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At least 19 recordsLinked to original sources
PubMed1992

[Key note comment on the determination of glomerular filtration rate].

Glomerular filtration rate (GRF) is the most fundamental renal function. Determination of GFR is the most important examination in clinical nephrology. Cin is accepted as the gold standard of GFR, but, continuous infusion and the determination method of inulin (method of anthrone) are very troublesome. Interference of glucose in the serum and urine of patients with diabetes mellitus on the determination of inulin should be avoided. Ccr is widely used in the clinical field. Recently, the dynamics of creatinine in the body have been clarified. Variation of pool, generation rate, extrarenal excretion and tubular excretion of creatinine are found to change daily in the patient. Additionally, classical Jaffé's reaction involves non creatinine chromogen particularly in the serum. Though Jaffé's reaction with kinetic analysis improves the reliability of this reaction, the result is still unsatisfactory. There are several methods of enzyme assay are now using an autoanalyser, but, if we use many enzymes and reagents, the reliability of this method could not exceed that of Jaffé's method. Recently, HPLC is recommended as the standard method. 24-hr urine collection is also troublesome in the measurement of Ccr. I have found a good correlation between the estimated Ccr using Cockcroft and Gault's formula and Cin. Such prediction using serum creatinine concentration and few parameters should be developed. Radiolabelled agents have been widely used for the determination of GFR. However, in Japan, the methods of clearance of non radiolabelled contrast agents should be developed. Furthermore, a physical determination of GFR is necessary. In this workshop, these issues will be discussed by each speaker.

Animals↗
PubMed1976

Influence of ureteral catheter size on urinary flow rate and glomerular filtration rate in the rat.

The influence of ureteral catheter diameter on renal function was studied in rats during different diuretic states. Urinary flow rate and glomerular filtration rate were measured on each rat using ureteral catheters of two different internal diameters. In non-diuretic rats, urinary flow rate and glomerular filtration rate did not change according to the catheter diameter. In diuretic rats, urinary flow rate was from 40 to 70% lower with the smaller catheter. Differences became more marked as urinary flow rate increased. Glomerular filtration rates were about 20% lower when measured with small catheters. These results clearly demonstrate that the use of small diameter ureteral catheters during diuretic states leads to a decrease in glomerular filtration rate and urinary flow rate. The results also emphasize the importance of using large diameter catheters during such experimental conditions.

Animals↗
PubMed1992

Evaluation of a single injection of 99mTc-labeled diethylenetriaminepentaacetic acid for measuring glomerular filtration rate in horses.

Glomerular filtration rate (GFR) was measured in 12 clinically normal horses, using the standard inulin clearance method, and values were compared with values for 2 methods, using a single rapid IV injection of 99mTc-labeled diethylenetriaminepentaacetic acid (99mTc-DTPA). The first 99mTc-DTPA method used a 2-compartment model to calculate GFR blood clearance of the tracer. The second method used sequential digital gamma camera images of the kidneys to determine fractional accumulation of the total dose of the tracer in the kidneys (percentage of injected dose, gamma camera) from 0 to 10 minutes after radionuclide administration. Linear correlation among the 3 methods was determined. Mean (+/- SD) GFR, using the inulin clearance method, was 154.67 +/- 42.28 ml/min/100 kg of body weight. Mean GFR, using the 2-compartment blood clearance curve, was 146.92 +/- 27.49 ml/min/100 kg. Mean GFR, using percentage of injected dose (gamma camera method) was 154.7 +/- 22.00 ml/min/100 kg. The percentage of injected dose (gamma camera method) did not correlate significantly to the inulin clearance results. However, a significant (r = 0.666, P less than 0.018) correlation was observed between the inulin method and the 99mTc-DTPA blood clearance method. Significant (P less than 0.0001) difference also was observed in the split function of the equine kidneys, with GFR of the right kidney contributing 60.1 +/- 9.12% of the total function, as determined by 99mTc-DTPA gamma camera imaging. Because the 99mTc-DTPA blood clearance method does not require urine collection, it may be a more practical procedure to measure GFR in the horse.

Animals↗
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↗
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↗
PubMed1978

Determination of glomerular filtration rate in advanced renal insufficiency.

The glomerular filtration rate (GFR) has been determined in 17 patients with advanced renal insufficiency (GFR less than 15 ml/min) by different clearance techniques using creatinine, inulin and 51Cr-EDTA as filtration markers. With renal inulin clearance as reference method for GFR, endogenous renal creatinine clearance overestimated GFR by an average of 30%. Renal clearance of 51Cr-EDTA and inulin were closely correlated and thus 51Cr-EDTA is a suitable GFR marker even at low filtration rates. However, it was found that the plasma clearance of 51Cr-EDTA overestimated the GFR often by more than 100% in the range 2.6--11.2 ml/min. Renal clearance measured during 24 h was lower than 4 h renal clearance with the patient well hydrated and resting in bed. It is concluded that the precise measurement of low glomerular filtration rates requires the use of renal clearance techniques. Four-hour 51Cr-EDTA renal clearance is a suitable method for measuring and following the development of renal function in advanced renal insufficiency.

Adult↗
PubMed1992

Practical approach for determining glomerular filtration rate by single-injection inulin clearance.

We compared the glomerular filtration rate as measured by a single-injection inulin clearance with that measured by a standard isotope method with 99mTc-labeled diethylenetriaminopentaacetic acid in 21 subjects with glomerular filtration rates greater than 35 mL/min. After a bolus injection of 5 g of inulin, blood samples were taken 20, 45, 90, 120, 145, 180, and 240 min afterwards. Inulin was measured by optimized chemical or enzymatic methods of high analytical sensitivity to determine inulin at low concentrations. We used the one-compartment model and inulin concentrations measured at two sampling times to calculate the glomerular filtration rate from the data of the disappearance curve of inulin. Inulin concentrations at 20 and 240 min after injection of the inulin bolus were suited to estimate glomerular filtration rate by this procedure, resulting in values (y) comparable with those obtained by isotope technique (x). The relationship to the isotope technique was characterized by the equation y = +4.80 mL/min + 0.92x (r = 0.97). The single-injection inulin clearance determination can detect a decrease of glomerular filtration rate at the beginning of kidney damage, given that our study included subjects with glomerular filtration rates greater than 35 mL/min. We conclude that the glomerular filtration rate can be determined by analyzing only two blood samples after a bolus injection of inulin.

Adult↗
PubMedDate not supplied

Does increased glomerular filtration rate or disturbed tubular function early in the course of childhood type 1 diabetes predict the development of nephropathy?

To clarify whether glomerular hyperfiltration or disturbances in renal tubular function may be early markers of the later development of nephropathy a follow-up study was performed in 34 young Type 1 diabetic patients, who had originally been investigated 12 years previously. The initial median age was 14 (range 7-18) years and median diabetes duration 7 (2-14) years. At initial examination only one of the 34 diabetic patients exhibited increased urinary albumin excretion rate. The median glomerular filtration rate was increased (136 vs 107 ml min-1 1.73 m-2; p less than 0.0001) and median threshold concentration of phosphate per litre of glomerular filtrate was decreased (1.27 vs 1.76 mmol l-1; p less than 0.0001) in the diabetic group as compared to that of 28 healthy children. At follow-up 17 patients showed increased urinary albumin excretion rate and the median glomerular filtration rate in this group was significantly lower than that of 17 patients with normal urinary albumin excretion rate (108 vs 125 ml min-1 1.73 m-2; p less than 0.05). However, no relationships were found between the increased urinary albumin excretion (incipient and/or overt diabetic nephropathy) at follow-up to either the initial glomerular filtration rate (134 vs 137 ml min-1 1.73 m-2; p greater than 0.05) or to renal tubular function assessed from urinary excretion rate of beta 2-microglobulin (0.059 vs 0.069 microgram min-1; p greater than 0.05) and the renal threshold concentration of phosphate per litre of glomerular filtrate (1.29 vs 1.22 mmol l-1; p greater than 0.05).

Adolescent↗
PubMed1992

Expressing glomerular filtration rate in terms of extracellular fluid volume.

Glomerular filtration rate (GFR) is routinely calculated from the second exponential of the bi-exponential plasma clearance of filtration markers such as Cr-51 EDTA and Tc-99m DTPA. By ignoring the first exponential, true GFR is overestimated, an error which increases with increasing GFR. The rate constant, lambda 2, of the second exponential represents the rate at which glomerular filtration 'turns over' the extracellular fluid (ECF) and so closely approximates GFR/ECF volume. Again, the error in the estimation of this ratio increases with increasing GFR, although in this case it underestimates the true ratio. Expressing GFR in terms of ECF volume, rather than in terms of body surface area, offers considerable technical and physiological advantages. The relationship between GFR/ECF volume and lambda 2, over a wide range of renal function, expressed as a second order polynomial, was GFR/ECF volume = -0.093 + 1.06 lambda 2 + 0.009 lambda 2(2) ml.min-1.l-1. The corresponding relationship between 'true' GFR (C1) and approximate GFR (i.e. based only on the second exponential--C2) was C1 = -0.58 + 1.012C2 -0.0011 C2(2) ml.min-1 For any level of renal function, the error in GFR/ECF volume, expressed as lambda 2, is less than the error in GFR expressed as C2. Since GFR may change as a direct result of a change in ECF volume, it is physiologically more relevant, and technically very much easier, to express GFR in terms of ECF volume rather than body surface area.

Adult↗
PubMed1975

Glomerular filtration rate in sick elderly inpatients.

The glomerular filtration rate was measured in the sick elderly patients using the single shot 51Cr EDTA method. As would be expected, such patients have worse renal function than the fit elderly. The filtration rate can be usefully predicted from either blood urea or serum creatinine, but a superior prediction is obtained when these factors are combined using a formula derived from multiple regression analysis.

Aged↗
PubMed1992

Creatinine clearance during cimetidine administration for measurement of glomerular filtration rate.

Creatinine clearance inaccurately estimates true glomerular filtration rate (GFR) because of tubular secretion of creatinine. We studied the ability of oral cimetidine, a blocker of tubular creatinine secretion, to improve the accuracy of measuring creatinine clearance. Clearances of inulin and endogenous creatinine were simultaneously measured in 16 patients with renal disease before administration of cimetidine and during 8 successive 3 h clearance periods with cimetidine 400 mg as priming dose followed by 200 mg every 3 h. At baseline, creatinine relative to inulin clearance (ClC/Cll) ranged from 1.14 to 2.27. With cimetidine, ClC/Cll approached unity in 8 patients (mean 1.02 [SD 0.03]), but considerably exceeded unity in 8 others (1.33 [0.14]). Plasma cimetidine/creatinine ratio was smaller in this second group, due to significantly higher renal clearance of cimetidine (333 [136] vs 165 [89] ml/min, p = 0.01). In a further study, cimetidine dose and, consequently plasma cimetidine concentration, was increased in 6 additional patients who had incomplete inhibited previously. This increased dose completely inhibited tubular creatinine secretion in the third until the sixth hour, so that creatinine clearance equalled GFR. Provided an adequate dose of cimetidine is given, 24 h creatinine clearance during administration of drug measures GFR accurately in patients with renal disease. However, because of the maximum daily dose of cimetidine that is advised, short clearance times (3 h) are recommended.

Adolescent↗
PubMed2010

Common charge-shift mutation Glu65Lys in K+ channel β₁-Subunit KCNMB1: pleiotropic consequences for glomerular filtration rate and progressive renal disease.

BACKGROUND: Glomerular filtration rate (GFR) is a heritable trait, and hyperfiltration (GFR increment in remnant nephrons) may accelerate renal functional decline in chronic kidney disease (CKD). Mesangial and vascular smooth myocytes control GFR by contraction, dependent on voltage-gated Ca(2+) influx, which is controlled by the regulatory β₁-subunit (KCNMB1) of large-conductance heteromeric K+ ('BK') channels. KCNMB1 gain-of-function variant Glu65Lys results in generalized vasorelaxation and thus protection against systemic hypertension. Here we asked whether the Glu65Lys variant influences GFR, in the basal state or during progressive renal decline. METHODS: We explored Glu65Lys effects on GFR in three populations spanning two ethnicities and two diseases (hypertension and nephrosclerosis). GFR was either estimated (eGFR from serum creatinine) or directly measured (iothalamate clearance). RESULTS: The 65Lys variant was relatively common, occurring on ∼5-10% of chromosomes in different biogeographic ancestry groups, and 65Lys carriers exhibited higher eGFR in two primary care populations: extreme BP values in Kaiser clinics (p = 0.029, accounting for ∼0.2% of trait variance), or treated hypertensives in VA clinics (p = 0.017, accounting for ∼0.9% of trait variance). In blacks with progressive renal disease (NIDDK AASK), 65Lys carriers displayed a steeper slope in GFR chronic decline (p = 0.030, accounting for ∼0.4% of trait variance), and Glu65Lys genotype also predicted time of onset of renal failure (log rank p = 0.019). CONCLUSIONS: Common KCNMB1 gain-of-function variant Glu65Lys influences GFR, and 65Lys carriers exhibit not only elevated baseline GFR, but also more rapid GFR decline (and consequent development of renal failure) in CKD. The results suggest that profiling patients at Glu65Lys can assist in gauging renal prognosis as well as selection of rational therapy in hypertension with progressive renal disease.

Black or African American↗
PubMed1977

Lack of dependence of urine PCO2 upon reduction of glomerular filtration rate in alkalotic dogs.

1. The PCO2 gradient between alkaline urine and arterial blood (U-B PCO2) is thought to depend primarily on distal hydrogen ion secretion. However, other variables affecting the U-B PCO2 include the urine flow rate, the urinary bicarbonate and phosphate excretion rates and the glomerular filtration rate. 2. In order to evaluate the effects of acute changes in these factors on the U-B PCO2, bicarbonate-loaded dogs with maximal U-B PCO2 values were subjected to either acute unilateral elevations of ureteral pressure or hypotension caused by nitroprusside infusion. The results demonstrate that acute reduction in the glomerular filtration rate does not cause a decrease in the U-B PCO2 as long as the urinary concentrations of phosphate and bicarbonate do not decline. 3. Urinary concentrations of phosphate and bicarbonate appeared more important than their excretion rates in the maintenance of elevated U-B PCO2 values.

Alkalosis↗
PubMed1975

Increased kidney size and glomerular filtration rate in untreated juvenile diabetes: normalization by insulin-treatment.

Glomerular filtration rate (GFR), renal plasma flow (RPF) and roentigenographic kiendy size were measured in six newly diagnosed male diabetics with a mean age of 25 years. Glomerular filtration rate was elevated before treatment to the same extent as found previously. A significant fall in both kidney size and glomerular filtration rate was found after treatment with insulin for 3 months. These results support further the concept that there is a basal connection between enlarged kidneys and the elevated GFR of early diabetes.

Diabetes Mellitus, Type 1↗
PubMed1992

Increased glomerular filtration rate as a predictor of diabetic nephropathy--an 8-year prospective study.

The objective was to study the natural history and the predictive value of glomerular filtration rate, albumin excretion rate, blood pressure, and hemoglobin A1c for diabetic nephropathy. A cohort of 75 type-1 diabetic adolescents with a diabetes duration of 8 years was studied. Thirty-one females, 33 males, mean age 16.9 +/- 0.3 (SEM) participated in the follow-up study. Glomerular filtration rate, albumin excretion rate, blood pressure, and hemoglobin A1c were measured every second year during 8 years to determine the predictive value of glomerular filtration rate for future nephropathy. Initial differences and patterns of changes in glomerular filtration rate, albumin excretion rate, and hemoglobin A1c were examined in patients who did (group 1) and did not (group 2) develop incipient or overt nephropathy. Five of 64 patients developed overt nephropathy. They had an initial glomerular filtration rate of greater than 125 ml/min/1.73 m2. Fifteen of 53 initially normoalbuminuric patients developed incipient and three of 53 overt nephropathy. Age, age at onset, diabetes duration, initial albumin excretion rate, initial blood pressure, and hemoglobin A1c were similar in groups 1 and 2. Glomerular filtration rate was initially higher in group 1 than in group 2 (P = 0.01). The positive predictive value for combined incipient and overt nephropathy of an initial glomerular filtration rate greater than 125 ml/min was 53%. The negative predictive value of glomerular filtration rate less than 125 ml/min was 95%. In initially normoalbuminuric patients multiple regression revealed initial glomerular filtration rate as the only significant independent predictor for nephropathy when also corrected for hemoglobin A1c (P = 0.04).(ABSTRACT TRUNCATED AT 250 WORDS)

Albuminuria↗
PubMed1977

Noninvasive determination of glomerular filtration rate using x-ray fluorescence.

Accurate glomerular filtration rates (GFR) can be calculated based on the infusion of small amounts of nonradioactive iothalamate and collection of plasma samples for assay by x-ray fluorescence. This innovation permits frequent clearance determinations in patients without the hazard of repeated radiation exposure and without the necessity of catheterization of the bladder for urine samples. Thus, the technique becomes feasible in children, transplant patients, and other needing accurate and frequent GFR determinations.

Animals↗
PubMed1979

Postnatal development of renal function in piglets: glomerular filtration rate, clearance of PAH and PAH extraction.

Glomerular filtration rate (GFR), estimated as clearance of inulin, and clearance of p-aminohippuric acid (CPAH) were measured in 32 unanaesthetized piglets 1--62 days of age. During this period of time, GFR increased from 0.27 to 0.59 ml/min/g kidney and CPAH increased from 1.02 to 1.72 ml/min/g kidney. At 8 weeks of age, GFR and CPAH equaled adult values. In addition, renal PAH extraction (EPAH) was estimated in 12 anaesthetized piglets aged 1--79 days. EPAH increased from 0.75 at birth to 0.86 (adult value) at 3 weeks of age. The result shows a postnatal increase in renal functions in piglets, but the development from birth to adult level was less pronounced than seen in other animal species.

Animals↗