Urology Unit, Manzoni Hospital, Via dell'Eremo 9/11, 23900, Lecco, Italy.
IRCCS Ca' Granda Ospedale Maggiore Policlinico-University of Milan, Milan, Italy.
Urolithiasis. 2018 Apr;46(2):167-172. doi: 10.1007/s00240-017-0965-2. Epub 2017 Feb 28.
The aim of this study was to compare the clinical characteristics of "pure" uric acid renal stone formers (UA-RSFs) with that of mixed uric acid/calcium oxalate stone formers (UC-RSFs) and to identify which urinary and dietary risk factors predispose to their formation. A total of 136 UA-RSFs and 115 UC-RSFs were extracted from our database of renal stone formers. A control group of 60 subjects without history of renal stones was considered for comparison. Data from serum chemistries, 24-h urine collections and 24-h dietary recalls were considered. UA-RSFs had a significantly (p = 0.001) higher body mass index (26.3 ± 3.6 kg/m) than UC-RSFs, whereas body mass index of UA-RSFs was higher but not significantly than in controls (24.6 ± 4.7) (p = 0.108). The mean urinary pH was significantly lower in UA-RSFs (5.57 ± 0.58) and UC-RSFs (5.71 ± 0.56) compared with controls (5.83 ± 0.29) (p = 0.007). No difference of daily urinary uric acid excretion was observed in the three groups (p = 0.902). Daily urinary calcium excretion was significantly (p = 0.018) higher in UC-RSFs (224 ± 149 mg/day) than UA-RSFs (179 ± 115) whereas no significant difference was observed with controls (181 ± 89). UA-RSFs tend to have a lower uric acid fractional excretion (0.083 ± 0.045% vs 0.107+/-0.165; p = 0.120) and had significantly higher serum uric acid (5.33 ± 1.66 vs 4.78 ± 1.44 mg/dl; p = 0.007) than UC-RSFs. The mean energy, carbohydrate and vitamin C intakes were higher in UA-SFs (1987 ± 683 kcal, 272 ± 91 g, 112 ± 72 mg) and UC-SFs (1836 ± 74 kcal, 265 ± 117, 140 ± 118) with respect to controls (1474 ± 601, 188 ± 84, 76 ± 53) (p = 0.000). UA-RSFs should be differentiated from UC-RSFs as they present lower urinary pH, lower uric acid fractional excretion and higher serum uric acid. On the contrary, patients with UC-RSFs show urinary risk factors more similar to those for calcium oxalate stones. The dietary approach in patients forming uric acid stones should be reconsidered with more attention to the quantity and quality of carbohydrate intake.
本研究旨在比较“纯”尿酸盐肾结石形成者（UA-RSFs）与混合尿酸/草酸钙结石形成者（UC-RSFs）的临床特征，并确定哪些尿和饮食风险因素易导致其形成。从肾结石形成者的数据库中提取了 136 名 UA-RSFs 和 115 名 UC-RSFs。考虑了 60 名无肾结石史的对照者进行比较。考虑了血清化学、24 小时尿液收集和 24 小时饮食记录的数据。UA-RSFs 的体重指数（BMI）明显（p = 0.001）高于 UC-RSFs（26.3 ± 3.6 kg/m），而 UA-RSFs 的 BMI 虽高于对照组，但无统计学意义（24.6 ± 4.7）（p = 0.108）。UA-RSFs（5.57 ± 0.58）和 UC-RSFs（5.71 ± 0.56）的平均尿 pH 值明显低于对照组（5.83 ± 0.29）（p = 0.007）。三组间每日尿尿酸排泄量无差异（p = 0.902）。UC-RSFs（224 ± 149 mg/天）的尿钙排泄量明显（p = 0.018）高于 UA-RSFs（179 ± 115），而与对照组无显著差异（181 ± 89）。UA-RSFs 的尿酸分数排泄率（0.083 ± 0.045% 比 0.107+/-0.165%；p = 0.120）较低，血清尿酸（5.33 ± 1.66 比 4.78 ± 1.44 mg/dl；p = 0.007）较高。UA-SFs 和 UC-SFs 的能量、碳水化合物和维生素 C 摄入量均高于对照组（UA-SFs：1987 ± 683 kcal、272 ± 91 g、112 ± 72 mg；UC-SFs：1836 ± 74 kcal、265 ± 117 g、140 ± 118 mg）（p = 0.000）。UA-RSFs 应与 UC-RSFs 区分开来，因为它们的尿 pH 值较低，尿酸分数排泄率较低，血清尿酸较高。相反，UC-RSFs 患者的尿风险因素与草酸钙结石更相似。形成尿酸结石的患者的饮食方法应重新考虑，更多地关注碳水化合物的摄入量和质量。
