Glomerular Filtration is Easy to Measure From Inulin or Creatinine Clearance

Glomerular Filtration is Easy to Measure From Inulin or Creatinine Clearance

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Urinary System Glomerular Filtration is Easy to Measure From Inulin or Creatinine Clearance * Renal Clearance- the volume of blood plasma from which a particular waste is completely removed in 1 minute. * Two substances are used to measure GFR: * Inulin : a polysaccharide which is not metabolized by the body or reabsorbed from the urine. * Inulin is not found in the body and must be injected. * This substance gives the most accurate results and is used for research purposes. * Creatinine : a breakdown product from creatine phosphate, which is naturally found in the blood. * Not quite as accurate as inulin (about 10% is reabsorbed), but often used in medicine, since no injection is required. Using Inulin in Measuring GFR * Is only filtered by the kidney; it is neither reabsorbed nor secreteted * Since no inulin is reabsorbed from or secreted into the tubule, the amount filtered into the tubule at the glomerulus must equal the amount appearing in the urine
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Unformatted text preview: P X GFR = U X V * P = plasma concentration of inulin, in mg/mL * GFR = glomerular filtration rate of plasma, in mL/min * U = urine concentration of inulin, in mg/mL * V = rate of urine production, in mL/min * Solving the equation for GFR will give: GFR = (U X V)/P Creatinine * Creatinine is a by product of muscle metabolism * Serum creatinine level and "creatinine clearance" are different ways of determining kidney function. * The amount produced is relatively stable in a given person and is dependent on muscle mass * The creatinine level in the serum is therefore determined by the rate it is being removed, which is roughly a measure of kidney function. * If kidney function falls (say a kidney is removed to donate to a relative), the creatinine level will rise. * Normal is about 1 for an average adult....
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This note was uploaded on 01/30/2012 for the course BSC BSC1085 taught by Professor Sharonsimpson during the Fall '10 term at Broward College.

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