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Free Water Clearance
Aka: Free Water Clearance
- See Also
- Renal Function
- Indications
- Quantitate renal concentrating function
- Physiology
- Calculates the amount of free water to add or subtract from urine to make it isoosmotic with plasma
- Calculation
- cH2O = uV - (uOsm x uV)/pOsm
- where cH2O = Free Water Clearance
- where uV = Urine Volume per unit time
- where uOsm = Urine Osmolality
- where pOsm = plasma osmolality
- Interpretation
- Free Water Clearance positive
- Urine less concentrated than plasma
- Decreased Antidiuretic Hormone (ADH)
- Free Water Clearance negative
- Urine is more concentrated than plasma
- Increased Antidiuretic Hormone (ADH)
- Resources
- Free Water Clearance (Wikipedia)
- https://en.wikipedia.org/wiki/Free_water_clearance
- References
- Goldberg (2014) Clinical Physiology, Medmaster, p. 34