POTASSIUM-RICH FRUITS VERSUS POTASSIUM-POOR CITRUS PRODUCTS IN STONE RISK

该子项目是利用NIH/NCRR资助的中心赠款提供的资源的许多研究子项目之一。子项目和研究者（PI）可能从另一个NIH来源获得了主要资金，因此可以在其他CRISP条目中表示。所列机构为中心，不一定是研究者所在机构。柠檬酸钾的管理，现在被认为是一种有效的治疗复发性尿石症。在安慰剂对照试验中，它已被证明可降低特发性低柠檬酸尿性钙肾结石患者的结石形成率高达72%。其他研究表明，柠檬酸钾治疗可以有效降低低柠檬酸尿、高尿酸尿以及噻嗪类药物无反应患者的结石形成率。柠檬酸钾的作用被认为是通过其柠檬酸尿和碱化作用发挥的。钾和柠檬酸盐几乎完全被胃肠道吸收。柠檬酸盐在体内几乎完全氧化，但吸收的钾不会代谢。因此，产生“阳离子过量”，产生碱负荷。碱负荷通过减少肾小管对柠檬酸盐的重吸收来增强尿柠檬酸盐排泄。一小部分吸收的柠檬酸盐在体内逃脱氧化并经尿液排泄，导致柠檬酸钾的柠檬酸尿作用。 本研究的目的是比较正常人和结石形成者在控制代谢条件下，富钾柑橘类水果产品（橙子汁）和贫钾产品（柠檬水）的尿碱化和柠檬酸尿效应。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Administration of potassium citrate is now considered an effective treatment for recurrent urolithiasis. It has been shown to decrease stone formation rate in patients with idiopathic hypocitraturic calcium nephrolithiasis by as much as 72% in a placebo-controlled trial. Other studies have demonstrated that potassium citrate therapy can effectively reduce the rate of stone formation in hypocitraturic, hyperuricosuric, as well as in thiazide-unresponsive patients. The effect of potassium citrate is believed to be exerted through its citraturic and alkalinizing actions. Both potassium and citrate are nearly completely absorbed from the gastrointestinal tract. Citrate is nearly completely oxidized in vivo, but absorbed potassium is not metabolized. Thus, a "cation excess" is created, producing an alkali load. The alkali load enhances urinary citrate excretion by reducing renal tubular reabsorption of citrate. A small fraction of the absorbed citrate escapes oxidation in vivo and is excreted in the urine, contributing to the citraturic action of potassium citrate. The object of this study is to compare the urinary alkalinizing and citraturic effects of potassium-rich citrus fruit product (orange juice) with those of potassium-poor product (lemonade) under controlled metabolic conditions in both normal subjects and stone former.s