Hyponatraemia in heart failure: time for new solutions?

Hyponatraemia is very common in heart failure (HF), especially in decompensated patients. It is associated with increased mortality and morbidity and considered a marker of advanced disease. Recognition of hyponatraemia and its causes may help guide treatment strategy. Historically, therapy has primarily focused on water restriction, decongestion with loop diuretics in case of volume overload (dilutional hyponatraemia) and sodium repletion in case of depletion. In this review, we summarise the potential benefits of established and emerging HF therapies on sodium homeostasis, with a focus on dual vasopressin antagonists, angiotensin receptor-neprilysin inhibitors, sodium-glucose cotransporter 2 inhibitors and hypertonic saline, and propose a potential therapeutic approach for hyponatraemia in HF.

Therapeutic hypothermia and outcome in hyponatraemic encephalopathy secondary to maternal water intoxication

Misguided encouragement to consume large volumes of water during labour for pain relief results in dilutional hyponatraemia in mothers and their babies presenting with neurological dysfunction. We report three babies who were encephalopathic with seizures in the background of hyponatraemia secondary to maternal ingestion of large volumes of water and mild perinatal asphyxia. All babies underwent therapeutic hypothermia in addition to sodium supplementation with fluid restriction. Their neurodevelopment was appropriate for age. This case series highlights the dilemma that could arise with hyponatraemic encephalopathy and mild perinatal asphyxia in the first 6 hours of life, which is the window of opportunity for therapeutic hypothermia for hypoxic-ischaemic encephalopathy. It is important to educate pregnant mothers in labour on the adverse effects of excessive fluid ingestion.

Influenza A: another cause of SIADH?

The syndrome of inappropriate antidiuretic hormone (SIADH) secretion is a frequent cause of hyponatraemia. It is a dilutional hyponatraemia secondary to impaired urinary dilution in the absence of renal disease or any identifiable non-osmotic stimulus known to induce antidiuretic hormone secretion. SIADH can arise secondary to various respiratory tract infections; however, the association between SIADH and influenza A infection is described in only a few cases in the literature. The authors present a case report of influenza A that may have caused a profound SIADH-related hyponatraemia.

Polydipsia and intermittent hyponatremia

IntroductionHyponatraemia occurs in 4% of schizophrenic patients. Dilutional hyponatraemia, due to inappropriate retention of water and excretion of sodium, occurs with different psychotropic medications and could lead to hippocampal dysfunction. This complication is usually asymptomatic but can cause severe problems, as lethargy and confusion, difficult to diagnose in mentally ill patients.ObjectivesTo describe a case of a patient with psychotropic poli-therapy, admitted three times due to hyponatremia and the pharmacological changes that improved his condition.AimsTo broadcast the intermittent hyponatraemia and polydipsia (PIP), a not rare condition, suffered by treated schizophrenic patients and discuss its physiopathology and treatment thorough a case report.MethodsA 56-year schizophrenic male was admitted for presenting disorganized behavior, agitation, auditory hallucinations, disorientation, ataxia, vomits and urinary retention. He was on clomipramine, haloperidol and clotiapine (recently added), quetiapine, fluphenazine and clonazepam. After water restriction his symptoms improved and he was discharged. Twenty-five days later, he was readmitted for presenting the same symptoms and after water restriction, he was discharged. Five days later, he was again admitted and transferred to the psychiatric ward.ResultsHaloperidol, fluphenazine and clomipramine were replaced by clozapine. These changes lead him to normalize the hypoosmolality and reduce his water-voracity. Endocrinology team did not label this episode of SIADH due to its borderline blood and urine parameters.ConclusionsHyponatremia is frequent in schizophrenic patients and may have severe consequences. Therefore, a prompt recognition and treatment is warranted.Disclosure of interestThe authors have not supplied their declaration of competing interest.

Pathogenesis of solute-free water retention in experimental ascitic cirrhosis: is vasopressin the only culprit?

Adrenergic hyper-function reduces renal excretion of water. In advanced cirrhosis, hypersecretion of vasopressin (antidiuretic hormone or ADH) is considered the cause of dilutional hyponatraemia. We show that in experimental cirrhosis sympatholytic agents (α2A-adrenoceptor agonists) are as effective as V2 antagonists to blunt water retention.