Jamison R L, Oliver R E
Am J Med. 1982 Feb;72(2):308-22. doi: 10.1016/0002-9343(82)90823-3.
A new approach to the classification of disorders of urinary concentration and dilution is recommended based on recent studies of how the kidney elaborates a urine of widely varying osmolality. The capacity to concentrate urine depends on ft, the fractional reabsorption of solute delivered to the loop of Henle; fu, the excretion of solute relative to the sum of solute excretion and solute delivery to Henle's loop; fw, the fraction of solute loss by vascular outflow from the medulla relative to that reabsorbed by the loop; and finally, collecting duct response to antidiuretic hormone (ADH). A decrease in ft or in increased fu or fw will diminish urinary concentrating ability, as will resistance of the tubule to ADH. Conversely, urinary dilution depends on the delivery of sodium and water to the ascending limb; NaCl reabsorption by the ascending limb; and the absence of ADH. A decrease in sodium and water delivery to the ascending limb or in NaCl reabsorption by the ascending limb will impair urinary diluting ability, as will the presence of ADH. The consequences of disorders in urinary concentrating and diluting ability vary widely. In an alert patient with an intact thirst center, there may be no consequence; in a patient unable to communicate thirst or whose thirst center is deranged, the results may be catastrophic. Keeping in mind the kidney's few basic requirements for formation of concentrated or dilute urine may help the physician avoid these potentially serious dislocations of water balance.
基于最近有关肾脏如何产生渗透压差异很大的尿液的研究，推荐一种对尿液浓缩和稀释障碍进行分类的新方法。尿液浓缩能力取决于ft，即输送到髓袢的溶质的分数重吸收；fu，即相对于溶质排泄和输送到髓袢的溶质总和的溶质排泄；fw，即髓质血管流出导致的溶质损失相对于髓袢重吸收的溶质损失的分数；最后还取决于集合管对抗利尿激素（ADH）的反应。ft降低、fu增加或fw增加以及肾小管对ADH的抵抗都会降低尿液浓缩能力。相反，尿液稀释取决于钠和水输送到升支、升支对NaCl的重吸收以及ADH的缺乏。输送到升支的钠和水减少或升支对NaCl的重吸收减少以及ADH的存在都会损害尿液稀释能力。尿液浓缩和稀释能力障碍的后果差异很大。对于警觉且口渴中枢完整的患者，可能没有后果；对于无法表达口渴或口渴中枢紊乱的患者，结果可能是灾难性的。牢记肾脏形成浓缩或稀释尿液的几个基本要求，可能有助于医生避免这些潜在的严重水平衡紊乱。
