| Assessment of renal function
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| Renal clearance and the glomerular filtration rate are important characteristics of kidney function
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The renal clearance is the volume of plasma (in milliliters) that the kidney clears of a given substance per unit of time (minutes). The concept of glomerular filtration rate (GFR) is derived from this and is the most important characteristic describing kidney function. GFR could be estimated by measuring the clearance of a substance, such as polysaccharide inulin, that is removed from the body only through the kidneys, and that is neither secreted nor reabsorbed in the renal tubules. The amount of inulin filtered from plasma (plasma concentration, Pin, multiplied by GFR) equals the amount recovered in urine (i.e. the urinary concentration, Uin, times the rate of urine formation rate, V). One can present this in the form of an equation:
From this the GFR can be calculated as:
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| The expression <graphic board> is called the renal clearance and the renal clearance of inulin equals the GFR. The average GFR is 120 mL/min for men and 100 mL/min for women.
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