Glomerular filtration INDEX

Glomerular filtration rate (GFR) The volume of plasma that is filtered by the glomerulus per unit time, usually expressed as mL/minute or mL/minute/1.73 m2, which adjusts the value for body surface area. GFR is the primary index used to describe overall renal function. 

Estimation of the glomerular filtration rate (GFR) is considered a sensitive index of functional nephron mass (Newman and Price 1999). Point measurements of the plasma levels of several endogenous small molecules (urea, creatinine, 2-(a-mannopyranosyl)-L-tryptophan) or small (less than 66 kDa) proteins (cystatin C (y-trace), prostaglandin D synthase (15-trace protein), ai-microglobulin, p2-microglobulin, and retinol binding protein) have been used to assess GFR in many species. 

Robert, S. Zarowitz, B.J. Is there a reliable index of glomerular filtration rate in critically ill patients DICP, Ann. Pharmacother. 1991. 25 (2). 169 178. 

This ingenious method gave a rough index of blood flow through the kidneys. It was subsequently greatly developed by my old friend and former associate, Homer Smith. Measurements of discrete function of glomerular filtration rate and renal blood flow using mannitol, creatinine, and p-aminohippurate were developed later. 

After 20-30 min for equilibration, perfusate samples are collected to coincide with the start of urine collections at 5 to 15 min intervals. The urine volume depends on both perfusion pressure and oncotic pressure [102]. Perfusion pressure and flow are monitored continuously. Renal function is assessed from renal vascular resistance, urine flow, the ratio of l C-inulin in urine to plasma (U/Pinulin), glomerular filtration rate (GFR as inulin clearance UV/P) and the fractional excretion of sodium (FEjvja) potassium (FEj ). Inulin measurement can also be performed chemically. In some situations GFR is misleading as an index of "good function" in this model. For example, in the absence of an oncotic agent, a "reasonable" GFR is over 1 ml/ g/ min, however U/Pinulin is rarely more than 2, FENa is over 0.1 and histological examination shows extensive proximal necrosis within 20-40 min of initiating perfusion. It appears that in this situation the massive... 

The glomerular filtration rate (GFR) is therefore highly dependent on the capillary integrity and renal blood or plasma flow and is an important index of renal function. The way to measure GFR is described in the Methods section. For endogenous or exogenous substances that are neither reabsorbed nor secreted by the tubule, GFR (mL/min) is equivalent to clearance and corresponds to the volume of... 

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