Current Clinical Updates in Hyponatremia

Studies show that vaptans are effective in the treatment of hyponatremia and that patients with hyponatremia and STEMI face greater mortality risk.

Noting that “Recent studies have consistently demonstrated the common prevalence of hyponatremia in the hospital and intensive care settings, and how it correlates with untoward outcomes,” the authors of “Hyponatremia: Diagnosis, Complications, and Management Including V2 Receptor Antagonists,” published in the March 2011 issue of Current Opinion in Nephrology & Hypertension, undertook to review “the classification, diagnosis, and pathophysiology of hyponatremia,” examine the ways in which these factors may influence the management of, and evaluate the relative strengths and weaknesses of the available treatment options. They focus especially on data on vaptans and “their potential role to treat hyponatremia in the settings of the syndrome of inappropriate antidiuretic hormone secretion, congestive heart failure, and liver cirrhosis.” They conclude that vaptans will “likely play an important role in treating hyponatremia, given their clinical effectiveness and tolerability. Cost remains a hindrance for vaptans, and more studies are needed to further define their best utilization in hyponatremic patients.”

In “The Use of Vasopressin Receptor Antagonists in Hyponatremia,” published in the March issue of Expert Opinion on Investigational Drugs, Elhassan and Schrier also note that data indicates that hyponatremia is “fairly common in the intensive care and general hospital settings” and suggests “association of mild degrees of hyponatremia with untoward neurocognitive and musculoskeletal outcomes.” They review “new evidence linking mild chronic hyponatremia with unfavorable outcomes” and review the limitations and strengths of the available treatment options, including “new data on vaptans and their potential role to treat hyponatremia in different clinical settings.” In a conclusion that is remarkably similar to that reached by the authors in the article highlighted above (well perhaps not so remarkably — the two articles were written by the same authors), the authors of this study report that vaptans “are likely to play an important role in treating hyponatremia, given their clinical efficacy and tolerability. High cost remains an impediment for vaptans, and more studies are needed to further define their best use in hyponatremic patients.”

The author of “Vaptans for the Treatment of Hyponatremia,” published in the March 2011 issue of Nature Reviews Endocrinology, reported that vaptans are “useful for treating euvolemic hyponatremia associated with the syndrome of inappropriate antidiuretic hormone (SIADH), at least when it is chronic and/or minimally symptomatic.” However, because their effects “vary unpredictably from patient to patient,” vaptans are “less useful than hypertonic saline infusion in cases of acute, severe and symptomatic hyponatremia.” Vaptan therapy is “absolutely contraindicated in hypovolemic hyponatremia (in which total body water is reduced) and is ineffective in the vasopressin-independent form of inappropriate antidiuresis caused by constitutive activating mutations of V2 receptors.”

In “Long-term Prognostic Impact of Hyponatremia in the ST-elevation Myocardial Infarction,” the authors looked at in-hospital outcomes and long-term prognostic implications of hyponatremia in patients in the early phase of ST elevation myocardial infarction (STEMI) treated primarily with percutaneous coronary intervention (PCI). Compared to patients who did not develop hyponatremia (either prior to hospitalization or during treatment), hyponatremic patients “more frequently presented with reduced left ventricular systolic function, Killip class III or IV and were at increased risk of developing cardiogenic shock.” Patients who developed hyponatremia while hospitalized for treatment also had a higher incidence of acute renal failure. Patients who developed hyponatremia in the early phase of STEMI “were at higher risk of worse in-hospital clinical outcome” and experienced higher mortality rates during long-term follow-up.