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Effect of long-acting somatostatin analog (SMS 201-995) on high glomerular filtration rate in insulin dependent diabetic patients.

Increased glomerular filtration rate (GFR) is considered to be a determinant factor in the pathogeny of diabetic nephropathy. In this study we analyzed the effect of a long-acting somatostatin analog (SMS 201-995) on high GFR in type I diabetes patients. Five subjects were involved in a cross-over double blind study. All the patients had a high GFR (205 +/- 18 ml/min/1.73 m2). They were randomly submitted to a 10-hour night i.v. infusion of SMS 201-995 at a rate of 8 g/min and placebo. GFR was measured using a blood 99mTc-DTPA decay curve during the last hour of infusion. After 10-hour SMS 201-995 treatment, no statistical change was observed in GFR. However, a slight decrease was noted in four of the five subjects (183.07 +/- 22.31 vs 202.83 +/- 13.23 ml/min/1.73 m2). GFR was higher only for the patient who presented with a mild hypoglycemic reaction during the infusion, which may increase glomerular filtration by itself. All the other parameters measured remained unchanged.

Adult↗

Foot process fusion and glomerular filtration rate in minimal change nephrotic syndrome.

Reduced glomerular filtration rate (GFR), not due to hypovolemia, has been reported in patients in the proteinuric phase of the minimal change nephrotic syndrome (MCNS). A group of children with MCNS was studied to investigate the possible relationship between the fusion of glomerular epithelial foot processes and the reduction in GFR. The degree of foot process fusion was estimated as the harmonic true mean of foot process width and the length density of epithelial slit pores as determined by quantitative electron microscopic stereology. In the patients investigated GFR ranged between 40 and 127 ml/min/1.73 m2 body surface area, the filtration fraction between 6.9 and 22.5%, and the serum albumin concentration between 14 and 46 g/liter. The mean foot process width, which varied between 330 and 870 nm, showed a close correlation with GFR (r = -0.859) and the filtration fraction (r = -0.812), as well as with the serum albumin concentration (r = -0.756). As expected, a reduction of epithelial slit pore length occurred concomitant with the broadening of the foot processes. These results agree with the hypothesis that the reduction in the total length of glomerular epithelial slit pores, due to the fusion of foot processes, results in a reduced glomerular capillary permeability to water and small solutes.

Adolescent↗

Increased glomerular filtration rate and adrenocortical function in obese women.

Glomerular filtration rate (GFR) was measured in 16 obese women aged 28-48 years (overweight 65-110 per cent) and compared to GFR in 16 non-obese women of the same age and height. None of the women had signs of nephrourological disorders. GFR was determined from the total 51 Cr-EDTA plasma clearance measured by a simplified single-injection technique. In the obese women GFR (median value 129.0 ml/min) was significantly (P less than 0.002) increased by 24.6 per cent. The urinary excretion rate of 17-ketogenic steroids was increased in nine out of 14 obese women, but no correlation with GFR could be demonstrated. GFR in the obese women showed a significant positive correlation with the plasma cortisol concentration (rs = 0.77; P less than 0.01) and with the urinary excretion rate of free cortisol (rs = 0.78; P less than 0.01). Whether the correlation between the plasma cortisol concentration and the increased GFR in obese women is causal needs further investigation.

17-Hydroxycorticosteroids↗

Are glomerular filtration rate estimations necessary before high dose methotrexate?

Glomerular filtration rates (GFR) were estimated in 168 children (227 estimates) before treatment for haematological malignancies with high dose, intravenous methotrexate. Clinical management was altered on the basis of GFR in only two cases, both of whom had tumour lysis syndrome. Routine estimations of GFR do not contribute to management.

Antimetabolites, Antineoplastic↗

[Study of the clinical factors associated with glomerular filtration rate].

OBJECTIVE: To investigate the relationship between glomerular filtration rate(GFR) and possible involved clinical factors and to offer an basis for building measurement GFR by the calculation method. METHODS: GFR from 46 cases of normal renal function group and 52 cases of renal insufficient group were determined by using clearance of 99mTc-DTPA, serum creatinine(SCr), urea nitrogen, uric, potassium, sodium, calcium and hemoglobin were determined. Simultaneously, heart rate, urine specific gravity, 24 hours urine protein quantum, average artery pressure, weight index and body surface area were determined. Age, isotope dose for determining GFR were recorded. The simple correlation analysis between GFR in every group and the difference primitive diseases and clinical factors mentioned above were performed and the multiple correlation analysis between every clinical factors mentioned above that had significantly correlation between GFR and GFR were performed as well. RESULTS: GFR in normal renal function group, insufficient group and the difference primitive diseases had significantly negative correlation with SCr, while the correlations between GFR and other clinical factors were different. CONCLUSION: SCr is the ideal index for GFR for renal insufficient patients due to different primitive diseases and patients with normal renal function.

Adolescent↗

Measurement of the plasma clearance of urographic contrast media for the determination of glomerular filtration rate.

Further experience with a new method to determine glomerular filtration rate is presented. The method depends on measurement by an x-ray fluorescence technique of the plasma disappearance of the injected iodine in standard nonionic radiographic contrast media used during excretory urography. The results of comparison of contrast clearance with 99m technetium-diethylenetriaminepentaacetic acid clearance in 33 cases showed excellent agreement with a correlation coefficient of 0.95. Reproducibility of the contrast clearance method was confirmed by repeated examination of 10 plasma samples at weekly intervals for 6 weeks, the results of which showed no significant differences. The contrast clearance technique for the measurement of glomerular filtration rate during excretory urography is simple, quick and accurate, and merits further development.

Adult↗

Effects of an oral protein load on glomerular filtration rate in healthy controls and nephrotic patients.

Glomerular filtration rate (GFR), effective renal plasma flow (ERPF) and humoral factors were simultaneously examined before and after a 50-gram oral protein load in 12 healthy controls and 12 nephrotic patients. The protein load led to rises in GFR with unchanged filtration fraction in both groups although the rate of increase in GFR was greater in the former. The levels of blood urea nitrogen, serum osmotic pressure, plasma glucagon and serum insulin, but not plasma angiotensin II, were significantly elevated following the protein load. The increase in GFR after the protein load appears to be mainly caused by increased ERPF and afferent arteriolar vasodilation.

Administration, Oral↗

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↗

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↗

Correlation between serum creatinine, creatinine clearance, the calculated creatinine clearance and the glomerular filtration rate in heart transplant patients.

Assessment of glomerular filtration rate (GFR) in heart transplant (HTx) patients is based on serum creatinine (sCr), the endogenous creatinine clearance (C(Cr)) and radionuclide GFR (rGFR); however, the latter is expensive and time consuming. We reviewed the data of 32 adult HTx patients to determine the correlation between sCr, C(Cr), the calculated C(Cr) (Calc.C(Cr); based on gender, age, weight and sCr) and rGFR in long-term (>1 year) HTx patients receiving calcineurin inhibitors. The Calc.C(Cr) was found to have the best correlation with rGFR (r(2) = 0.65), followed by C(Cr) (r(2) = 0.53) and sCr (r(2) = 0.38). The use of Calc.C(Cr) to estimate GFR may be cost-effective in assessing renal function after HTx.

Aged↗

Serum beta-2-microglobulin estimation as an indicator of the glomerular filtration rate.

In 56 patients in whom the glomerular filtration rate (GFR) was estimated by the 51Cr-EDTA technique, serum creatinine and beta 2-microglobulin levels were also measured. In the 15 patients with a GFR of greater than or equal to 80 ml/min, both serum creatinine and beta 2-microglobulin levels were within the reference range. However, the beta 2-microglobulin level was elevated (greater than 2,3 mg/l) in all 41 patients with a GFR of less than 80 ml/min, while the serum creatinine level was increased (greater than 133 mumol/l) in only 35 patients. In the remaining 6 patients, the creatinine values ranged from 75 to 125 mumol/l. It would therefore seem that serum beta 2-microglobulin assay is a more sensitive test than creatinine assay for detecting impaired renal function.

Adult↗

Prediction of glomerular filtration rate from changes in serum creatinine.

The glomerular filtration rate (GFR) was estimated from serum creatinine concentration in patients in whom the individual relation between GFR and serum creatinine had been previously determined. 51Cr-EDTA plasma clearance was used as reference method for GFR. The relation between 51Cr-EDTA clearance and estimated GFR was determined from 340 investigations in 197 adult patients with a variety of infectious and internal diseases. The imprecision of estimated GFR was 46% (1 CV) at 20 ml/min, 23% at 45 ml/min, 20% at 75 ml/min and 18% at 110 ml/min. This poor precision was probably due to the fact that many patients with acute infectious diseases, congestive heart failure, diabetes mellitus, etc., have an unstable renal function and therefore their creatinine distribution is not under steady state. This must always be considered when serum creatinine is used to estimate GFR.

Chromium Radioisotopes↗

Determination of glomerular filtration rate using iohexol clearance and capillary sampling.

Glomerular filtration rate can be conveniently quantified by monitoring the plasma clearance of iohexol. In this study we have evaluated the possibility of further simplifying the investigation by using capillary sampling. Eight women and two men were given a single injection of iohexol (5 ml Omnipaque). Three to 4 h after the injection plasma and capillary samples were taken. Iohexol concentrations in whole blood and in plasma were measured by high-performance liquid chromatography after precipitation with perchloric acid. Iohexol in blood was quantitatively distributed to the plasma compartment. Plasma concentrations of iohexol calculated from the capillary blood concentration and erythrocyte volume fraction were in good agreement with actual plasma concentrations (r = 0.98). The imprecision of iohexol determination in capillary samples was 3.5% (CV) and clearance measurements using venous and capillary sampling also agreed well.

Adult↗

Glomerular filtration rate in conscious unrestrained starlings under dehydration.

Glomerular filtration rate (GFR) was measured in conscious unrestrained starlings, Sturnis vulgaris. Alzet osmotic minipumps were inserted into the peritoneal cavity under lidocaine local anesthesia and served to infuse the GFR marker [14C]sodium ferrocyanide. GFR was measured in hydrated birds and again after a 24-h period of water deprivation. GFR in dehydrated birds was 1.15 +/- 0.09 ml.min-1.kg-1, significantly lower (P less than 0.001) than the 2.71 +/- 0.31 ml.min-1.kg-1 in fully hydrated animals. In addition, the GFR of the hydrated birds was significantly lower (P less than 0.01) than values of 4.43 +/- 0.24 ml.min-1.kg-1 measured in hydrated anesthetized birds during micropuncture studies. A 24-h period of water deprivation caused significant increases in plasma osmolality and concentration of sodium, chloride, and phosphate. The osmolality and concentrations of calcium, magnesium, and phosphate were significantly elevated in both cloacal urine supernatant and in ureteral urine of dehydrated birds. In both hydrated and dehydrated states, the concentration of magnesium, phosphate, potassium, and total osmolality were significantly higher in cloacal urine than in ureteral urine.

Animals↗

A general equation for estimating glomerular filtration rate from a single plasma sample.

OBJECTIVES: Glomerular filtration rate (GFR) may be estimated from a single plasma sample measurement using empirical equations. This method forms the basis of international guidelines on GFR measurement. New guidelines have recently been recommended by the British Nuclear Medicine Society (BNMS). These use the slope-intercept technique in which several samples are obtained. Quality control of measurement may be achieved by comparison with the individual single-sample values. This paper compares international guideline single-sample estimates of GFR with the new BNMS method and derives an improved general single-sample equation. METHODS: GFR measurements using Tc-DTPA were performed on 180 adults and 100 children using samples at approximately 2 h and 3 h and a further 45 adults with samples at 2, 3 and 4 h. The two-sample values obtained using the BNMS guideline method were compared to one-sample estimates obtained using (1) international guidelines and (2) a new equation derived from the data. The new equation was evaluated in a further 145 subjects. RESULTS: The international guidelines technique had systematic differences between the one-sample and two-sample estimates of GFR. The new equation had minimal systematic error and reduced random error (standard error of the estimate 4.5 ml . min per 1.73 m). CONCLUSIONS: There were significant differences between GFR values obtained using the international guidelines single-sample method and the slope-intercept method described in the BNMS guidelines. The new equation described in this paper gave considerably improved agreement and is recommended if single-sample estimates are to be used as quality control for BNMS guideline measurements.

Adult↗

A simple method for the estimation of glomerular filtration rate.

A simple method is presented for indirect estimation of the glomerular filtration rate from two venous blood samples, drawn after a single injection of a small dose of [125I]sodium iothalamate (10 muCi). The method does not require exact dosage, as the first sample, taken a few minutes (t = 5 min) after injection, is used to normalize the value of the second sample, which should be taken in between 2-4 h after injection. The glomerular filtration rate, as measured by standard inulin clearance, may then be predicted from the logarithm of the normalized value and linear regression formulas with a standard error of estimate of the order 1-2 ml/min/1.73 m2. The slope-intercept method for direct estimation of glomerular filtration rate is also evaluated and found to significantly underestimate standard inulin clearance. The normalized 'single-point' method is concluded to be superior to the slope-intercept method and more sophisticated methods using curve fitting technique, with regard to predictive force and clinical applicability.

Adult↗

A comparison of the plasma disappearance of iohexol and 99mTc-DTPA for the measurement of glomerular filtration rate (GFR) in diabetes.

BACKGROUND: Changes in glomerular filtration rate (GFR) provide a valuable indicator of the progression of diabetic nephropathy. GFR is most commonly measured by the plasma clearance of radioisotopes, however, use of iohexol, a non-ionic radiocontrast medium, is a recently described alternative and has shown good agreement with inulin clearance. A one-compartment model is used for calculating GFR in most Australian centres but a two-compartment model is more accurate. AIMS: To set up a non-radioisotopic method for assessment of GFR using iohexol, and to compare this with the currently used 99mTc-diethylene-triamine-penta-acetic acid (DTPA) method. Secondly, to compare GFR results using an unmodified one-compartment model with a one-compartment model subjected to the Brochner-Mortensen modification. METHODS: Twenty-one patients with diabetes had assessment of GFR with simultaneous measurements of 99mTc-DTPA and iohexol plasma clearance. Plasma clearance was determined by the slope intercept method and then modified according to the Brochner-Mortensen equation. Plasma iohexol concentrations were determined by capillary electrophoresis. RESULTS: There was no significant difference between iohexol and 99mTc-DTPA derived GFR values, difference 4.3+/-7.7 mL/minute (mean+/-SD). This was despite 99mTc-DTPA protein binding demonstrated in the range of 5-10%. Comparison of GFR results using an unmodified one-compartment model with a Brochner-Mortensen corrected one-compartment model showed higher GFR values with the former, in the range of 20-30% for GFR values > 100 mL/minute. CONCLUSION: Iohexol provides an efficient alternative to radioisotopic methods for serial measurement of GFR in diabetic patients with hyperfiltration, incipient and overt nephropathy. A one-compartment model with its inherent overestimation of GFR should be replaced by the Brochner-Mortensen modified one-compartment model.

Adult↗

The glomerular filtration rate of isogeneically transplanted rat kidneys.

The glomerular filtration rate (GFR) was determined in rats with an isogeneic kidney transplant and compared with that of unilaterally nephrectomized rats. Experiments were carried out in adult rats, 3 months of age, weighing approximately 300 g, as well as in juvenile rats, 6 to 8 weeks of age, weighing approximately 170 g. All donor kidneys were taken from adult rats. The GFR was measured regularly, using a chromium 51-EDTA clearance technique which permitted repeated measurements to be taken in the same animals, during a 15-week followup period. After unilateral nephrectomy the GFR per 100 g body weight (BW) increased compared with that of a single normal kidney. Adult transplant recipients had a GFR per 100 g BW of about 80% of that of unilaterally nephrectomized rats. There was no statistical difference in the GFR when comparing adult recipients of either a normal or a hyperfunctional kidney. When isografts were transplanted to juvenile recipients, there was an initial decrease in the absolute GFR compared with the donor value in the case of a normal adult donor kidney. This decrease was even more pronounced when a hyperfunctioning kidney was transplanted to a juvenile recipient. However, when related to BW the GFR was, as in the adult recipients, about 80% of that of unilaterally nephrectomized juvenile rats. During the followup period the systolic blood pressure was measured regularly by tail plethysmography, in order to detect any blood pressure elevations, which are a frequent complication in adult and pediatric human renal transplantation. However, no hypertension was observed after isogeneic kidney transplantation in the various groups. These results show that the GFR of isogeneically transplanted rat kidneys amounts to about 80% of the maximally attainable level. Isogeneic transplantation of an adult kidney to a juvenile recipient results in a rapid adaptation of the GFR to the smaller size of the body and does not cause an increase in blood pressure.

Age Factors↗