Kidneys glomerular filtration, measurement

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 ... 

Hackstein N, Heckrodt J, Rau WS (2003) Measurement of single-kidney glomerular filtration rate using a contrast-enhanced dynamic gradient-echo sequence and the Rutland-Patlak plot technique. JMagn Reson Imaging 18 714-725... 

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. 

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). 

Most protein pharmaceuticals exhibit a short half-life—measured in minutes—and high clearance because they are smaller than 30kDa and are readily cleared by glomerular filtration in the kidneys. Some pharmacokinetic features of protein phar-... 

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... 

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. 

Bostom AG, Dworkin LD. Cystatin C measurement improved detection of mild decrements in glomerular filtration rate versus creatinine-based estimates. Am J Kidney Dis 2000 36 205-7. 

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