Nephrology · Critical Care
Free Water Clearance calculator
Enter the published formula inputs below to calculate and interpret this score.
Clinical inputs
Result
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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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