Department of Medicine, Section of Nephrology, University of Chicago, Chicago, Illinois.
Brady Urological Institute, Johns Hopkins University, Baltimore, Maryland.
Clin J Am Soc Nephrol. 2020 Aug 7;15(8):1166-1173. doi: 10.2215/CJN.12671019. Epub 2020 Jun 19.
Incidence of kidney stone disease is rising. It is not known whether mechanisms of stone formation differ across racial groups. Our objective was to identify differing lithogenic risk factors across racial groups in idiopathic nephrolithiasis.
DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: We conducted a retrospective cohort study evaluating metabolic risk factors in black and age-matched white idiopathic stone formers at our tertiary referral center. We compared serum and urine metabolic risk factors pre- and post-treatment across racial groups using analysis of covariance. Generalized linear modeling was used to build regression models for risk of stone formation in both groups.
Among 117 black and 172 white stone formers, urine volume was lower in black stone formers (1.4±0.8 versus 2.0±0.8 L/d, <0.001). Urine calcium was lower in black stone formers (116±70 versus 217±115 mg/d, <0.001). Supersaturations for calcium oxalate were similar among the groups, whereas calcium phosphate supersaturation was higher in white stone formers, and uric acid supersaturation was higher in black stone formers. Electrolyte free water clearance was significantly lower in black stone formers (207±780 versus 435±759 ml/d, =0.02). In the subgroup of 77 black patients and 107 white patients with post-treatment evaluations, urine volume rose significantly and similarly in both groups. Urine sodium was unchanged in whites but increased in blacks by 40 mmol/d (95% confidence interval, 32 to 48 mmol/d). Electrolyte free water clearance remained lower in black stone formers (385±891 versus 706±893 ml/d, =0.02). Post-treatment supersaturations were similar across the groups except for calcium phosphate, which improved with treatment in whites.
Black stone formers have lower 24-hour urine calcium excretion and urine volume. Increases in urine volume with treatment were associated with increased solute, but not free water, excretion in black stone formers.
肾结石疾病的发病率正在上升。目前尚不清楚结石形成的机制是否因种族群体而异。我们的目的是确定特发性肾结石患者中不同种族群体之间的不同成石风险因素。
设计、设置、参与者和测量：我们在我们的三级转诊中心进行了一项回顾性队列研究，评估了黑人和年龄匹配的白人特发性结石形成者的代谢风险因素。我们使用协方差分析比较了种族间治疗前后的血清和尿液代谢风险因素。使用广义线性模型为两组的结石形成风险建立回归模型。
在 117 名黑人结石形成者和 172 名白人结石形成者中，黑人结石形成者的尿量较低（1.4±0.8 与 2.0±0.8 L/d，<0.001）。黑人结石形成者的尿钙较低（116±70 与 217±115 mg/d，<0.001）。两组之间的草酸钙过饱和度相似，而磷酸钙过饱和度在白人中较高，尿酸过饱和度在黑人中较高。黑人结石形成者的电解质自由水清除率显著较低（207±780 与 435±759 ml/d，=0.02）。在有治疗后评估的 77 名黑人患者和 107 名白人患者的亚组中，两组的尿量均显著增加且相似。白人的尿钠无变化，但黑人增加了 40 mmol/d（95%置信区间，32 至 48 mmol/d）。电解质自由水清除率在黑人结石形成者中仍较低（385±891 与 706±893 ml/d，=0.02）。治疗后各组的过饱和度相似，但磷酸钙除外，其在白人中得到改善。
黑人结石形成者的 24 小时尿钙排泄和尿量较低。治疗后尿量增加与溶质但不是游离水的排泄增加有关，在黑人结石形成者中。
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