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.
Read more about Free Water Clearance: Overview, Calculation, Interpretation
Famous quotes containing the words free and/or water:
“We enter parliament in order to supply ourselves, in the arsenal of democracy, with its own weapons.... If democracy is so stupid as to give us free tickets and salaries for this bear’s work, that is its affair.... We do not come as friends, nor even as neutrals. We come as enemies. As the wolf bursts into the flock, so we come.”
—Joseph Goebbels (1897–1945)
“The water never formed to mind or voice,
Like a body wholly body, fluttering
Its empty sleeves; and yet its mimic motion
Made constant cry,”
—Wallace Stevens (1879–1955)