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PubMed2001

Stimulation of apoptosis by two prebiotic chicory fructans in the rat colon.

Prebiotics, in particular the chicory derived beta(2-1) fructans, have been shown to exert cancer protective effects in animal models. The present study was carried out to determine the effects of two chicory fructans--oligofructose (RaftiloseP95; average degree of polymerization DP = 4) and long chain inulin (RaftilineHP; average DP = 25), on apoptosis and bacterial metabolism associated with carcinogenesis. Eighteen rats were fed a stock diet for one week. Three groups of six animals were then fed one of three diets: basal, basal with oligofructose (5%w/w) or basal with long chain inulin (5%w/w), for a three week period. All animals were then dosed with 1,2-dimethylhydrazine and killed 24 h later. The mean number of apoptotic cells per crypt was significantly higher in the colon of rats fed oligofructose (P = 0.049) and long chain inulin (P = 0.017) as compared to those fed the basal diet alone. This suggests that oligofructose as well as the long chain inulin exert protective effects at an early stage in the onset of cancer, as the supplements were effective soon after the carcinogen insult. Comparison of the apoptotic indices between the two oligosaccharide diets showed no significant difference even though the mean apoptotic index was higher in animals fed long chain inulin. For all animals, apoptosis was significantly higher in the distal colon as compared to the proximal colon (P = 0.0002) however no significant site specific effect of diet occurred. There were no significant dietary effects on bacterial enzyme activities or ammonia concentration despite a trend towards increased colonic beta-glucosidase and reduced ammonia concentration during the oligosaccharide diets. This is the first time that a significant effect of chicory fructans on apoptosis has been shown and the results contribute to the growing evidence that chicory fructans may have cancer preventing properties.

Ammonia↗
PubMed1986

Effect of intraperitoneal insulin on solute kinetics in CAPD: insulin kinetics in CAPD.

The authors evaluated the transport kinetics of insulin and inulin administered intraperitoneally to six diabetic patients undergoing continuous ambulatory peritoneal dialysis. The mass transfer coefficients (MTC) calculated from dialysate to blood for 1.5% and 4.25% dextrose dialysate were (ml/min): insulin 2.9 +/- 0.9, 2.0 +/- 0.5; inulin 3.3 +/- 1.4; 2.9 +/- 1.7, respectively. The MTC for inulin calculated from blood to dialysate was 2.0 +/- 0.7 ml/min. Because insulin disappears from the peritoneal cavity at a rate similar to inulin, it suggests that insulin transport can be defined by diffusion. The derived MTC values for glucose were not altered by the addition of intraperitoneal insulin. The derived MTCs for eight diabetic to thirteen nondiabetic patients were compared. The MTC derived for urea was less among the diabetics (16.6 +/- 2.2 vs. 24.6 +/- 2.6 p less than 0.05), but there were no differences for creatinine, uric acid, glucose, inulin, and protein. The derived values were found to be normally distributed and patients in the upper quartile for one solute were generally in the upper quartile for other solutes.

Ascitic Fluid↗
PubMed2001

Plasma clearance of iodine contrast media as a measure of glomerular filtration rate in critically ill patients.

OBJECTIVE: The selection of the optimal method for assessing renal function relies on the accuracy of the technique. Plasma clearance of nonradioactive iodine contrast media (i.e., iohexol or iopromide) has been suggested as a reliable alternative to the renal clearance of inulin for estimating glomerular filtration rate (GFR). The accuracy of this method when used with critically ill patients displaying different levels of renal function in an intensive care unit (ICU) has not, until now, been examined. DESIGN: The accuracy of double- and multiple-point iohexol or iopromide plasma clearances was compared with that of already established techniques for measuring GFR (creatinine clearance, formula clearance by Cockcroft and Gault) and with that of inulin clearance, which is regarded as the gold standard for the measurement of GFR. PATIENTS: Values were obtained from 31 ICU patients who exhibited a wide range of renal function (serum creatinine: 0.6-6.7 mg/dL). MEASUREMENTS: Inulin clearance was performed using the constant-infusion technique. Creatinine clearance was determined from 24-hr urine samples. The clearance formula was calculated according to Cockcroft and Gault's formula. Iohexol or iopromide were applied as a single intravenous dose, and blood samples were taken up to 6 hrs after the injection. Iodine concentrations were determined by radiographic fluorescence. RESULTS: Plasma clearance of iohexol/iopromide measured after the single injection of contrast media and that of the conventional inulin clearance was almost identical (y = 0.971x + 7.65, r2 =.96; n = 31). Two-point clearance of iohexol/iopromide (double sampling technique) was as reliable as the three-point clearance (three-slope-intercept method, y = 0.995x + 0.62, r2 =.999; n = 18). With respect to inulin clearance, GFR measurements determined by creatinine clearance or according to the formula given by Cockcroft and Gault revealed errors that increased proportionally (y = 1.03x, r2 =.88; n = 27; and y = 0.93x, r2 =.62; n = 31, respectively). It could also be shown that the accuracy of GFR measurements involving plasma clearance of iohexol was not greatly affected by the degree of renal insufficiency or the route by which contrast media were applied. CONCLUSION: These findings indicate that the determination of plasma clearance of iohexol/iopromide is a simple, rapid, and accurate method that can indeed be used for estimating GFR in ICU patients with normal renal function or even different degrees of renal insufficiency.

Adult↗
PubMed2004

Assessing renal graft function in clinical trials: can tests predicting glomerular filtration rate substitute for a reference method?

BACKGROUND: In clinical trials, comparison of renal graft function needs a rigorous determination of glomerular filtration rate (GFR). Since reference methods to measure GFR cannot be easily implemented, a number of tests predicting GFR are usually used. However, little is known about their validity in renal transplant patients. We aimed to compare the performances of six GFR tests with inulin clearance in this population. METHODS: Five hundred consecutive inulin clearances performed in 294 renal transplant recipients with stable renal function were retrospectively selected. For each of them, we computed six estimates: the 24-hour creatinine clearance, the Cockcroft-Gault, Walser, Jelliffe, Nankivell, and Levey formulas. Their respective performance was assessed by correlation (simple linear regression), accuracy (dispersion of true error), and agreement (Bland and Altman method). RESULTS: Each GFR test closely correlated with inulin clearance (P < 0.0001). Comparisons between pairs of GFR tests did not show any significant difference in accuracy between the Levey, Jelliffe, and Walser formulas. Conversely, each of these formulas demonstrated a significant lower dispersion (P < 0.005) than the others. Nevertheless, all GFR tests displayed considerable lack of agreement with limits of agreement over 40 mL/min/1.73 m2 apart. The proportion of predicted GFR differing from inulin clearance by +/- 10 mL/min/1.73 m2, ranged from 34% for the Jelliffe formula to 53% for the Nankivell's one. CONCLUSION: None of these formulas seems to be able to safely substitute for inulin clearance. In clinical trials, renal graft function should be preferably assessed using a reference method of GFR measurement.

Adult↗
PubMed1975

Bulk flow in the cerebrospinal fluid system of the dog.

Ventriculo-cisternal, intracranial subarachnoid-to-subarachnoid space and spinal subarachnoid space perfusions were carried out on dogs. The perfusate contained inulin as a tracer and the design of these experiments was based upon the concept that inulin leaves cerebrospinal fluid (CSF) compartments only by means of bulk absorption, and that actual diffusion and active transport of inulin is negligibly small. Inulin was removed from different CSF spaces by bulk absorption at rates which varied linearly with hydrostatic pressure. The rate of formation of CSF is equal to inulin clearance plus the difference between outflow and inflow rates. The total CSF formation in dogs weighing 12 to 17 kg was measured as 0.065 ml/min, and 58.5 per cent of this amount was found to come from extraventricular CSF space. The rates are independent of hydrostatic pressure in the range studied.

Animals↗
PubMed1975

Changes in renal haemodynamics and electrolyte excretion during acute hyperkalemia in conscious adrenalectomized sheep.

The p-aminohippurate (PAH) clearance, inulin clearance and the excretion of electrolytes by 10 adrenalectomized sheep were measured before, during and after the infusion of 0-43 M-KCl at 2 ml./min for 2 hr. The PAH clearance increased as the plasma potassium concentration increased up to approximately 6-0 m-mole/l. Further increases in plasma potassium were associated with a progressive return of the PAH clearance to or below the pre-infusion levels. At its maximum the PAH clearance was 1-228 +/- 0-032 (S.E. of mean) times the pre-infusion levels. The inulin clearance increased to reach a mazimum coincident with or subsequent to the maximum PAH clearance. The maximum level of inulin clearance during the hyperkalaemia was 1-158 +/- 0-020 times the pre-infusion clearance. The increments in the clearance of potassium and of bicarbonate rose rapidly to exceed the increment in inulin clearance during the hyperkalaemia in all experiments. The increments in the clearance of sodium and of chloride exceeded the increment in inulin clearance in more than half the experiments. It was concluded that although hyperkalaemia was associated with increased glomerular filtration much of the increased excretion of sodium, chloride and bicarbonate was derived from depressed tubular reabsorption of the ions. When the infusion experiments were repeated on the same animals the sheep demonstrated an improved ability to control the rise in plasma potassium concentration which was similar to potassium adaptation described in other species. There were no apparent differences between sheep maintained on 1-5 mg and 5 mg deoxycorticosterone acetate daily in their adaptation to potassium loading and the effect was tentatively attributed to the level of steroid maintenance being chronically high. The toxicity of hyperkalaemia was not lessened by this adaptation to potassium loading.

Adrenalectomy↗
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↗
PubMed1980

Evidence for renal tubular leakage in maleic acid-induced Fanconi syndrome.

Micropuncture and microinjection studies were performed in Sprague-Dawley rats 20 h after subcutaneous injection of buffered maleic acid (MA) or buffer alone in experimental and control rats, respectively. Collections were made from earliest and latest accessible portions of proximal tubule (PT). Lissamine green injections and microperfusion of PT demonstrated leakage of lissamine green from late PT sites in MA-treated rats, whereas inulin leakage occurred at a more distal site. Whole kidney GFR was 58% lower in MA-treated rats despite comparable single nephron GFR in PT of both groups. Microinjections of PT with [methoxy-3H]inulin resulted in injected inulin recovery from the contralateral kidney in MA-treated rats of 24.0 +/- 2.0 compared with 4.7 +/- 0.89% in controls, suggesting that tubular leakage of inulin accounted for the lower whole kidney GFR. Net sodium and phosphate transport in early PT was similar in both groups but was decreased in late PT segments in MA-treated rats. Sodium and phosphate excretion in final urine were, however, comparable in both groups. The significantly lower plasma phosphate concentration might account for the blunted phosphaturia in MA-treated rats. These studies demonstrate a segmental effect of MA on 1) tubular leakage to lissamine green from late PT and inulin beyond the late PT, and 2) decreased net sodium and phosphate transport in the PT.

Animals↗
PubMed1982

Transcapillary exchange of molecular weight markers in the postglomerular circulation: application of a barrier-limited model.

The permselectivity of the postglomerular capillary wall was studied by performing pulse-injection multiple indicator-dilution experiments on dog kidneys in vivo, using simultaneous injection of T1824-labeled albumin (plasma reference), creatinine (extracellular reference), and one or two radioactively labeled indicators: raffinose (595 dalton), vitamin B12 (1,357 dalton), or inulin (approximately 5,000 dalton). The urine transit patterns superimposed for all these except albumin, suggesting equal permeability for these molecular weight markers at the level of the glomerular filtration barrier. But the renal vein mean transit times progressively decreased. Therefore, their apparent interstitial volumes of distribution decrease with increasing molecular weight. This could be due to several factors acting singly or in combination: reduced capillary permeability in the postglomerular microcirculation; restricted diffusion in the postglomerular interstitium; or excluded volume effects. Evidence suggested that the effect was due to a combination of permeability and exclusion volume effects. To assess the validity of this assumption, the barrier-limited model was compared with the experimental data. The results were analyzed (both hydropenic and mannitol-diuretic dogs) and best fits calculated using two independent parameters, permeability and excluded volume. For permeability (X10(-4) cm/s, mean +/- SD) the range of values was always greater than or equal to 15 for creatinine and raffinose, and greater than or equal to 12 for B12. The permeability for inulin was 6.9 +/- 1.4. When interstitial volume excluded was expressed as percentage of the volume available to creatine, the excluded volume was negligible for raffinose and B12 but 12 +/- 5% for inulin. During mannitol diuresis the permeability for creatinine and raffinose remained high, but the values tended to decrease for B12. The permeability of inulin decreased to 2.9 +/- 0.09. Mannitol diuresis increased the excluded volume of inulin but did not alter the creatinine, raffinose, or B12 value.

Animals↗
PubMed1983

Determination of postglomerular permselectivity to neutral dextrans in the dog.

The single-pass multiple-indicator-dilution (MID) technique was used to analyze postglomerular capillary permeability. Anesthetized mongrel dogs (n = 13) during mannitol diuresis received a pulse injection of 125I-albumin (plasma reference), [14C]inulin (glomerular reference), creatinine (interstitial reference), and a homogeneous [3H]dextran molecular weight marker 6,000-12,000 dalton in the left renal artery. Simultaneous left renal venous outflow and right and left urine were rapidly sampled. Left urine recoveries of creatinine, [14C]inulin, and [3H]dextran were identical, indicating no glomerular solute flux limitation. Progressive precession of the [14C]inulin and [3H]dextran renal vein curves relative to creatinine indicated increasing postglomerular limitation to solute flux proportional to molecular size. The postglomerular solute extraction (EPG) (renal vein upslope indicator/125I-albumin) varied inversely with postglomerular renal plasma flow (F), indicating diffusion limitation. Ouabain infusion into the left renal artery significantly reduced Na reabsorption but did not alter the EPG of [14C]inulin or [3H]dextran. Permeability-surface (PS) area products calculated from EPG and F ranged from 4.86 +/- 0.89 to 0.97 +/- 0.25 (SD) cm X s-1 X 100 g-1 for indicators 5,000-12,000 dalton. [14C]Inulin PS products remained constant for F greater than or equal to 2.50 ml X s-1 X 100 g kidney-1. PS[3H]dextran/PS[14C]In (n = 20, F greater than or equal to 2.5 ml X s-1) was used to calculate an effective postglomerular capillary pore radius, r = 55.5 +/- 7.6 (SD) A.

Animals↗
PubMed1999

Measurement of glomerular filtration rate by the 99mTc-DTPA renogram is less precise than measured and predicted creatinine clearance.

The work was devised to compare measurements of glomerular filtration rate (GFR) by technetium-99m-diethylenetriaminepentacetic acid (99mTc-DTPA) renogram to those by creatinine clearance (measured and predicted by Cockroft and Gault) and by inulin clearance. A total number of 65 individuals were enrolled: 15 healthy controls and 50 patients with renal disease. Compared to inulin clearance used as the gold standard, 99mTc-DTPA overestimated at low and underestimated at high GFRs. 99mTc-DTPA measurements were less precise than creatinine clearance except for individuals with GFR >100 ml/min x 1.73 m2. Measured creatinine clearance had the highest correlation coefficient with inulin clearance, 99mTc-DTPA clearance the lowest. In correlation analyses, 81.5% of the interindividual variability for measured creatinine clearance could be explained by true differences in inulin clearance; this value dropped to 59.1 and 57.4% for predicted creatinine clearance and 99mTc-DTPA, respectively. In patients with GFR <25 ml/min x 1.73 m2, all 99mTc-DTPA measurements were out of the 95% confidence interval for the inulin measurement. It can be inferred that 99mTc-DTPA clearance from the renogram is less precise than measured and predicted creatinine clearance.

Adult↗
PubMed2006

Cystatin C--a marker for assessment of the glomerular filtration rate in patients with cisplatin chemotherapy.

BACKGROUND: Cystatin C has recently been proposed as an ideal marker for glomerular filtration rate (GFR). In this study, cystatin C serum levels were evaluated in comparison to serum creatinine concentrations and inulin clearances in patients with normal kidney function receiving cisplatin-based chemotherapy to assess the validity of cystatin C as an alternative endogenous marker of GFR. METHODS: Blood samples for the assessment of cystatin C, creatinine and inulin clearances were collected in patients before and after application of cisplatin in a clinical trial. Overall, 41 patients were included in the study, 35 of them were eligible receiving cisplatin in two different cisplatin-based chemotherapy schedules. RESULTS: A 21% increase of cystatin C serum levels was demonstrated in the placebo group after application of cisplatin. Analysis of inulin clearances revealed a 23% loss of inulin clearance in patients of the placebo arm. In contrast, significant changes could not be detected by analysis of serum creatinine levels. CONCLUSIONS: Cystatin C represents a more sensitive clinical marker than serum creatinine for the early assessment of GFR damage caused by cisplatin. Changes in cystatin C serum concentrations correlate well to GFR decrease as measured by inulin clearance.

Adult↗
PubMed1995

Plasma clearance of nonradioactive iohexol as a measure of glomerular filtration rate.

Renal clearance of inulin is the best available indicator of GFR but cannot be used routinely for clinical purposes and is also difficult to perform for clinical investigation when repeated measurements are required. The aim of this study was to find a reliable alternative to inulin clearance that would allow one to avoid the use of radioactivity and problems related to the continuous infusion of the marker. The plasma clearance of unlabeled iohexol, a nonionic contrast agent, was used. Forty-one patients (creatinine clearance 6 to 160 mL/min per 1.73 m2) underwent simultaneous measurements of renal clearance of inulin and plasma clearance of iohexol. Iohexol was given as a single iv dose, and blood samples were drawn up to 600 min after the administration. Iohexol concentrations (by HPLC) were analyzed by a two-compartment, open-model system. A highly significant correlation between the plasma clearance of iohexol and the renal clearance of inulin over a wide range of GFR values was found. By analyzing the data with a simplified method that uses a one-compartment model corrected with the Bröchner-Mortensen formula, an excellent correlation with the inulin clearance was also observed. When only patients with moderate to severe renal failure were considered, a significant correlation between the two methods was found. A further comparison between GFR determined with iohexol and iopromide, a new low-osmolarity, low-viscosity contrast medium, was also performed in a subgroup of patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed2002

Delayed transcapillary transport of insulin to muscle interstitial fluid in obese subjects.

Insulin-resistant subjects have a slow onset of insulin action, and the underlying mechanism has not been determined. To evaluate whether a delayed transcapillary transport is part of the peripheral insulin resistance, we followed the kinetics of infused insulin and inulin in plasma and muscle interstitial fluid in obese insulin-resistant patients and control subjects. A total of 10 lean and 10 obese men (BMI 24 +/- 0.8 vs. 32 +/- 0.8 kg/m(2), P < 0.001) was evaluated during a hyperinsulinemic-euglycemic clamp (insulin infusion rate 120 mU. m(-2). min(-1)) combined with an inulin infusion. Measurements of insulin and inulin in plasma were taken by means of arterial-venous catheterization of the forearm and microdialysis in brachioradialis muscle combined with forearm blood flow measurements with vein occlusion pletysmography. The obese subjects had a significantly lower steady-state glucose infusion rate and, moreover, demonstrated a delayed appearance of insulin (time to achieve half-maximal concentration [T(1/2)] 72 +/- 6 vs. 46 +/- 6 min in control subjects, P < 0.05) as well as inulin (T(1/2) 83 +/- 3 vs. 53 +/- 7 min, P < 0.01) in the interstitial fluid. Also, the obese subjects had a delayed onset of insulin action (T(1/2) 70 +/- 9 vs. 45 +/- 5 min in control subjects, P < 0.05), and their forearm blood flow rate was significantly lower. These results demonstrate a delayed transcapillary transport of insulin and inulin from plasma to the muscle interstitial fluid and a delayed onset of insulin action in insulin-resistant obese subjects.

Adult↗
PubMed1999

Measurement of changes in glomerular filtration rate induced by atrial natriuretic peptide in the rat kidney.

This study was undertaken to improve the measurement of glomerular filtration rate (GFR) during the acute diuretic phase induced by atrial natriuretic peptide (ANP), which may indeed alter the renal clearance of inulin (GFRCL) due to dead space error. A technique to measure GFR without urine collections was therefore developed in anaesthetized rats prepared as for micropuncture. To do so, arterial blood was periodically collected and renal venous blood was withdrawn simultaneously from a catheter inserted into the left suprarenal vein to determine the renal extraction coefficient of inulin (CEIN). In addition, renal blood flow (RBF) was continuously measured with an electromagnetic flow transducer fitted around the left renal artery to estimate renal plasma flow (RPF). GFR (GFRCE) was then calculated as the product of RPF and CEIN. To study the effects of ANP on GFR, rats were injected i.v. with 10 microliters of saline without (n = 6; vehicle) or with 1 microgram ANP (n = 6; ANP) and GFRCE and GFRCL were compared before and after each treatment. They did not differ significantly during baseline measurements in each experimental group and were not modified after vehicle. Similarly, RBF remained constant. In contrast, RBF and GFRCE increased rapidly and simultaneously 90 s after ANP, from 9.07 +/- 0.25 to 10.07 +/- 0.35 (12%) and from 1.209 +/- 0.188 to 1.715 +/- 0.190 ml min-1 (42%), respectively (P < 0.05). GFRCL increased to an even greater extent (88%). Moreover, the peak enhancement of GFRCL was delayed and occurred 180 s after ANP. The renal clearance of inulin was thus unduly elevated due to sudden changes in the dead space induced by the diuretic effect of ANP. In conclusion, determination of glomerular filtration rate by the method of renal extraction of inulin provided more reliable results than those achieved using the classical method of renal clearance of inulin. Moreover, it was sufficiently sensitive to detect small and transient changes in GFR induced by the injection of 1 microgram ANP.

Animals↗
PubMed1999

Mutational analysis of avidity and fine specificity of anti-levan antibodies.

Using the polyfructose, bacterial levan, as a model polysaccharide, we analyzed how V regions affect binding in anti-polysaccharide mAbs. Previously, panels of mAb were constructed from bacterial levan-immunized BALB/c and CBA/Ca mice. The BALB/c mAb were mostly germline VHJ606:Vkappa11, and a subset contained presumed somatic mutations in the complementarity-determining regions (CDRs) that correlated with increases in avidity for the beta(2-->1) inulin linkage of levan. The CBA/Ca mAb were more heterogeneous in V gene usage, but a subset of inulin-nonreactive mAb were VHJ606:Vlambda and had VH sequence differences in the CDRs from the VHJ606 regions of the BALB/c mAb. In this report, VHJ606 Abs containing various combinations of specifically mutated H and L chains were produced by engineered transfectants and tested for inulin avidity and levan binding. Two presumed somatic mutations seen in CDRs of the BALB/c hybridomas were shown to directly cause marked increases in avidity for inulin (VH N53H, 9-fold; VL N53I, 20-fold; together, 46-fold) but not for beta(2-->6) levan. Exchange of either positions 50 or 53 in VH or the H3 loop between the BALB/c and CBA/Ca mAb resulted in either fine specificity shift or total loss of bacterial levan binding. Three-dimensional models of the V regions suggested that residues that affect binding to inulin alone are near the edge of the CDR surface, while residues involved with binding both forms of levan and affecting fine specificity are in the VH:VL junctional area.

Amino Acid Sequence↗
PubMed1992

Residual volume measurements in CAPD patients with exogenous and endogenous solutes.

Accurate residual volume (RV) measurements are needed in studies on fluid kinetics during CAPD. In this study 10 stable CAPD patients were examined twice within 1 week. On both occasions RV after drainage was calculated by the indicator dilution method. Exogenous (dextran 70, inulin) and endogenous (albumin, IgG, urea, creatinine) solutes were used as markers. RV calculated with endogenous solutes (mean +/- SD) were significantly higher than those calculated with dextran (232 +/- 77 mL) and inulin (223 +/- 73): albumin (389 +/- 123), IgG (497 +/- 180), urea (465 +/- 129) and creatinine (429 +/- 109). The relationship between RV calculated with exogenous solutes was much better than between those calculated with endogenous solutes: dextran vs inulin (r = 0.91), albumin vs IgG (r = 0.69) and urea vs creatinine (r = 0.63). Since mass transport of endogenous solutes during rinsing time exceeds mass transport of dextran and inulin, RV was also calculated after corrections had been made for diffusive mass transport of endogenous solutes during the rinsing procedure. After this correction only albumin was similar to exogenous solutes (244 +/- 111 mL) and had an acceptable confidence interval when compared to dextran. No correlation was found between RV on the first and second day, suggesting large intra-individual variability. We conclude that RV should be calculated with dextran or inulin. When no exogenous solutes are used, albumin is the best alternative. However, only rough estimations are obtained when no correction for diffusion is applied.

Adult↗
PubMed1987

Assessment of glomerular filtration rate in infants. Comparison of three methods used in clinical practice.

Glomerular filtration rate was assessed in 66 infants less than 1 year of age. Results obtained by 3 different routine methods were compared to those obtained by the standard inulin clearance (GFR): 1. clearance values calculated from plasma creatinine concentration (mg/dl) and height (cm), using a k value of 0.55 derived from inulin clearance did not reliably reflect GFR (Y = 37.5 + 0.51 Cin, r = 0.82); 2. creatinine clearance values calculated over 3 h overestimated standard inulin clearance at all levels of GFR below 100 ml/min.1.73m2 (Y = 25.1 + 0.75 Cin, r = 0.77). 3. Clearance values calculated as the sum of twice the creatinine clearance plus the urea clearance, divided by 3, overestimated the standard inulin clearance at low levels of GFR and underestimated it at high GFR (Y = 20.6 + 0.66 Cin, r = 0.82). The study of several techniques for estimating GFR in infants demonstrates that there is no ideal substitute for the traditional inulin clearance when precise measurement of glomerular filtration rate is needed, and that simple 3 h creatinine clearances represent a satisfactory and rational estimate of GFR in clinical practice.

Age Factors↗