Hyponatraemia in ageing

Abstract

Hyponatraemia is the most common electrolyte disorder in both inpatient and outpatient settings and mostly affects older adults, in whom intrinsic factors (such as chronic heart, liver or kidney diseases and malignancies) and extrinsic factors (such as polypharmacy and malnutrition) favouring hyponatraemia are highly prevalent. Importantly, its occurrence is expected to increase exponentially with global warming. Chronic hyponatraemia is associated with an increased risk of falling, osteoporosis and fractures, attention deficits, and even mortality. In the past two decades, a growing number of studies have suggested that correcting hyponatraemia improves clinical outcomes, outlining hyponatraemia management as a part of promoting healthy ageing. In addition, SGLT2 inhibitors and protein supplementation have been shown to be efficacious in treating hyponatraemia, both of which represent attractive and holistic treatment options in older adults. However, despite hyponatraemia being encountered in all medical specialties, its clinical burden is often overlooked, partly due to low awareness but also to low confidence in applying diagnostic and therapeutic algorithms. In this Review, we aim to depict the consequences of hyponatraemia, characterize the most common aetiologies in older individuals, and finally detail the diagnostic pathway as well as the benefits and limitations of the available treatment options. Hyponatraemia is associated with poor health outcomes and increased mortality, particularly for hospital inpatients. Risk of hyponatraemia increases with age due to comorbidities, polypharmacy and poor nutrition. This Review discusses the causes of hyponatraemia and its clinical management, with a particular focus on older populations.