Electrolyte-Free Water Clearance Calculator

Input Parameters
Results
Calculated values and interpretation.
Urine/Plasma Electrolyte Ratio---
CeHâ‚‚O (hourly)--- mL/h
CeHâ‚‚O (24-hour)--- mL/24h

Enter values to see interpretation.

Clinical Interpretation Guide

Ratio < 1 (Positive CeHâ‚‚O): Indicates electrolyte-free water excretion. The kidneys are appropriately diluting urine, contributing to a rise in serum sodium. Fluid restriction is likely to be effective.

Ratio > 1 (Negative CeHâ‚‚O): Indicates electrolyte-free water retention. The kidneys are concentrating urine, which will tend to lower serum sodium. Fluid restriction alone is unlikely to be sufficient; other interventions may be needed.

Ratio = 1: No net free water clearance. Water intake is balanced by excretion, with no expected change in serum sodium from renal water handling.

Note: When the U/P ratio is less than 1, serum sodium will rise as long as fluid intake remains below the sum of CeHâ‚‚O and insensible losses.