Efficacy of Oral Urea Supplementation in Patients With SIAD Not Adequately Controlled With Fluid Restriction
Hyponatremia due to SIAD is frequently insufficiently corrected by fluid restriction alone, which remains the first-line therapy but is often poorly tolerated. Urea supplementation is recommended as second-line therapy. This prospective study evaluates the effectiveness of oral urea supplementation in patients with chronic SIAD and persistent hyponatremia despite fluid restriction.
• Confirmed diagnosis of SIAD established prior to study inclusion, defined as:
• Plasma sodium concentration \<135 mmol/L
• Plasma osmolality \<300 mOsm/kg
• Urine osmolality \>100 mOsm/kg
• Urine sodium concentration \>30 mmol/L
• Intact adrenal and thyroidal function and no use of diuretics in the last 4 weeks
• Clinical euvolemia, defined as an absence of signs of hypovolemia (orthostasis, tachycardia, decreased skin turgor, dry mucous membranes) or hypervolemia (edema, ascites)
⁃ Fulfillment of all diagnostic criteria at baseline (day 0) was not mandatory, as the diagnosis of SIAD had already been established prior to study inclusion based on overall clinical assessment.
⁃ \- Written informed consent obtained