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Results for “glomerular filtration rate”

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PubMed1977

A single-injection method for measuring glomerular filtration rate.

A method for estimating glomerular filtration rate (GFR) has been developed that is based on an analysis of the total area under the plasma radioactivity-time curve after a single intravenous injection of [125I]iothalamate. Glomerular filtration rates obtained by this method (method A) and those obtained with two widely used single-injection techniques, the slope-intercept method (method B), and the two-compartment method (method C), were compared with GFRs obtained by standard inulin clearance techniques in 14 dogs. Method B consistently over. estimated inulin clearances more than 30%. Method C also overestimated inulin clearance considerably in dogs with an increased extracellular fluid volume, but was fairly reliable in normal dogs. Glomerular filtration rates obtained by the new method (method A) were in excellent agreement with inulin clearances in all dogs, regardless of the state of body hydration. The mean inulin clearance for all 14 experiments was 72.7+/-6.0 SE ml/min, while GFRs obtained by method A averaged 75.1+/-6.0 ml/min. The data from this study suggest that method A is a reliable means for estimating GFR that is especially useful in chronic experiments.

Animals↗

PubMed1984

The effect of intravenous contrast medium on glomerular filtration rate.

The changes in glomerular filtration rate (GFR) after intravenous contrast medium have been investigated with three contrast media of differing osmolality (monomer, dimer and non-ionic agent) in antidiuretic dogs with three different basal solute excretion rates. A transient increase in GFR after contrast medium was attributed to the wash-out of medullary creatinine at the onset of diuresis. The subsequent fall in GFR was greatest with the contrast media of higher osmolality and in those dogs without an underlying solute diuresis. With the monomer, the decrease in GFR produced a significant decrease in the amount of contrast medium excreted in the first few minutes after contrast injection. It is suggested that an important factor in the decrease in GFR is the rise in pressure in the renal tubules at the start of a diuresis, before they have had time to dilate. An underlying solute diuresis is considered to protect against the fall in GFR because tubular dilatation has already occurred in response to the basal solute load. The decrease in blood pressure during and after contrast medium injection did not correlate with the fall in GFR.

Animals↗

PubMed2003

[Evaluation of glomerular filtration rate in clinical practice].

Glomerular filtration rate (GFR) is the most frequently used parameter to evaluate the renal function. GFR may be estimated with serum creatinine, creatinine clearance based on 24 hours urine collection or Cockcroft formula. All these methods have bias. Other approaches have thus been proposed. The limitations and advantages of isotopic methods and recent mathematical approaches (MDRD formula) are reviewed.

Chromium Radioisotopes↗

PubMed1981

Reference values for 51Cr-EDTA clearance as a measure of glomerular filtration rate.

Reference values for glomerular filtration rate (GFR) were defined using eight reports including epidemiological studies and studies in kidney donors. Studies using both inulin and 51Cr-EDTA were included. GFR decreased with age, by 4 ml/min decade below the age of 50, and 10 ml/min decade above 50 years of age. No sex difference was found. +/- 2 SD was equal to 25 ml/min at all ages. Based on these findings a nomogram for GFR is presented. Emphasis is given to the use of plasma clearance of 51Cr-EDTA estimated with single injection technique as the new reference method for GFR measurement.

Adolescent↗

PubMed1991

Comparison of a single-injection technique and inulin clearance for determining glomerular filtration rate in the sheep.

Glomerular filtration rate (GFR) was assessed over a 2 h period by the clearance of inulin (Cin) and in the subsequent 2 h period by a single-injection technique using radiolabelled sodium iothalamate (Ciot) or chromium-EDTA (CEDTA). Regression analysis yielded a significant correlation (P less than 0.05) between the standard clearance technique and the single-injection method, with the relationship Ciot = -10.67 + 1.25Cin with a significant correlation coefficient of r = 0.71 (P less than 0.02). There was better agreement between clearance values of inulin measured on successive days than between values determined by the single-injection technique on successive days. Cin remains the method of choice in sheep.

Animals↗

PubMed1976

[Glomerular filtration rate in newborn infants].

Glomerular filtration rate (GFR) was studied in twelve newborns by means of a single inulin injection. Five of them were of 34 to 35 weeks of gestation (preterm group); the other seven were born between 38 to 41 weeks of pregnancy (term group). Age at time of study varied between three to nine days; weights were normal for gestational age and there was no history of abnormal pregnancy. Inulin was determined according to Schriner's technic and GFR was obtained by Sapirstein's method. GFR was 1.48 +/- 0.70 ml/min in the preterm and 2.40 +/- 0.53 ml/min in the term group less than0.05). However, when body surface was taken into consideration, in the former GFR was 17.28 +/- 8.06 ml/min/1.73 m2 and in the term group 20.64 +/- 4.46 ml/min/1.73 m2; in this way, no significant difference was shown.

Body Weight↗

PubMedDate not supplied

Single-injection inulin clearance--a simple method for measuring glomerular filtration rate in dogs.

The glomerular filtration rates (GFR) of 93 dogs of different breeds with a broad range of bodyweight were determined using an inulin single-injection method. Fifty-two dogs were used as controls, 21 dogs had suspected renal disease but serum creatinine in the normal range, and 20 dogs had elevated serum creatinine levels and a low urine specific gravity due to renal disease. Inulin was injected intravenously at a dosage of 100 mg kg(-1) bodyweight or 3000 mg m(-2) body surface. Blood samples were taken before and three, 20, 40, 80 and 120 minutes after injection. The total clearance was calculated from the decrease in the serum concentration of inulin using a two-compartment model. The range of GFR values was 83.5-144.3 ml min(-1) m(-2) in control dogs, 60.2-96.7 ml min(-1) m(-2) in dogs with suspected renal disease, 50.0-76.2 ml min(-1) m(-2) in dogs with suspected renal disease and polyuria/polydipsia, and 16.3-63.0 ml min(-1) m(-2) in dogs with azotaemic renal disease. The study indicates that single-injection inulin clearance is a cheap and simple tool for GFR measurements in small animal practice.

Animals↗

PubMed2006

Validation of child serum creatinine-based prediction equations for glomerular filtration rate.

Equations for estimating glomerular filtration rate (GFR) are vital in caring for patients with renal disease and the current standard, the Schwartz formula, lacks precision. We evaluated several child serum creatinine-based GFR prediction equations. Subjects aged 2-21 years who underwent iothalamate GFR (IoGFR) testing between 1999 and 2004 were studied retrospectively. GFR was estimated using: (1) Schwartz formula (SchwartzGFR), using a local k value; (2) Schwartz model (SchwartzMod) using regression-derived coefficients; (3) Leger GFR (LegerGFR) using original coefficients; and (4) Leger model (LegerMod) using regression-derived coefficients. Bias, precision, and diagnostic characteristics were evaluated. There were 195 subjects [61% male; mean (SD) age 12.4 (4.5) years; mean (SD) IoGFR 78.9 (33.4) ml/min per 1.73 m(2)]. Only the LegerGFR overestimated IoGFR (5.5 ml/min per 1.73 m(2)). Precision for all formulae was poor (95% limits of agreement approximately -40 to 40 ml/min per 1.73 m(2)), but >or=72% of estimates were within 30% of IoGFR. Sensitivities for detecting IoGFR <30 and 90 ml/min per 1.73 m(2) were highest using the SchwartzGFR (80%) and SchwartzMod (90%), respectively. The LegerGFR was most specific. Using local coefficients, the Schwartz and Leger models were imprecise estimates of GFR, but the Schwartz model was most unbiased and sensitive. Future research should derive more precise equations for GFR in children.

Adolescent↗

PubMed1980

A strong correlation between glomerular filtration rate and filtration surface in diabetic kidney hyperfunction.

The direct relationship between glomerular filtration surface and glomerulaf filtration rate was studied in a group of eight short term, young diabetics exhibiting a 50 per cent elevated glomerular filtration rate with a 2-fold variation within the group. A close correlation was obtained between glomerular filtration surface and glomerular filtration rate, r = 0.8. This supports the idea that the increase in glomerular capillary surface may be a main factor in diabetic kidney hyperfunction. The possible long term implications of the functional and morphologic abnormalities are discussed.

Adult↗

PubMed2002

Effect of exogenous and endogenous angiotensin II on intrarenal distribution of glomerular filtration rate in rats.

Different changes in glomerular filtration rates (GFR) in deep and superficial glomeruli have been suggested to influence renal NaCl excretion and concentrating ability. Angiotensin II (AngII) has been implicated in such changes, but the experimental evidence has been conflicting, probably because of the methodological limitation of just one 'snapshot' measurement of local GFR per kidney. We have therefore studied the effect of AngII and AT(1)-receptor blockade on glomerular filtration in outer, middle and inner cortex (OC, MC and IC, respectively) in pentobarbitone-anaesthetised rats using the aprotinin (Ap) method, providing control and experimental measurements in the same kidney. Glomerular filtration rate per gram cortical tissue was measured based on 'free' glomerular filtration of Ap followed by complete tubular uptake and a 20 min sojourn in the proximal tubular cells before breakdown and incipient return to the plasma.(125)I-labelled Ap was injected I.V. to determine control Ap clearance, followed after 13 min by injection of AngII or the A1 type AngII receptor blocker losartan and 2 min thereafter by (131)I-labelled Ap to determine clearance in the experimental period. Tracer activity in frequent blood samples and in tissue samples allowed calculation of GFR in the two periods. Mean GFR control values were: 1.13 ml min(-1) in whole kidney and 1.44, 1.27 and 0.76 ml min(-1) per gram cortical tissue in OC, MC and IC, respectively. The most sensitive and comprehensive measure of altered GFR distribution is the ratio between the relative filtration change in inner versus that in outer cortex, F = (IC(E)/IC(C))/(OC(E)/OC(C)), where subscripts E and C stand for experimental and control, respectively. F values greater than 1.00 directly indicate and quantify a relatively greater increase of filtration rate in inner than in outer cortex. We found in salt-replete rats that at practically unchanged total GFR, intravenous and intra-arterial infusion of AngII increased F to 1.07 and 1.04 (P < 0.05) whereas losartan reduced F to 0.99. After pretreatment with the inhibitor of nitric oxide production L-NAME, losartan increased total GFR by 8 % and F fell to 0.95 (P < 0.05). In salt-depleted rats losartan reduced F to 0.95 (P < 0.05) at unchanged total GFR. All IC/OC changes induced by losartan were significantly different from that obtained by AngII infusions. We conclude that deep nephrons have higher postglomerular AngII tone and also higher AngII sensitivity than superficial nephrons. The better preserved GFR in deep cortex during AngII action may contribute towards maintaining the renal concentrating ability by providing NaCl for reabsorption by the ascending limb of the loop of Henle.

Angiotensin II↗

PubMed2003

Tubuloglomerular feedback and the control of glomerular filtration rate.

In every nephron the glomerular filtration rate is adapted to changes in the salt concentration of early distal tubular fluid through the mechanism of tubuloglomerular feedback. Recent studies indicate that adenosine and possibly ATP mediate this mechanism and demonstrate its role in glomerular hemodynamic alterations in the early diabetic kidney.

Animals↗

PubMedDate not supplied

Pharmacokinetic aspects of measurement of glomerular filtration rate in the dog: a review.

Glomerular filtration rate (GFR) is estimated by means of clearance, defined as the volume of plasma that has been cleared of a particular substance per unit time. Glomerular filtration rate may be estimated by measuring the renal clearance of a filtration marker using data from both urine and plasma or by plasma clearance using only plasma data. Several alternative pharmacokinetic models are used for the calculation of clearance using various filtration markers with slightly different pharmacokinetic properties. The purpose of this article is to discuss how the choice of marker and pharmacokinetic model may influence estimated GFR values and to elucidate commonly used methods and reported GFR values in the dog.

Animals↗

PubMedDate not supplied

Effect of diabetes mellitus on glomerular filtration rate in an urban hospital diabetic population.

Glomerular filtration rate (GFR) as assessed by endogenous creatinine clearance was studied in 46 male and 38 female patients with diabetes mellitus (DM). Of these, 44 patients had uncomplicated DM (Group I) whilst 40 patients had complicated DM (Group II). There were 20 insulin-dependent diabetes mellitus (IDDM) patients in Group I and 5 in Group II, and 24 non-insulin dependent diabetes mellitus (NIDDM) patients in Group I and 35 in Group II. In Group I, 6 IDDM and 4 NIDDM patients had supranormal glomerular filtration rate (creatinine clearance 125 ml/min) and in Group II 1 IDDM and 6 NIDDM patients had supranormal GFR. The presence of diabetic complications and the mode of therapy of the diabetic state did not significantly affect the glomerular filtration rate. This concludes that glomerular hyperfiltration occurred in both IDDM and NIDDM Nigerian patients.

Adolescent↗

PubMed1995

A simple method for measuring glomerular filtration rate in dogs.

A technique for measuring glomerular filtration rate (by six-sample plasma clearance) and extracellular fluid volume is described. The results obtained for glomerular filtration rat per extracellular fluid volume with a three blood sample technique are also presented. Concurrently with the blood sample techniques measuring plasma clearance, glomerular filtration rate per extracellular fluid volume was also measured using an external radiation detector and no blood samples. The validity of expressing glomerular filtration rate per extracellular fluid volume (rather than per body weight or surface area) and the clinical utility of the results obtained with the external radiation detector are discussed.

Animals↗

PubMed2001

Prediction equations to estimate glomerular filtration rate: an update.

The level of glomerular filtration rate can be estimated from the serum creatinine concentration and other easily measured patient variables from prediction equations developed using multivariable regression techniques. Recently, a new equation has been developed from the Modification of Diet in Renal Disease study, which is more accurate than other equations and more accurate than measurement of creatinine clearance. The authors recommend using prediction equations in clinical practice to estimate the level of glomerular filtration rate.

Forecasting↗

PubMed2001

[Cystatin C as a marker of glomerular filtration rate].

The assessment of the glomerular filtration rate (GFR) is the most commonly used test of renal function. Cystatin C, a cysteine protease inhibitor, which can be measured by light scattering immunoassay, possesses many of the attributes required of the ideal GFR marker. This paper reviews so far obtained results dealing with cystatin C measurement, reference intervals and its diagnostic significance in nephropathy. Although serum cystatin C can generally be recommended as a marker of GFR, especially to detect mild GFR reductions, further clinical studies should be performed to confirm the validate in renal transplants and cancer patients.

Biomarkers↗

PubMed1999

Clearance kinetics of solutes used to measure glomerular filtration rate.

Agents used to measure glomerular filtration rate (GFR) give a biexponential plasma disappearance curve on multiple peripheral venous sampling between 20 min and 4 h after intravenous injection. These two exponentials are generally regarded to represent equilibration of agent throughout the extracellular fluid (ECF) space and renal clearance, respectively. In seven subjects undergoing diagnostic arteriography, arterial and antecubital venous plasma samples were obtained up to 60 min in five and up to 120 min in two following simultaneous intravenous injection of 99Tcm-diethylene triamine pentaacetate (99Tcm-DTPA) and inulin. The count rate from 99Tcm was simultaneously recorded over the calf with a collimated scintillation probe in five subjects up to 60 min post-injection. The arterial and venous time-concentration curves were interpolated and subtracted to give a curve of the arterio-venous (A-V) concentration difference, which was then integrated. Arterial time-concentration curves display three exponentials, the first of which has the largest amplitude and disappears by about 20 min. The A-V concentration difference becomes zero at about the same time. The integral of the A-V concentration difference, which represents activity in the interstitial space of the forearm, has a time course consistent with the second compartment of a model of two compartments in series (the first being plasma) and a time course that is reciprocally similar to the first exponential of the triexponential arterial plasma curve. The curve externally recorded by scintillation probe has a shape consistent with a signal that is the composite of interstitial 99Tcm-DTPA and plasma 99Tcm-DTPA activities. The arterial plasma clearance curve of GFR agents is triexponential; the first exponential reflects equilibration of agent between plasma and the interstitial space of carcass tissue (mainly muscle and skin). The second exponential is minor compared with the first; it is not clear what it represents. The third exponential reflects renal clearance.

Adult↗

PubMed2000

Developments in the assessment of glomerular filtration rate.

The assessment of the glomerular filtration rate (GFR) is the most commonly used test of renal function. The accepted reference procedure employs an exogenous clearance marker whilst the most popular test is that of serum or plasma creatinine. All of these tests have limitations, although the surrogate endogenous markers are the most practical. Cystatin C, a low molecular weight protein which can be measured by light scattering immunoassay, possesses many of the attributes required of the ideal GFR marker. Data on reference ranges indicate that circulating cystatin C levels reflect the variation in GFR throughout life and the marker demonstrates a better correlation with the reference procedure than serum creatinine.

Biomarkers↗