300px|Diagram showing the basic physiologic mechanisms of the kidney The renal clearance ratio or fractional excretion is a  measure of the speed at which a constituent of urine passes through the kidneys. It is defined by following equation: See also  Kt/V 
300px|Diagram showing the basic physiologic mechanisms of the kidney The renal clearance ratio or fractional excretion is a relative measure of the speed at which a constituent of urine passes through the kidneys. It is defined by following equation: See also Clearance (pharmacology) Kt/V References
A
relative
A
Clearance (pharmacology)
A
References