimental studies demonstrate that 1,25(OH) 2 D inhibits renin expression, 4,10 enhances insulin secretion and sensitivity, 11,12 and blocks proliferation of VSMCs. 13 Although cross-sectional studies demonstrate that 25(OH)D levels, and skin exposure to UVB radiation (the major source of vitamin D), 14,15 are associated with lower blood pressure, 16 -22 prospective data are limited. An interventional study conducted in 148 vitamin D-deficient elderly women demonstrated a 9% decrease in systolic blood pressure with supplemental vitamin D and calcium compared with calcium alone. 23 In a previous prospective study of older women (first Nurses' Health Study) and men (Health Professionals Follow-up Study), we demonstrated an association between deficient levels of 25(OH)D and risk of incident hypertension after adjusting for age, race, body mass index (BMI), and physical activity. However, that study had limited statistical power (190 incident cases), 24 and we did not measure plasma parathyroid hormone (PTH), calcium, or creatinine, factors that are associated with 25(OH)D and that may influence the risk of hypertension. [25][26][27][28] To determine the independent association between plasma 25(OH)D levels and risk of incident hypertension, we conducted a prospective nested case-control study of 1484 young, healthy women from the second Nurses' Health Study. Methods Study PopulationThe Nurses' Health Study 2 is an ongoing prospective cohort study of 116 671 female registered nurses that began in 1989. Participants are followed via biennial questionnaires that gather information on health-related behaviors and medical events. Follow-up of participants was Ͼ90% through 2005. During the years 1997 to 1999, 29 616 participants contributed blood samples that were stored in liquid nitrogen (Ϫ130°C). We conducted a nested case-control study of incident hypertension among those women who contributed blood samples and who did not have prevalent hypertension at the time of blood collection. The institutional review board at Brigham and Women's Hospital reviewed and approved this study.We selected cases and controls from among those who met the following criteria at the time of blood collection: (1) fasting for Ն8 hours; (2) no diagnosis of hypertension; (3) no use of antihypertensive medications; (4) no diagnosis of cancer (except nonmelanoma skin cancer); (5) no diagnosis of either coronary heart disease or diabetes; and (6) BMI Ͻ30 kg/m 2 . This last eligibility criterion is important, because high BMI is a powerful predictor of hypertension 29,30 and of 25(OH)D levels. 22,31 Using risk-set sampling, we selected 750 cases who subsequently developed hypertension and 750 controls who did not develop hypertension. Controls were matched to cases on the following

SummaryBackground and objectives Not all fluids may be equally beneficial for reducing the risk of kidney stones. In particular, it is not clear whether sugar and artificially sweetened soda increase the risk.Design, setting, participants, & measurements We prospectively analyzed the association between intake of several types of beverages and incidence of kidney stones in three large ongoing cohort studies. Information on consumption of beverages and development of kidney stones was collected by validated questionnaires.Results The analysis involved 194,095 participants; over a median follow-up of more than 8 years, 4462 incident cases occurred. There was a 23% higher risk of developing kidney stones in the highest category of consumption of sugar-sweetened cola compared with the lowest category (P for trend=0.02) and a 33% higher risk of developing kidney stones for sugar-sweetened noncola (P for trend=0.003); there was a marginally significant higher risk of developing kidney stones for artificially sweetened noncola (P for trend=0.05). Also, there was an 18% higher risk for punch (P for trend=0.04) and lower risks of 26% for caffeinated coffee (P for trend,0.001), 16% for decaffeinated coffee (P for trend=0.01), 11% for tea (P for trend=0.02), 31%-33% for wine (P for trend,0.005), 41% for beer (P for trend,0.001), and 12% for orange juice (P for trend=0.004).Conclusions Consumption of sugar-sweetened soda and punch is associated with a higher risk of stone formation, whereas consumption of coffee, tea, beer, wine, and orange juice is associated with a lower risk.

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There is uncertainty about the relation between 24-h urinary uric acid excretion and the risk of calcium oxalate nephrolithiasis. In addition, the risk associated with different levels of other urinary factors needs clarification. We performed a cross-sectional study of 24-h urine excretion and the risk of kidney stone formation in 3350 men and women, of whom 2237 had a history of nephrolithiasis. After adjusting for other urinary factors, urinary uric acid had a significant inverse association with stone formation in men, a marginal inverse association with risk in younger women, and no association in older women. The risk of stone formation in men and women significantly rose with increasing urine calcium and oxalate, and significantly decreased with increasing citrate and urine volume, with the change in risk beginning below the traditional normal thresholds. Other urinary factors were also associated with risk, but this varied by age and gender. Our study does not support the prevailing belief that higher urine uric acid excretion increases the risk for calcium oxalate stone formation. In addition, the current definitions of normal levels for urinary factors need to be re-evaluated.