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In these cases, clearance is almost synonymous with renal clearance or renal plasma clearance. Each substance has a specific clearance that depends on how the substance is handled by the nephron. Clearance is a function of 1) glomerular filtration , 2) secretion from the peritubular capillaries to the nephron , and 3) reabsorption from the ...
Clearance is therefore expressed as the plasma volume totally free of the drug per unit of time, and it is measured in units of volume per units of time. Clearance can be determined on an overall, organism level («systemic clearance») or at an organ level (hepatic clearance, renal clearance etc.). The equation that describes this concept is:
The glomerular filtration rate is the flow rate of filtered fluid through the kidney. The creatinine clearance rate (C Cr or CrCl) is the volume of blood plasma that is cleared of creatinine per unit time and is a useful measure for approximating the GFR. Creatinine clearance exceeds GFR due to creatinine secretion, [1] which can be blocked by ...
At its simplest, the kidney produces urine composed of solute and pure (solute-free) water. How rapidly the kidney clears the blood plasma of a substance (be it water or solute) is the renal clearance, which is related to the rate of urine production. The rate at which plasma is cleared of solute is the osmolal clearance; the rate at which ...
Therefore, the urinary and plasma concentrations of sodium must be compared to get an accurate picture of kidney clearance. In clinical use, the fractional excretion of sodium can be calculated as part of the evaluation of acute kidney failure in order to determine if hypovolemia or decreased effective circulating plasma volume is a contributor ...
X is the analyte substance; C x is the renal plasma clearance of X; C in is the renal plasma clearance of inulin. Creatinine is sometimes used instead of inulin as the reference substance; for example, the calcium-creatinine clearance ratio is used in an attempt to distinguish between different causes of a high plasma calcium concentration. [3]
The rate therefore measured is the quantity of the substance in the urine that originated from a calculable volume of blood. Relating this principle to the below equation – for the substance used, the product of urine concentration and urine flow equals the mass of substance excreted during the time that urine has been collected.
where C is the concentration [mol/m 3]; t is the time [s]; K is the clearance [m 3 /s]; V is the volume of distribution [m 3]; From the above definitions it follows that is the first derivative of concentration with respect to time, i.e. the change in concentration with time.