Nephrology · Critical Care
Free Water Clearance calculator
Enter the published formula inputs below to calculate and interpret this score.
Clinical inputs
Result
Complete all required inputs to calculate the score.
Formula inputs
- Urine flow (mL/min)Accepted range: 0.01 to 50
- Urine osmolality (mOsm/kg)Accepted range: 50 to 1200
- Serum osmolality (mOsm/kg)Accepted range: 250 to 350
Primary source
Rose BD, Post TW. Clinical Physiology of Acid-Base and Electrolyte Disorders. 5th ed. McGraw-Hill; 2001. DOI: 10.1036/0071346821. PMID: 11228183. Scope: free-water clearance (mL/min) = urine flow × (1 − urine osmolality / serum osmolality); negative values indicate net free-water reabsorption. (2001)
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