Management of SIADH-related hyponatremia due to psychotropic medications - An expert consensus from the Association of Medicine and Psychiatry

Abstract

Objective: Hyponatremia is the most common electrolyte imbalance encountered in clinical practice and is associated with negative healthcare outcomes and cost. SIADH is thought to account for one third of all hyponatremia cases and is typically an insidious process. Psychotropic medications are commonly implicated in the etiology of drug induced SIADH. There is limited guidance for clinicians on management of psychotropic-induced SIADH.

Methods: After an extensive review of the existing literature, clinical-educators from the Association of Medicine and Psychiatry developed expert consensus recommendations for management of psychotropic-induced SIADH. A risk score was proposed based on risk factors for SIADH to guide clinical decision-making.

Results: SSRIs, SNRIs, antipsychotics, carbamazepine, and oxcarbazepine have moderate to high level of evidence demonstrating their association with SIADH. Evaluation for an avoidance of medications that cause hyponatremia is particularly important. Substitution with medication that is less likely to cause SIADH should be considered when appropriate. We propose an algorithmic approach to monitoring hyponatremia with SIADH and corresponding treatment depending on symptom severity.

Conclusions: The proposed algorithm can help clinicians in determining whether psychotropic medication should be stopped, reduced or substituted where SIADH is suspected with recommendations for sodium (Na+) monitoring. These recommendations preserve a role for clinical judgment in the management of hyponatremia with consideration of the risks and benefits, which may be particularly relevant for complex patients that present with medical and psychiatric comorbidities. Further studies are needed to determine whether baseline and serial Na+ monitoring reduces morbidity and mortality.

Keywords: Antidepressants; Antipsychotics; Hyponatremia; Mood stabilizers; Psychoactive medications; SIADH.

Fig. 1.

Algorithm for the differential diagnosis of hyponatremia: Differential diagnosis of hyponatremia. The above algorithm outlines a clinical approach to the differential diagnosis of hyponatremia. BP = blood pressure; Na = sodium; Osm = osmolality; SIADH = syndrome of inappropriate anti-diuretic hormone. Modified from Maxine A. Papadakis, Stephen J. McPhee, Michael W. Rabow, Current Medical Diagnosis and Treatment 2021, McGraw Hill.

Fig. 2.

Proposed risk scoring & management algorithm of psychotropic medication induced SIADH*. * BMI = body mass index, SSRI = selective serotonin reuptake inhibitor, SNRI = serotonin norepinephrine reuptake inhibitor. Disclaimer: The proposed risk scoring and algorithm is not validated by randomized control studies and is based on the compilation of the available clinical data and expert consensus.