Maalouf Naim M.
Professor of Medicine, Department of Internal Medicine and Charles and Jane Pak Center for Mineral Metabolism and Clinical Research, University of Texas Southwestern Medical Center.
Kidney stones are concretions of different mineral salts mixed with an organic matrix that form in the upper urinary tract. As a stone moves from the kidney to the ureter, it can present with renal colic symptoms and may cause urinary tract obstruction and/or infection. In fact, acute passage of a kidney stone is one of the leading reasons for visits to an emergency room. Over the past four decades, the lifetime prevalence of nephrolithiasis has more than doubled in the United States (and several other developed countries), afflicting around 11% of men and 7% of women. Unless the underlying etiology of stone formation is adequately addressed, kidney stones can recur at a rate of around 50% ten years after initial presentation. The evaluation of a kidney stone former requires an extensive medical history (to identify environmental, metabolic, and/or genetic factors contributing to stone formation), imaging studies to evaluate and track stone burden, and laboratory studies (serum and urinary chemistries, stone composition analysis) to guide lifestyle and pharmacological therapy. The majority of kidney stones are composed of calcium (calcium oxalate and/or calcium phosphate), either pure or in combination with uric acid. Calcium oxalate stones can be caused by hypercalciuria, hyperoxaluria, hyperuricosuria, hypocitraturia, and/or low urine volume. Calcium phosphate stones occur in patients with hypercalciuria, hypocitraturia, an elevated urine pH, and/or low urine volume. In addition to lifestyle changes (increasing fluid intake, reduction in salt intake, moderation of calcium and animal protein intake), pharmacological therapy directed at the underlying metabolic abnormality (thiazides for hypercalciuria, potassium citrate for hypocitraturia, xanthine oxidase inhibitors for hyperuricosuria) can significantly reduce calcium stone recurrence rate. Pure uric acid stones account for 8-10% of all stones, although their prevalence is significantly greater in stone formers with type 2 diabetes and/or the metabolic syndrome. Uric acid stones are primarily caused by an excessively acidic urine, and urinary alkalinization with medications such as potassium citrate can dissolve uric acid stones and prevent recurrent uric acid nephrolithiasis. Cystine stones result from inactivating mutations in genes that encode renal tubular transporters that reabsorb the amino acid cysteine, typically present in childhood, are highly recurrent, and require aggressive control of cystinuria with specific pharmacological therapy. Infection (struvite) stones often present as staghorn and require careful surgical removal of all of the stone material. For complete coverage of all related areas of Endocrinology, please visit our on-line FREE web-text, WWW.ENDOTEXT.ORG.
肾结石是由不同矿物质盐与有机基质混合形成的凝结物，在上尿路中形成。当结石从肾脏移动到输尿管时，可能会出现肾绞痛症状，并可能导致尿路梗阻和/或感染。事实上，肾结石的急性发作是急诊室就诊的主要原因之一。在过去的四十年里，美国（以及几个发达国家）肾结石的终生患病率增加了一倍多，约11%的男性和7%的女性受其影响。除非结石形成的潜在病因得到充分解决，否则肾结石在初次出现后的十年内复发率约为50%。对肾结石患者的评估需要详细的病史（以确定导致结石形成的环境、代谢和/或遗传因素）、影像学检查以评估和跟踪结石负荷，以及实验室检查（血清和尿液化学分析、结石成分分析）以指导生活方式和药物治疗。大多数肾结石由钙（草酸钙和/或磷酸钙）组成，可为纯钙结石或与尿酸混合。草酸钙结石可由高钙尿症、高草酸尿症、高尿酸尿症、低枸橼酸尿症和/或低尿量引起。磷酸钙结石发生在高钙尿症、低枸橼酸尿症、尿液pH值升高和/或低尿量的患者中。除了改变生活方式（增加液体摄入量、减少盐摄入量、适度摄入钙和动物蛋白）外，针对潜在代谢异常的药物治疗（噻嗪类药物治疗高钙尿症、枸橼酸钾治疗低枸橼酸尿症、黄嘌呤氧化酶抑制剂治疗高尿酸尿症）可显著降低钙结石的复发率。纯尿酸结石占所有结石的8-10%，尽管在2型糖尿病和/或代谢综合征患者中其患病率明显更高。尿酸结石主要由尿液过度酸性引起，使用枸橼酸钾等药物碱化尿液可溶解尿酸结石并预防复发性尿酸肾结石。胱氨酸结石是由编码肾小管转运蛋白的基因突变失活导致的，这些转运蛋白可重吸收氨基酸胱氨酸，通常在儿童期出现，复发率高，需要用特定的药物治疗积极控制胱氨酸尿症。感染性（鸟粪石）结石常呈鹿角状，需要仔细手术清除所有结石物质。如需全面涵盖内分泌学的所有相关领域，请访问我们的免费在线网络文本，网址为WWW.ENDOTEXT.ORG。
