Hyponatremia, especially if acute and severe, can be a life-threatening condition. Several conditions can trigger hyponatremia. In this review, we will discuss two conditions that can determine euvolemic hyponatremia: the cerebral/renal salt wasting (CRSW) syndrome and the syndrome of inappropriate secretion of antidiuretic hormone (SIADH), including the two subtypes: reset osmostat (RO) and nephrogenic syndrome of inappropriate antidiuresis (NSIAD) and their differential diagnoses. Despite the passage of over 70 years since its first description, to date, the true etiopathogenesis of CRSW syndrome, a rare cause of hypovolemic/euvolemic hyponatremia, is almost unknown. SIADH, including RO and NSIAD, is sometimes difficult to differentiate from CRSW syndrome; in its differential diagnosis, the clinical approach based on the evaluation of the extracellular volume (ECV) was proven insufficient. We therefore suggest a simple diagnostic algorithm based on the assessment of the degree of hyponatremia, urinary osmolality, and the assessment of the fraction of urate excretion (FEUa) in conditions of hyponatremia and after serum sodium correction, to be applied in children over 1 year of life.

中文翻译：

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1岁以上儿童抗利尿激素分泌不当综合征与脑/肾盐消耗综合征的鉴别诊断：一种简单算法的建议。

低钠血症，尤其是急性和严重的，可能会危及生命。有几种情况会引发低钠血症。在这篇综述中，我们将讨论可以确定正常血容量性低钠血症的两种情况：脑/肾盐消耗综合征（CRSW）和抗利尿激素分泌不当综合征（SIADH），包括两种亚型：重置渗透压（RO）和肾源性不适当抗利尿综合征（NSIAD）及其鉴别诊断。尽管自首次描述以来已经过去了 70 多年，但迄今为止，CRSW 综合征的真正发病机制是低血容量/正常低钠血症的罕见原因，几乎是未知的。SIADH，包括 RO 和 NSIAD，有时难以与 CRSW 综合征鉴别；在其鉴别诊断中，基于细胞外体积（ECV）评估的临床方法被证明是不够的。因此，我们建议采用一种简单的诊断算法，该算法基于对低钠血症程度、尿渗透压以及在低钠血症和血清钠校正后的尿酸盐排泄分数 (FEUa) 的评估，适用于 1 岁以上的儿童的生活。