Glomerular filtration rate measured creatinine clearance

Creatinine is poorly secreted and not subject to tubular reabsorption therefore, its clearance is a useful measure of the glomerular filtration rate. Although creatinine clearance tells us about only one aspect of renal function (i.e., filtration), it is an excellent indicator for assessing the severity of renal impairment. 

It is well known that both glomerular and tubular renal functions decline with age in at least one third of individuals. As a result there is greater variation in renal function in older subjects. Glomerular filtration rate can be predicted by creatinine clearance, which can be estimated based on measured serum creatinine (Sercr) concentration. One such formula is the Cochrane and Gault formula in which... 

Renal function is an indication of the physiological state of the kidney glomerular filtration rate (GFR) describes the flow rate of Altered fluid through the kidney, while creatinine clearance rate (Ccr) is the volume of blood plasma that is cleared of creatinine per unit time, and is a useful measure for approximating the GFR. Most clinical tests use the plasma concentrations of the waste substances of creatinine and urea, as well as electrolytes, to determine renal function. The nephron is the functional unit of the kidney (Figure 10.1) it consists of two parts ... 

Bauer JH, Brooks CS, Burch RN. Clinical appraisal of creatinine clearance as a measurement of glomerular filtration rate. Am J Kidney Dis 1982 2 337-46. 

The use of hypertonic saline was first introduced in the clinic by Schilsky et al. [19] who concluded than when 3% saline was used as a vehicle for cisplatin, no renal toxicity was observed as measured by serum creatinine and creatinine clearance in patients treated with a high dose of cisplatin. However, when Cr-EDTA was used as a measure of glomerular filtration rate, a significant decrease in the latter was observed despite the use of 3% saline [12,13]. Thus the interest of hypertonic saline in the prevention of high dose cisplatin nephrotoxicity will have to be further delineated... 

Van Acker BA, Koomen GC, Koopman MG, de Waart DR, Arisz L. Creatinine clearance during cimetidine administration for measurement of glomerular filtration rate. Lancet 1992 340 1326-9. 

Formal measures of glomerular filtration rate (GFR), using intravenous inulin or radio-iodinated sodium iothalamate, will not have been performed on most patients with relative renal failure in ordinary clinical practice. Of several alternatives in adults, creatinine (Cr) clearance (CrCL) is probably the most commonly employed, and uses the familiar formula ... 

TRP = 1 — Cp/Ccr depends on the assumption that creatinine clearance is a precise measure of glomerular filtration rate. This is an unjustified assumption (H8), and it is therefore probably wiser to use the term Cp/Ccr- Whichever term is used, discrimination between euparathyroid... 

Glomerular filtration rate (GFR) is the best global estimate of renal function. Insulin clearance is the gold standard for GFR measurement. Greatinine clearance may also be used, although its value exceeds the exact value for GFR because creatinine is not exclusively excreted by the tubules but also secreted by the tubules. This discrepancy increases as GFR falls. Serum creatinine measurement does not reflect abnormal renal function until after GFR has been reduced to at least 50% of the baseline value [6]. 

A special case is that of endogenous creatinine. This is normally produced at a constant rate as the end product of muscle metabolism and therefore circulates in plasma at a constant concentration it is freely filtered at the glomerulus but neither reabsorbed nor effectively secreted in the tubule. Secretion has been reported in some species, but it is sufficiently small so that it does not significantly contribute to creatinine excretion except at low filtration rates. Like insulin clearance, that of creatinine can therefore serve as a convenient measure of the glomerular filtration rate. Creatinine possesses a great advantage over insulin in that its clearance can be measured without the need of an equilibrating infusion [18,19]. 

Early kidney disease is difficult to detect. The urinalysis is normal in early lead nephropathy and the blood urea nitrogen and serum creatinine increase only when two-thirds of kidney function is lost. Measurement of creatinine clearance can often detect earlier disease as can other methods of measurement of glomerular filtration rate. An abnormal Ca-EDTA mobilization test has been used to differentiate between lead-induced and other nephropathies, but this procedure is not widely accepted. A form of Fanconi syndrome with aminoaciduria, glycosuria, and hyperphosphaturia indicating severe injury to the proximal renal tubules is occasionally seen in children. 

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