Reconsidering Chronic Hyponatremia in Psychosis

Abstract

medical patients) showing that patients with CHN had an increased risk of death in the hospital, at 1 year, and at 5 years. These findings have obvious implications for quality of life and raise numerous questions. When does CHN become symptomatic in psychotic populations? Is the CNS of psychotic individuals unusually vulnerable to the consequences of CHN? When should CHN be treated with medications? What dosage and duration are appropriate? A New Treatment OptionVaptans have generated great expectation as a treatment option for CHN. 21 One US Food and Drug Administration (FDA)-approved vaptan, tolvaptan, is a selective vasopressin (V 2 ) receptor antagonist. 22 It works by blocking the effects of the pituitary hormone arginine vasopressin (AVP) on the V 2 receptors on the renal collecting duct cells. The Study of Ascending Levels of Tolvaptan (SALT) trial established short-term (30 days) efficacy of tolvaptan for elevating and maintaining serum sodium levels among patients with CHN of diverse etiologies. The SALT trial included a subgroup of psychotic patients with idiopathic CHN and demonstrated that short-term treatment with tolvaptan is effective and safe in this population as well. 23 A multiyear study with psychotic patients confirmed that tolvaptan is effective and safe over long periods of time. 24 Another oral vaptan, lixivaptan, is effective and safe when used to treat CHN in psychotic patients 25,26 but is not yet FDA-approved.Vaptans are seldom used in psychiatric institutions. The available information regarding vaptans and psychosis comes almost entirely from pharmaceutical industry-sponsored clinical trials, and, as a result, little "real-world" experience has been reported. The metric used to demonstrate vaptan efficacy has been serum sodium levels, which are thought to be of limited clinical value within the mental health context. There are no specific guidelines regarding treatment of CHN in psychotic populations, which means that clinicians need to rely solely on their clinical experience and good judgment on a case-by-case basis. Finally, the cost of tolvaptan ($250 per tablet) has raised significant cost-benefit considerations.Addendum: As this article was going to press, the authors were notified that 3 patients enrolled in a 3-year tolvaptan study and its extension trial of about 1,400 patients with autosomal dominant polycystic kidney disease (ADPKD) developed significant (> 3 × ULN) increases in serum alanine aminotransferase with concomitant, clinically significant (> 2 × ULN) increases in serum total bilirubin. Two of these cases were previously reported in the publication of the placebo-controlled study in ADPKD. 1 These patients were treated with doses between 60 and 120 mg/d. The maximum FDA-approved dose of tolvaptan in the US for the indication of euvolemic and hypervolemic hyponatremia is 60 mg/d. Tolvaptan is not currently approved for the treatment of ADPKD. Also, in published results from populations with other diseases treated with tolvaptan over multiple years, liver enzyme a...

Catatonia Due to General Medical Conditions in Psychiatric Patients: Implications for Clinical Practice

“…The most common electrolyte imbalance in patients with schizophrenia is hyponatremia, with a prevalence of 7-10% in inpatient settings [35]. The so-called psychogenic polydipsia may sometimes cause hyponatremia, via excess consumption of water, and its incidence in chronic patients with schizophrenia may be up to 11-20% [36].…”