Kidney Week

Abstract: TH-PO0066

Precision Sodium Targeting in CRRT

Session Information

• Fluid, Electrolyte, and Acid-Base Disorders: Clinical Research
  October 22, 2026 | Location: Exhibit Hall A, Convention Center
  Abstract Time: 10:00 AM - 12:00 PM

Category: Fluid, Electrolytes, and Acid-Base Disorders

• 1102 Fluid, Electrolyte, and Acid-Base Disorders: Clinical

Authors

• Zeng, Billy, University of California San Francisco, San Francisco, California, United States

Billy Zeng, MD

• Lo, Lowell J., University of California San Francisco, San Francisco, California, United States

Lowell J. Lo, MD

Background

Precise regulation of serum sodium (Na) is essential in CRRT (continuous renal replacement therapy) patients with liver failure or cerebral edema, where narrow therapeutic windows are required to manage intracranial pressure. Standard predictive tools like the Adrogué-Madias equation are static, closed-system bolus therapy fails to account for the continuous effects of CRRT clearance and hypertonic saline (HTS) infusions. This mismatch between existing models and continuous therapy complicates prospective targeting and increases reliance on reactive adjustments. We developed a kinetic modeling framework and a web-based simulator to provide prediction of Na trajectories during CRRT over time.

Methods

We used the Law of Conservation of Mass to derive ordinary differential equations for Na trajectory. Two distinct models were developed: 1) a constant-volume model resulting in an exponential decay solution, and 2) an active net ultrafiltration (UF) model where volume shrinks linearly, resulting in a power-law solution. The models integrate variables including saline infusion rate (R), saline infusion concentration (Na_inf), dialysate sodium (Na_d), and machine clearance (k). We implemented the solutions into a responsive web-based simulator.

Results

The target steady state sodium (Na_ss) is the flow-weighted average of all inputs: Na_ss = (R×Na_inf + k×Na_d) / (R + k). Typical values of net UF has negligible impact on Na trajectory. The resulting web tool provides useful visualization of Na trajectories, allowing for timely prescription changes.

Conclusion

Sodium kinetics during CRRT are predictable using a first-order kinetic framework. While ultrafiltration has a minimal immediate impact on Na concentration, it has a slight acceleration effect over time. Our simulator provides clinicians with a rigorous proactive approach to CRRT improving the safety and precision of sodium management.