University of Colorado School of Medicine, 12700 East 19th Avenue C281, Aurora, CO 80045, USA.
Nat Rev Nephrol. 2013 Jan;9(1):37-50. doi: 10.1038/nrneph.2012.246. Epub 2012 Nov 20.
Hyponatraemia--the most common serum electrolyte disorder--has also emerged as an important marker of the severity and prognosis of important diseases such as heart failure and cirrhosis. Acute hyponatraemia can cause severe encephalopathy, but the rapid correction of chronic hyponatraemia can also profoundly impair brain function and even cause death. With the expanding elderly population and the increased prevalence of hyponatraemia in this segment of society, prospective studies are needed to examine whether correcting hyponatraemia in the elderly will diminish cognitive impairment, improve balance and reduce the incidence of falls and fractures. Given that polypharmacy is also common in the elderly population, the various medications that may stimulate arginine vasopressin release and/or enhance the hormone's action to increase water absorption must also be taken into consideration. Whether hyponatraemia in a patient with cancer is merely a marker of poor prognosis or whether its presence may alter the patient's quality of life remains to be examined. In any case, hyponatraemia can no longer be considered as just a biochemical bystander in the ill patient. A systematic diagnostic approach is necessary to determine the specific aetiology of a patient's hyponatraemia. Therapy must then be dictated not only by recognized reversible causes such as advanced hypothyroidism, adrenal insufficiency, diuretics or other medicines, but also by whether the hyponatraemia occurred acutely or chronically. Information is emerging that the vast majority of cases of hyponatraemia are caused by the nonosmotic release of arginine vasopressin. Now that vasopressin V2-receptor blockers are available, a new era of clinical investigation is necessary to examine whether hyponatraemia is just a marker of severe disease or whether correction of hyponatraemia could improve a patient's quality of life. Such an approach must involve prospective randomized studies in different groups of patients with hyponatraemia, including those with advanced heart failure, those with cirrhosis, patients with cancer, and the elderly.
低钠血症——最常见的血清电解质紊乱——也已成为心力衰竭和肝硬化等重要疾病严重程度和预后的重要标志物。急性低钠血症可导致严重脑病，但慢性低钠血症的快速纠正也会严重损害脑功能，甚至导致死亡。随着老年人口的扩大以及该人群中低钠血症的患病率增加，需要进行前瞻性研究，以检验纠正老年人低钠血症是否会减少认知障碍、改善平衡并降低跌倒和骨折的发生率。鉴于老年人中也普遍存在多种药物治疗，还必须考虑到可能刺激精氨酸血管加压素释放和/或增强激素作用以增加水分吸收的各种药物。癌症患者的低钠血症是否仅仅是预后不良的标志物，或者其存在是否会改变患者的生活质量，仍有待检验。在任何情况下，低钠血症都不能再被视为患病患者的生化旁观者。有必要采用系统的诊断方法来确定患者低钠血症的具体病因。然后，必须根据公认的可逆病因（如严重甲状腺功能减退症、肾上腺功能不全、利尿剂或其他药物）以及低钠血症是急性还是慢性来决定治疗方法。有信息表明，绝大多数低钠血症是由非渗透性精氨酸血管加压素释放引起的。由于现在有了血管加压素 V2 受体阻滞剂，因此需要开展新的临床研究，以检验低钠血症是否仅仅是严重疾病的标志物，或者纠正低钠血症是否可以改善患者的生活质量。这种方法必须涉及不同低钠血症患者群体（包括晚期心力衰竭患者、肝硬化患者、癌症患者和老年人）的前瞻性随机研究。
