In the physiology of the kidney, free water clearance (CH2O) is the volume of blood plasma that is cleared of solute-free water per unit time. An example of its use is in the determination of an individual's state of hydration. Conceptually, free water clearance should be thought of relative to the production of isoosmotic urine, which would be equal to the osmolarity of the plasma. If an individual is producing urine more dilute than the plasma, there is a positive value for free water clearance, meaning pure water is lost in the urine in addition to a theoretical isoosmotic filtrate. If the urine is more concentrated than the plasma, then free water is being extracted from the serum, giving a negative value for free water clearance. A negative value is typical for free water clearance, as the kidney usually produces concentrated urine except in the cases of volume overload by the individual.
Other articles related to "free water clearance, water, free water":
... Free water clearance can be used as an indicator of how the body is regulating water ... A free water clearance of zero means the kidney is producing urine isosmotic with respect to the plasma ... zero imply that the kidney is producing dilute urine through the excretion of solute-free water ...
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