Management of hyponatremia in the hospital: Interim results of a disease-based registry

Purpose: Hyponatremia (HN), the leading electrolyte abnormality in hospitalized patients, is an independent predictor of increased mortality in patients with cirrhosis, heart failure (HF), neurologic disorders, and in general hospitalized patients. Since little is known about its current management, a registry was conducted to analyze HN therapies and characterize their relative efficacy.

Methods: This is a multicenter, observational registry of adults with euvolemic (SIADH) and hypervolemic (cirrhosis, HF, and nephrotic syndrome. HN is defined as serum sodium concentration ([Na+]) ≤ 130 mmol/L, with overcorrection as > 12 unit change in 24h.  Target enrollment is 3,500 patients in US and EU. After informed consent or waiver, medical records of eligible patients were abstracted and summarized using descriptive statistics. 

Results: A total of 1672 US patients were analyzed through April 2012.  The mean entry and discharge [Na+] were 126.4±7.5 mmol/L, and 131.7±5.0 mmol/L, respectively. HN etiology was HF (34%), SIADH (36%), cirrhosis (16%), and nephrotic syndrome (3%). HN was the admitting diagnosis in 25%, and was chronic in 40%. A total of 41% remained hyponatremic at discharge, most commonly in patients receiving only fluid restriction (FR). Overall, 44% of patients received no treatment, and monotherapies of FR (29%), normal saline (NS) (21%), any pharmacologic therapy (5%), and hypertonic saline (1.3%). Combination therapy was initially prescribed in 14%. Overcorrection of [Na] developed in 2% overall; 29% receiving hypertonic saline only, 5% each receiving NS only, 4% on vaptans alone, 2% were untreated, and <1% receiving FR only.  

Conclusion: Patients are often admitted with chronic HN and frequently have SIADH or HF. One-third of patients received no treatment for HN, with FR the most common intervention. Patients are frequently discharged with persistent HN. Overcorrection most commonly occurred in patients receiving hypertonic saline. These data suggest HN in hospitalized patients is suboptimally managed.