In renal physiology,<unk>  <unk>  is the<unk>  amount of<unk>  excreted in the urine per unit time. Its value depends on urine flow rate, urine<unk>  concentration, and the concentration of bicarbonate in the urine (the loss of bicarbonate, a buffering agent, is physiologically equivalent to a gain in<unk> .<unk>  is commonly expressed in units of milliliters per minute (ml/min) and is given by the following equation: : where Variable Meaning<unk> <unk>  V volume of urine produced per unit time UNH4 urine concentration of ammonium UTA urine concentration of titratable<unk>  (e.g., phosphoric<unk> , sulfuric<unk>  UHCO3 urine concentration of bicarbonate
Net acid excretion
Free water clearance
Urea reduction ratio
Renal clearance ratio
Fractional excretion of sodium
Urine osmolality
Sucrose gap
Urine flow rate