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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 ...
The renal clearance ratio or fractional excretion is a relative measure of the speed at which a constituent of urine passes through the kidneys. [ 1 ] [ 2 ] It is defined by following equation: c l e a r a n c e r a t i o o f X = C x C i n {\displaystyle clearance\ ratio\ of\ X={\frac {C_{x}}{C_{in}}}}
Upon presentation of decreased renal function, it is recommended to perform a history and physical examination, as well as performing a renal ultrasound and a urinalysis. [ citation needed ] The most relevant items in the history are medications , edema , nocturia , gross hematuria , family history of kidney disease, diabetes and polyuria .
A simple means of estimating renal function is to measure pH, blood urea nitrogen, creatinine, and basic electrolytes (including sodium, potassium, chloride, and bicarbonate). As the kidney is the most important organ in controlling these values, any derangement in these values could suggest renal impairment.
Glomerular filtration rate (GFR) is the volume of fluid filtered from the renal (kidney) glomerular capillaries into the Bowman's capsule per unit time. [4] Central to the physiologic maintenance of GFR is the differential basal tone of the afferent (input) and efferent (output) arterioles (see diagram).
The primary sign of augmented renal clearance is an increase in the creatinine clearance well above that which would be considered normal. Commonly, ARC is defined as a creatinine clearance of greater than 130 mL/min, but the effects of increased clearance on therapy are not directly correlated to a specific number.
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:
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 plasma is cleared of solute-free water is the free water clearance.