The VExUS System Has a Limited Clinical Impact in the Evaluation and Management of Hypoosmolar Hyponatremia: A Single-Center Observational Study

Abstract Background Hyponatremia is the most frequent electrolyte disturbance in hospitalized patients, yet assessing volume status remains a diagnostic challenge. The Venous Excess Ultrasound (VExUS) system has been proposed as a noninvasive method to evaluate volume overload and guide management. However, data on its clinical impact in hypoosmolar hyponatremia are limited. Objective To investigate whether the VExUS system can support the management of acute hypoosmolar hyponatremia, detect discrepancies with physical examination in assessing volume status, and predict clinical outcomes. Methods This single-center observational study included adult inpatients with moderate or severe hypoosmolar hyponatremia (plasma sodium <=130 mEq/L). Patients underwent a standard clinical evaluation (history and physical examination) and a VExUS-based ultrasound assessment of at least two venous regions (inferior vena cava, hepatic veins, portal vein, or renal veins). Internal jugular vein measurements were used when feasible. The treating physicians of the patients were blinded to the ultrasound findings. Serum sodium levels were measured at 24, 48, and 96 hours. Treatments were based on existing clinical guidelines, and any changes in therapy were documented. Results Twenty-eight patients were enrolled, and two were excluded due to inadequate ultrasound data or new-onset cirrhosis. VExUS classification differed from clinical examination in 65.4 percent of patients (17 of 26), yet these discrepancies did not lead to significant differences in serum sodium trends or management changes at 24, 48, or 96 hours (p>0.05). Only four patients required therapeutic adjustments within 24 hours, and one displayed discrepant volume classifications. The VExUS system showed limited ability to distinguish euvolemia in patients with SIADH and demonstrated minimal correlation with laboratory parameters such as NT-proBNP and CA-125. Conclusions While ultrasound assessment is noninvasive and potentially useful, this study found that discrepancies in VExUS-based volume status classification did not significantly alter clinical outcomes or treatment strategies in hospitalized patients with hypoosmolar hyponatremia. The VExUS method should not replace standard complementary evaluations recommended by hyponatremia guidelines, although it may have a niche role when ruling in or out hypervolemia in selected cases.