Glomerular filtration rate measure

Dagoo T, Backman L, Mjornstedt L, Olausson M, Friman S. Progressive renal impairment in liver transplant recipients on a cyclosporine-based protocol 5 year follow-up with glomerular filtration rate measurements. Transplant Proc 1997 29 3116-3118. 

Blake GM, Roe D, Lazarus CR. Long-term precision of glomerular filtration rate measurements using Cr-EDTA plasma clearance. Nuclear Medicine Communications 1997 18 776-84. 

Horijn KW, Barendregt JNM, Lentjes EGWM, et al. Glomerular filtration rate measurement by single-shot injection of inuUn. Kidney Int 1994 46 252-259. 

The glomerular filtration rate (GFR) defines how much plasma water passes from the blood into the top of the nephron per minute. In health, the true GFR for a 70 kg adult is typically 100-120 ml/minute. Expressed another way, we can say that, in health, every minute each of the approximately 2 million glomeruli present in both adult kidneys filters between 0.05 and 0.06 pi of plasma water. The GFR is a good overall measure of renal function and the clinical laboratory has many ways of estimating its value. 

The glomerular filtration rate (GFR) measures the rate at which blood is filtered by the kidneys. 

Jenkins et al. developed a capillary electrophoresis system for the measurement of iohexol as a marker of the glomerular filtration rate (GFR) with a run time of 5.25 min and a coefficient of variation (CV) of 4.3% at 80 mg L" [121]. The GFR, calculated from the plasma clearance, had a reproducibility of 5.47 %. A similar approach (liquid chromatography-mass spectrometry with positive electrospray ionization after enrichment by solid phase extraction) was applied by Putschew et al. for the determination of iodinated contrast agents in treatment plant effluents and surface waters [118]. 

Uric acid is the end product of the purine metabolism. When uric acid excretion via the kidneys is disturbed, gout can develop (see p. 190). Creatinine is derived from the muscle metabolism, where it arises spontaneously and irreversibly by cyclization of creatine and creatine phosphate (see p. 336). Since the amount of creatinine an individual excretes per day is constant (it is directly proportional to muscle mass), creatinine as an endogenous substance can be used to measure the glomerular filtration rate. The amount of amino acids excreted in free form is strongly dependent on the diet and on the ef ciency of liver function. Amino acid derivatives are also found in the urine (e.g., hippu-rate, a detoxification product of benzoic acid). 

So the total clearance of any drug is given by Vd (1) X Ks (h ) = (Vd /fei) 1/h, and is expressed, as is for example glomerular filtration rate, as units of volume per time period. We will use this concept of measuring clearance later in this section, and in clinical applications in Section IV. Tables of drug clearance are commonly set alongside those for apparent volume of distribution of common drugs in textbooks which list kinetic data. 

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... 

Identify the patient at risk for CIN—For patients likely to have reduced kidney function a measurement of the SCr level and estimation of the glomerular filtration rate can be recommended, If the glomerular filtration rate is less than 50 mL/min/l, 73 m2, particularly in combination with other risk factors, consideration should be given to alternative imaging approaches. 

Inulin is used in an important test for renal failure called the inulin clearance method (Gretz et al., 1993 Chiu, 1994). As inulin is neither secreted nor reabsorbed in the kidney, it can be administered by injection to measure glomerular filtration rate. The relative amounts of inulin in the plasma and urine give an indication of renal function. 

Bailey RR, Rogers TGH, Tait JJ (1970) Measurement of glomerular filtration rate using a single injection of 51Cr-Edetic add. Anst. Arm Meu 19(3) 255-258 Brenner BM, Zatz R, Ichikawa I (1976) The Kidney, 3rd edn. 

Gaspari F, Perico N, Remuzzi G (1997) Measurement of glomerular filtration rate. Kidney Int (Suppl.63) S151-S154... 

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. 

G12. Grubb, A., Simonsen, O., Sturfelt, G., Truedsson, L., and Thysell, H., Serum concentration of cystatin C, factor D and 02-microglobulin as a measure of glomerular filtration rate. Acta Med. Scand. 218(5), 499-503 (1985). 

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 ... 

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