Introduction

Hypoaldosteronism is characterized by hyperkalemia, and/or hypovolemic hyponatremia (HH), often accompanied by metabolic acidosis. HH is typical of hypoaldosteronism, whereas euvolemic hyponatremia (EH) is not. The purpose of the current study is to describe the characteristics of hyponatremia in hypoaldosteronism and elucidate whether EH can be considered part of the disease’s spectrum.

Methods

In a hypoaldosteronism cohort, we analyzed the factors associated with hyponatremia, comparing the characteristics of EH and HH and their associated factors. Correlation analyses of mineralocorticoid biomarkers, such as the transtubular potassium gradient (TTKG), the urinary Na+/K+ ratio (UNa+/UK+) with serum, and urinary electrolytes were performed in both types of hyponatremia.

Results

Of 112 hypoaldosteronism episodes, 77.7% were ≥65 years old, 44.6% were women, and 80 (71.4%) had hyponatremia. Hyponatremia was negatively associated with the presence of chronic kidney disease, and positively with a hypovolemic state, malnutrition, a prior history of hyponatremia, and glucocorticoid therapy. HH: 61/80 and EH: 19/80 episodes. HH was associated with an age ≥65 years and the use of diuretics, as well as factors related to an aldosterone deficit and/or mineralocorticoid resistance. In HH but not in EH, urinary potassium was correlated with the TTKG, and urinary sodium with both the TTKG and the UNa+/UK+.

Conclusion

Both HH and EH can be observed in hypoaldosteronism. However, only the former would be related to insufficient mineralocorticoid activity.

Significance statement

Isolated hypoaldosteronism is a poorly understood and underdiagnosed endocrinological disorder, classically recognized only when hyperkalemia is present. The development of hypovolemic hyponatremia, however, is also easily explained by the physiopathology of the disorder. The current study addresses the features of hyponatremia when found in the context of mineralocorticoid insufficiency, and confirms an association between hypovolemic hyponatremia and isolated hypoaldosteronism. Thus, the clinical spectrum of hypoaldosteronism is extended to include hypovolemic hyponatremia as a frequent manifestation of the disorder.

中文翻译：

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孤立性醛固酮增多症是低血容量而非正常血容量低钠血症的原因

介绍

醛固酮增多症的特征是高钾血症和/或低血容量性低钠血症（HH），常伴有代谢性酸中毒。 HH 是醛固酮增多症的典型症状，而血容量正常的低钠血症 (EH) 则不是。本研究的目的是描述低醛固酮增多症中低钠血症的特征，并阐明 EH 是否可以被视为该疾病谱的一部分。

方法

在低醛固酮症队列中，我们分析了与低钠血症相关的因素，比较了 EH 和 HH 的特征及其相关因素。对两种类型的低钠血症进行了盐皮质激素生物标志物的相关性分析，例如经管钾梯度（TTKG）、尿Na+/K+比值（UNa+/UK+）与血清以及尿电解质。

结果

在 112 例低醛固酮增多症发作中，77.7% 为 ≥65 岁，44.6% 为女性，80 例（71.4%）患有低钠血症。低钠血症与慢性肾脏病呈负相关，与低血容量状态、营养不良、既往低钠血症病史和糖皮质激素治疗呈正相关。 HH：61/80 和 EH：19/80 集。 HH 与年龄≥65 岁、利尿剂的使用以及醛固酮缺乏和/或盐皮质激素抵抗相关的因素有关。在 HH 中，尿钾与 TTKG 相关，尿钠与 TTKG 和 UNa+/UK+ 相关，但在 EH 中则不然。

结论

HH 和 EH 均可在醛固酮增多症中观察到。然而，只有前者与盐皮质激素活性不足有关。

意义陈述

孤立性醛固酮增多症是一种人们知之甚少且诊断不足的内分泌疾病，通常仅在存在高钾血症时才被识别。然而，低血容量性低钠血症的发生也很容易用该疾病的病理生理学来解释。目前的研究探讨了在盐皮质激素不足的情况下发现的低钠血症的特征，并证实了低血容量性低钠血症与孤立性醛固酮增多症之间的关联。因此，低醛固酮增多症的临床范围扩大到包括低血容量性低钠血症，作为该疾病的常见表现。