Plasma Exogenous Creatinine Clearance Research Articles

Comparative physiology of glomerular filtration rate by plasma clearance of exogenous creatinine and exo-iohexol in six different avian species

Early diagnosis of kidney diseases in avian species is limited. Endogenous markers currently used in avian practice are not sensitive enough to identify early kidney failure. Consequently, alternative markers should be evaluated. To be able to evaluate these alternative markers, an accurate marker to estimate the GFR should be validated. This study determined the GFR, measured as clearance of exogenous creatinine and exo-iohexol, in six different bird species, i.e. broiler chickens, laying chickens, turkeys, Muscovy ducks, pigeons and African grey parrots (4♀/4♂). To be able to compare the six bird species, normalization to bodyweight (BW) of the GFR was performed, after a good correlation between BW and kidney weight was demonstrated (R² = 0.9836). Clearance of exo-iohexol normalized to BW (mL/min/kg) was determined in all bird species, i.e. 3.09 in broiler chickens; 2.57 in laying chickens; 1.94 in turkeys; 1.29 in pigeons; 2.60 in ducks and 1.11 in parrots. However, these results differed significantly with the clearance of exogenous creatinine: 8.41 in broiler chickens; 9.33 in laying chickens; 5.62 in turkeys; 14.97 in pigeons; 17.59 in ducks and 25.56 in parrots 25.56. Iohexol is preferred to measure the GFR, since it is not prone to tubular reabsorption nor secretion.

Assessment of symmetric dimethylarginine as a biomarker of renal function in hyperthyroid cats treated with radioiodine.

BackgroundMeasurement of serum creatinine (sCr) and urea nitrogen fail to detect decreased renal function in many hyperthyroid cats because of low muscle mass and glomerular hyperfiltration of affected cats. Serum symmetric dimethylarginine (sSDMA) is an earlier and more sensitive renal biomarker than sCr.ObjectiveEvaluate sSDMA as a biomarker of renal function in hyperthyroid cats before (T0) and 1 month after (T1) radioiodine (131I) treatment.AnimalsForty‐seven client‐owned hyperthyroid nonazotemic cats were evaluated at T0 and T1.MethodsA prospective study in which sCr and sSDMA concentrations were determined in 47 hyperthyroid cats at T0 and at T1. Glomerular filtration rate (GFR) was estimated at T0 and T1 in 10 of these 47 cats using plasma exogenous creatinine clearance test.ResultsSerum SDMA was elevated (>14 μg/dL) in 6 of 47 cats at T0 and normalized after treatment in 4 of those cats. All cats remained nonazotemic after treatment. In 10 cats in which GFR was measured, correlation between GFR and sSDMA was low and not significant (τb = −0.35, P = .17 at T0 and τb = −.22, P = .41 at T1), whereas correlation between GFR and sCr was moderate and significant (τb = −0.52, P < .05 at T0 and τb = −.53, P = <.05 at T1).Conclusions and Clinical ImportanceCareful interpretation of mildly increased sSDMA with normal sCr in hyperthyroid cats is warranted as sSDMA values might normalize after resolution of hyperthyroidism in some cats. In this population of hyperthyroid cats, sSDMA was poorly correlated with GFR.

Plasma exogenous creatinine clearance in clinically healthy cats: Comparison with urinary exogenous creatinine clearance, tentative reference intervals and indexation to bodyweight

Glomerular filtration rate (GFR) is considered to be the best indicator of overall kidney function. The major objectives of this study were to compare plasma exogenous creatinine clearance (PECC) with a reference method, to establish reference intervals (RIs) for PECC and to assess the effects of indexation of GFR to bodyweight (BW) in cats. PECC was compared with urinary clearance of exogenous creatinine (UECC) in six clinically healthy domestic shorthair cats (experiment 1). Tentative RIs were determined according to current guidelines and the effects of indexation to BW and of covariables on GFR were assessed in 43 clinically healthy cats of various breeds (experiment 2).PECC was 15% higher than UECC (P < 0.01), but the two estimates were strongly correlated (r2 = 0.97, P = 0.001). RIs for PECC were 6.4–21.3 mL/min or 1.2–4.9 mL/min/kg. The absolute (i.e. non-indexed) GFR value was not dependent on BW. Thus, indexation of GFR to BW in cats would not standardize the GFR value, but could introduce bias in clinical interpretation. Significant effects of breed, plasma protein concentration and plasma albumin concentration on GFR were demonstrated. Plasma concentrations of urea and creatinine, when assessed separately, were also weakly correlated with GFR in healthy cats. These combined findings contribute to a better understanding of renal function assessment in cats.

Scintigraphy and exogenous creatinine clearance to assess renal function in a Newfoundland dog with ureteral ectopia

A nine-month-old intact female Newfoundland dog was presented for evaluation of an ectopic ureter without lower urinary tract signs. Due to progression of the disease and periodic urinary infections, a...

Assessment of glomerular filtration rate in normally hydrated and&lt;br&gt;dehydrated dromedary camel by plasma exogenous creatinine clearance test

The main objective of this study was to assess glomerular filtration rate (GFR) in the camels (Camelus dromedarius) under free water access and dehydration conditions (after a 34 days-period of water deprivation) using plasma exogenous creatinine clearance without urine collection. Trials were carried out on six nonpregnant, non-lactating and healthy female camels. Creatinine was administered as an IV bolus at a dose of 16 mg/kg body weight. Blood samples were collected at predetermined times over 24 h post-injection. Plasma creatinine concentration was analysed using Jaffe method. Creatinine clearance was calculated by pharmacokinetic analysis using a non-compartmental approach. Water deprivation induced a significant 15%decrease in body weight but did not affect haematocrit and total plasma proteins. Mean corpuscular volume increased and red blood cells number decreased in dehydrated conditions. Dehydration produced a significant 30%-increase in plasma creatinine and mean residence time and a significant 20%-decrease in GFR. In conclusion, water deprivation decreased glomerular filtration and plasma exogenous creatinine clearance test could be used as a practical method for GFR assessment in dromedary camel in field conditions.

Plasma Clearance of Exogenous Creatinine, Exo‐Iohexol, and Endo‐Iohexol in Hyperthyroid Cats before and after Treatment with Radioiodine

Glomerular filtration rate (GFR) can be measured by clearance methods of different markers showing discrepancies and different reproducibility in healthy cats. Studies comparing different methods of GFR measurement in hyperthyroid cats have not yet been performed. Plasma clearance of exogenous creatinine (PECCT), exo-iohexol (PexICT), and endo-iohexol (PenICT) could lead to differences in GFR measurement and the need to use the same clearance method when comparing GFR before and after radioiodine treatment in hyperthyroid cats. Fifteen client-owned hyperthyroid cats. GFR was measured 1 day before and 1, 4, 12, and 24 weeks after treatment. Intravenous injection of iohexol was followed immediately by IV injection of creatinine. Plasma creatinine was measured by an enzymatic method. Plasma endo- and exo-iohexol were measured by high-performance liquid chromatography coupled to ultraviolet detection. Globally, the 3 GFR methods resulted in significantly different (P < .001) GFR results. GFR results among the different methods were the same (P= .999) at all time points. All 3 techniques indicated decreasing GFR after (131)I treatment. For each GFR technique, a significant decrease in GFR was observed between time point 0 and all other time points. This decrease stabilized 4 weeks after treatment, with very little decline afterward. It is mandatory to use the same GFR technique in follow-up studies. GFR testing at 4 weeks posttreatment could allow assessment of the final renal functional loss after treatment in hyperthyroid cats.

Comparison of a New Blood Sampling Device With the Vacuum Tube System for Plasma and Hematological Analyses in Healthy Dogs

Pediatric devices based on a capillary system may provide an alternative to vacuum tubes for canine blood sampling. The potential advantages are absence of vein collapse, limited blood volume sampled, and improved safety. The aim of this study was to compare routine plasma and hematological variables in seven healthy dogs using both techniques. Five biochemical analytes were measured, and a complete hematological examination and plasma exogenous creatinine clearance test were performed. No clinically relevant difference between the two techniques was observed for any variable or functional test assessed.

Comparison and Reproducibility of Plasma Clearance of Exogenous Creatinine, Exo‐iohexol, Endo‐iohexol, and51Cr‐EDTA in Young Adult and Aged Healthy Cats

Background: Important characteristics determining the usefulness of a method for glomerular filtration rate (GFR) measurement are convenience, availability, and reproducibility.Hypothesis: The use of different plasma clearance methods could lead to different results and differences in reproducibility.Animals: Twelve healthy cats: 6 young adult cats (age 7–12 months), and 6 aged cats (age 9–12 years) were included in this study.Methods: A cross‐over design was used to compare the plasma clearance of exogenous creatinine (PECCT), exo‐iohexol (PexICT), endo‐iohexol (PenICT), and chromium‐51 ethylenediaminetetraacetic acid (51Cr‐EDTA), and to investigate reproducibility of these methods. Cats of different ages were included to determine if differences in GFR in young adult versus aged cats would be detected with these methods. The PECCT, PexICT, and PenICT were performed in a combined manner. Plasma data were subjected to noncompartmental (creatinine, exo‐iohexol, and endo‐iohexol) or bicompartmental (51Cr‐EDTA) analysis with a statistical moment approach. Area under the concentration‐time curve was calculated using the trapezoidal rule with extrapolation to infinity. Statistical analyses were carried out using a random effects model.Results: Globally, the 4 methods differed significantly (P&lt;.0001) in GFR assessment. Clearance of exo‐iohexol and chromium‐51 ethylenediaminetetraacetic acid (51Cr ‐EDTA) showed the highest and lowest reproducibility, respectively. Only plasma clearance of creatinine differed significantly between young adult and aged cats.Conclusion and Clinical Importance: We found considerable differences in reproducibility of different GFR measurements. These findings should be taken into account not only in practice but also in future studies involving GFR measurement.

Comparison and Reproducibility of Plasma Clearance of Exogenous Creatinine, Exo-iohexol, Endo-iohexol, and 51Cr-EDTA in Young Adult and Aged Healthy Cats

Important characteristics determining the usefulness of a method for glomerular filtration rate (GFR) measurement are convenience, availability, and reproducibility. The use of different plasma clearance methods could lead to different results and differences in reproducibility. Twelve healthy cats: 6 young adult cats (age 7-12 months), and 6 aged cats (age 9-12 years) were included in this study. A cross-over design was used to compare the plasma clearance of exogenous creatinine (PECCT), exo-iohexol (PexICT), endo-iohexol (PenICT), and chromium-51 ethylenediaminetetraacetic acid (51Cr-EDTA), and to investigate reproducibility of these methods. Cats of different ages were included to determine if differences in GFR in young adult versus aged cats would be detected with these methods. The PECCT, PexICT, and PenICT were performed in a combined manner. Plasma data were subjected to noncompartmental (creatinine, exo-iohexol, and endo-iohexol) or bicompartmental (51Cr-EDTA) analysis with a statistical moment approach. Area under the concentration-time curve was calculated using the trapezoidal rule with extrapolation to infinity. Statistical analyses were carried out using a random effects model. Globally, the 4 methods differed significantly (P < .0001) in GFR assessment. Clearance of exo-iohexol and chromium-51 ethylenediaminetetraacetic acid (51Cr -EDTA) showed the highest and lowest reproducibility, respectively. Only plasma clearance of creatinine differed significantly between young adult and aged cats. We found considerable differences in reproducibility of different GFR measurements. These findings should be taken into account not only in practice but also in future studies involving GFR measurement.

Plasma Exogenous Creatinine Clearance Test in Dogs: Comparison with Other Methods and Proposed Limited Sampling Strategy

Plasma clearance of creatinine was evaluated for assessment of glomerular nitration rate (GFR) in dogs. In 6 healthy dogs (Experiment 1), we determined 24‐hour urine clearance of endogenous creatinine, plasma, and urine clearances of exogenous creatinine administered at 40, 80, and 160 mg/kg in a crossover design (linearity study), plasma iothalamate clearance, and plasma and urine clearances of14C‐inulin. In Experiment 2, plasma creatinine and iothalamate clearances were compared, and a linearity study was performed as for Experiment 1 in 6 dogs with surgically induced renal impairment. Experiment 3 compared plasma creatinine clearance with plasma iothalamate clearance before and 3 weeks after induction of moderate renal impairment in 6 dogs. Plasma creatinine clearances were calculated by both noncompartmental and compartmental analyses. In Experiment 1, plasma inulin clearance was higher (P&lt; .001) than other clearance values. Plasma creatinine clearances at the 3 dose rates did not differ from urine inulin clearance and each other. In Experiment 2, plasma creatinine clearances were about 14% lower than plasma iothalamate clearance (P&lt; .05). In Experiment 3, decreases in GFR assessed by plasma clearances of iothalamate and creatinine were similar. Renal failure decreased the daily endogenous input rate of creatinine by 25%. Limiting sampling strategies for optimizing GFR calculation were proposed, allowing an error lower than 6.5% with 4 blood samples. These results suggest that determination of plasma creatinine clearance by a noncompartmental approach offers a reliable, inexpensive, rapid, and convenient means of estimating GFR in routine practice.

Use of fluorescence HPLC for determining extrarenal creatinine clearance in rats

In order to clarify whether plasma creatinine concentration is overestimated due to the presence of non-creatinine chromogens when determined by the Jaff/'e method and also to elucidate the significance of tubular secretion in relation to creatinine clearance, the creatinine clearance in rats was measured by the use of a fluorescence HPLC method for the specific determination of creatinine. When creatinine was determined by the Jaffé method, plasma creatinine concentration was always overestimated. When creatinine was determined by the fluorescence HPLC method, the clearance of endogenous creatinine was found to be hardly influenced by tubular secretion, and it appears to be a reliable index of GFR in rats with normal renal function. The clearances for endogenous and exogenous creatinine were well correlated to inulin clearance, although the clearance of exogenous creatinine at plasma concentrations ranging from 22.6 to 289.9 μg/ml was slightly higher than the inulin clearance. The phenomenon of extrarenal clearance of exogenous creatinine was studied carefully in rats with normal renal function under steady-state conditions and after a single injection. The contribution of extrarenal clearance to overall clearance was 37.9% in the former case and 21.1% in the latter case. Although there is about a 2-fold difference between these values, extrarenal clearance appears to be significant in rats with normal renal function, and plasma clearance of exogenous creatinine cannot be necessarily regarded as a valid index of GFR.