Safety and Efficacy of Urea for Hyponatremia

Background and Objective: Urea is an alternative for treatment of hyponatremia however, its use has not been widely studied. The purpose of this study was to evaluate the safety and efficacy of urea for the treatment of hyponatremia. Methods: A retrospective cohort of patients with hyponatremia (serum sodium <135 mEq/L) of any cause who received at least 1 dose of urea during hospitalization and no prior use of urea. Serum sodium levels were collected at baseline and for 4 days or until urea was discontinued, whichever occurred first. The primary outcome was the serum sodium change between baseline and discharge or urea discontinuation. Results: Median serum sodium increased 2 [IQR, 0-4] mEq/L per day after urea administration at a median dose of 30 g/day. A significant difference in serum sodium was observed between baseline and discharge or discontinuation (124.2 ± 4 vs 130.1 ± 5.1; P < .001) and serum blood urea nitrogen (BUN) levels (18.4 ± 13.1 vs 41.1 ± 26.6; P ≤ .001). Serum sodium overcorrection (increase >8 mEq/L in 24 hours) occurred in 6 patients (8%). Urea was discontinued in 39 patients (53%); 20 discontinuations were due to patient intolerance. Conclusion: Urea appears to be an effective treatment for hyponatremia; however, patient tolerance, the rate of serum sodium overcorrection, and outpatient affordability may limit its use.