Beck L H
Division of General Internal Medicine, Georgetown University Medical Center, Washington, DC 20007, USA.
Clin Geriatr Med. 1998 May;14(2):199-209.
Despite losing 20%-25% of their original kidney volume, older individuals maintain body fluid hemostasis under most circumstances; however, their ability to withstand environmental, disease-related, or iatrogenic stresses becomes progressively narrowed. Glomerular filtration rates fall with each decade, accompanied by limitations on sodium conservation, potassium ion secretion, and acid excretion. Medications used by older patients are a common cause of hyperkalemia through a number of pathophysiologic mechanisms. In addition, water homeostasis frequently fails due to defects in thirst, urinary concentrating ability, and free water excretion, resulting in hypernatremia or hyponatremia in many sick older patients.
尽管老年人的肾脏原始体积减少了20% - 25%，但在大多数情况下他们仍能维持体液平衡；然而，他们抵御环境、疾病相关或医源性应激的能力却逐渐变窄。肾小球滤过率每十年下降，同时伴有钠潴留、钾离子分泌和酸排泄受限。老年患者使用的药物通过多种病理生理机制是高钾血症的常见原因。此外，由于口渴、尿液浓缩能力和自由水排泄方面的缺陷，水稳态常常失衡，导致许多患病老年人出现高钠血症或低钠血症。
