Acute Dysnatremias - a dangerous and overlooked clinical problem

Abstract

Background: Dysnatremias are common electrolyte disturbances with significant morbidity and mortality. In chronic dysnatremias a slow correction rate (<10 mmol/L/24 h) is indicated to avoid neurological complications. In acute dysnatremias (occurring <48 h) a rapid correction rate may be indicated. Most guidelines do not differ between acute and chronic dysnatremias. In this review, we focus on the evidence-based treatment of acute dysnatremias.

Methods: A literary search in PubMed and Embase. A total of 72 articles containing 79 cases were included, of which 12 cases were excluded due to lack of information.

Results: Of 67 patients (70% women) with acute dysnatremia, 60 had hypo- and 7 had hypernatremia. All patients with hyper- and 88% with hyponatremia had a rapid correction rate (> 10 mmol/L/24 h). The median time of correction was 1 day in patients with hypo- and 2.5 days in patients with hypernatremia. The mortality was 7% in patients with hypo- and 29% in patients with hypernatremia.

Interpretation: Severe acute dysnatremias have significant mortality and require immediate treatment. A rapid correction rate may be lifesaving and is not associated with neurological complications. Chronic dysnatremias, on the other hand, are often compensated and thus less severe. In these cases a rapid correction rate may lead to severe cerebral complications.

Keywords: Acute dysnatremia; Ecstasy-associated hyponatremia; Exercise-associated hyponatremia; Hypernatremia; Hyponatremia; Psychogenic polydipsia; Salt intoxication; Water intoxication.

Fig. 1

Study flow-chart in 79 patients with acute dysnatremias

Fig. 2

Dysnatremia and the effects on the brain. In normal condition, there is osmotic equilibrium. Water diffuses between the extracellular volume (ECV) and intracellular volume (ICV). In acute hyponatremia, water from ECV diffuses into ICV (water is drawn into cells), which can lead to brain edema and herniation. In acute hypernatremia, water from ICV diffuses into ECV (water is extracted from the cells), which can lead to reduced brain volume. This can cause rupture of cerebral veins, focal and subarachnoid bleeding. Upon rapid correction of acute hyponatremia or acute hypernatremia, the brain can be returned to normal condition (normonatremia)