Acute symptomatic hyponatraemia is a medical emergency, and current practice guidelines have adapted to recommend the use of bolus hypertonic saline in this setting; however recent trial data have emphasised that caution must be taken to prevent overcorrection when the duration of hyponatraemia is unclear. Chronic asymptomatic hyponatraemia is traditionally thought of as clinically benign and is thus often underinvestigated and undertreated. Traditional treatments for SIAD have been limited to date by poor efficacy, side-effects, cost or lack of supportive randomised control trial data. The past two years have seen the publication of several much-needed prospective randomised controlled trials that have demonstrated modest effects of fluid restriction in patients with chronic SIAD, albeit with good tolerability and safety, thereby emphasising the need for second-line therapies. Cost-reduction, more widespread reimbursement and use of a lower starting dose may allow expansion of the use of tolvaptan in treatment of SIAD. Recent studies have also given cause for optimism for potential future treatments such as empagliflozin; an RCT examining use of the drug in chronic euvolemic and hypervolemic hyponatraemia is underway.

Treatment of hyponatraemia must be individualised to the patient, taking into account the acuity and cause of hyponatraemia, the indications for treatment, and treatment goals. For example, it is reasonable to consider an initial trial of fluid restriction in an asymptomatic patient with incidentally noted chronic SIAD. On the other hand, correction of hyponatraemia may be more urgent in patients awaiting chemotherapy for example, and in this scenario early consideration of a low dose of dose of tolvaptan (7.5 mg) is appropriate.

It is becoming increasingly clear that treatment of chronic hyponatraemia is associated with reduction in length of hospital stay, improvements in gait and mentation, and a reduction in mortality. Mortality rates associated with hyponatraemia have been shown to differ according to volume status, and this should be considered when designing and interpreting future outcome studies. Prospective studies, employing effective treatments that will increase plasma sodium concentration by a clinically significant amount, in a large enough cohort to classify patients by volume status, are required to confirm the long-term clinical benefits of chronic hyponatraemia treatment.

Fuente: Ther Adv Endocrinol Metab 2022, Vol. 13: 1–16    |


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