Comparison of three types of analyzers for urine protein-to-creatinine ratios in dogs

BackgroundQuantitation of urine protein is important in dogs with chronic kidney disease. Various analyzers are used to measure urine protein-to-creatinine ratios (UPCR).ObjectivesThis study aimed to compare the UPCR obtained by three types of analyzers (automated wet chemistry analyzer, in-house dry chemistry analyzer, and dipstick reading device) and investigate whether the differences could affect clinical decision process.MethodsUrine samples were collected from 115 dogs. UPCR values were obtained using three analyzers. Bland-Altman and Passing Bablok tests were used to analyze agreement between the UPCR values. Urine samples were classified as normal or proteinuria based on the UPCR values obtained by each analyzer and concordance in the classification evaluated with Cohen''s kappa coefficient.ResultsPassing and Bablok regression showed that there were proportional as well as constant difference between UPCR values obtained by a dipstick reading device and those obtained by the other analyzers. The concordance in the classification of proteinuria was very high (κ = 0.82) between the automated wet chemistry analyzer and in-house dry chemistry analyzer, while the dipstick reading device showed moderate concordance with the automated wet chemistry analyzer (κ = 0.52) and in-house dry chemistry analyzer (κ = 0.53).ConclusionsAlthough the urine dipstick test is simple and a widely used point-of-care test, our results indicate that UPCR values obtained by the dipstick test are not appropriate for clinical use. Inter-instrumental variability may affect clinical decision process based on UPCR values and should be emphasized in veterinary practice.     

Influence of urine pH on accurate urinary protein determination in Sprague-Dawley rats

BACKGROUND: Rat urinary protein concentration is commonly measured during safety assessment studies to evaluate potential drug-induced nephrotoxicity. It has been reported that impregnated reagent test strips (dipsticks) can yield false-positive urinary protein results for alkaline urine samples. OBJECTIVE: The objective of this study was to determine if urinary dipsticks accurately assess protein concentrations, especially in alkaline rat urine. METHODS: Ten male Sprague-Dawley rats were treated with 2% sodium bicarbonate and 2% ammonium chloride to alkalinize and acidify the urine, respectively. Urine pH was measured in treated and control rats using a pH meter and urinary dipsticks with the Clinitek 500. Quantitative urinary protein results were compared to urinary dipstick protein evaluations obtained with the Clinitek 500 and sulfosalicylic acid precipitation test methods. RESULTS: The urinary dipstick pH measurement had a very high correlation (r = .98) with the pH meter technique. Samples with alkaline pH (>or=7.5) analyzed for protein by dipstick analysis were in complete agreement 34.7% of the time with the quantitative technique, which was very similar to the 39.3% agreement for samples with neutral and acidic pH (相似文献   

Plasma and urine pharmacokinetics of intravenously administered flunixin in greyhound dogs

Medication control in greyhound racing requires information from administration studies that measure drug levels in the urine as well as plasma, with time points that extend into the terminal phase of excretion. To characterize the plasma and the urinary pharmacokinetics of flunixin and enable regulatory advice for greyhound racing in respect of both medication and residue control limits, flunixin meglumine was administered intravenously on one occasion to six different greyhounds at the label dose of 1 mg/kg and the levels of flunixin were measured in plasma for up to 96 hr and in urine for up to 120 hr. Using the standard methodology for medication control, the irrelevant plasma concentration was determined as 1 ng/ml and the irrelevant urine concentration was determined as 30 ng/ml. This information can be used by regulators to determine a screening limit, detection time and a residue limit. The greyhounds with the highest average urine pH had far greater flunixin exposure compared with the greyhounds that had the lowest. This is entirely consistent with the extent of ionization predicted by the Henderson–Hasselbalch equation. This variability in the urine pharmacokinetics reduces with time, and at 72 hr postadministration, in the terminal phase, the variability in urine and plasma flunixin concentrations are similar and should not affect medication control.     

Screening for proteinuria in cats using a conventional dipstick test after removal of cauxin from urine with a Lens culinaris agglutinin lectin tip

Proteinuria is an important indicator of urinary tract disease and urine dipsticks are simple and sensitive tools to screen for this marker. However, the use of dipsticks to screen for proteinuria may not be appropriate in cats, since cauxin, a 70 kDa glycoprotein, is secreted by the kidneys in clinically normal animals of this species. To circumvent this problem, a Lens culinaris agglutinin (LCA) lectin tip was developed to remove cauxin from feline urine, followed by conventional urine dipstick testing for proteinuria. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS–PAGE) with Coomassie brilliant blue R-250 staining indicated that >90% cauxin in the urine of 13 clinically normal cats was trapped by the LCA lectin tip, so that the dipstick protein ‘score’ changed from ‘positive’ (?30 mg/dL) for untreated urine to ‘negative’ (?10 mg/dL) for lectin tip-treated urine. In contrast, SDS–PAGE indicated that lectin tip-treated samples from 20 animals with renal disease contained high concentrations of albumin and low-molecular weight proteins; dipstick testing of lectin tip-treated urine resulted in a consistently positive protein score. The accuracy of the dipstick method for detecting cats with abnormal proteinuria is enhanced if dipsticks are used with urine samples that have first been passed through the LCA lectin tip.     

Evaluation the Clinitek status automated dipstick analysis device for semiquantitative testing of canine urine

The aim of this prospective study was to evaluate the Clinitek status™ analyser using Multistix10SG™/Microalbustix™ dipsticks (all: Siemens Dx) for canine urine (n = 101) compared to reference methods: visual reading (Combur9 dipstick, Roche), refractometry, microscopy, and quantitative protein/creatinine analysis (Pentra400, AxonLab). The automated analyses were done twice and visual tests were performed by two examiners.An excellent to good concordance was demonstrated between the first/second analysis with the Multistix10SG and the Combur9 dipstick, respectively with Cohen’s κ-values ranging from 0.776 to 1.000. Agreement between both dipsticks was good for glucose (κ = 0.753), blood (κ = 0.793), protein (κ = 0.788), and moderate for bilirubin (κ = 0.431) and ketones (κ = 0.540). In 6/101 specimens, false positive ketone reactions were obtained with the Multistix10SG™. Multistix10SG™ could not be used for determination of pyuria or specific gravity. Semiquantitative/quantitative protein results correlated well (ρ = 0.90) and creatinine measurements moderately (ρ = 0.76). Due to automated data transmission to the laboratory information system, the Clinitek status™ is of advantage in veterinary laboratories/clinics.     

Comparison of Multistix PRO dipsticks with other biochemical assays for determining urine protein (UP), urine creatinine (UC) and UP:UC ratio in dogs and cats

BACKGROUND: Urine protein: urine creatinine (UP:UC) ratio determined from the quantitative measurement of protein and creatinine in a single urine sample is the best feasible assessment of clinically significant proteinuria in dogs and cats. A dipstick that measures urine protein, urine creatinine, and UP:UC ratio has been used in human medicine and could have application for veterinary practice. OBJECTIVE: The objective of this study was to compare the Multistix PRO dipstick (Bayer Corporation, Elkhart, IN, USA) to other biochemical methods for determination of urine protein and creatinine, and UP:UC ratio in canine and feline urine. METHODS: A complete urinalysis, including sulfosalicylic acid (SSA) precipitation, was performed on urine samples submitted to our laboratory between February and April 2003 from 100 dogs and 49 cats. Urine protein and creatinine concentrations were determined by the Multistix PRO dipstick using a Clinitek 50 analyzer (Bayer) and compared with the results of SSA precipitation and quantitative biochemical analysis. The UP:UC ratios from the dipstick results (calculated by the Clinitek 50 and also manually) were compared with those calculated from quantitative values. Pearson product-moment correlation analysis and diagnostic sensitivity and specificity (using quantitative results as the gold standard) were determined. RESULTS: For both canine and feline urine, protein and creatinine concentrations determined by the Multistix PRO correlated closely with quantitative concentrations for protein (dogs r = .78, P = .0001; cats r = .87, P = .0001) and creatinine (dogs r = .78, P = .0001; cats r = .76, P = .0001). The Multistix PRO was more sensitive and less specific than SSA precipitation for diagnosing clinically significant proteinuria. UP:UC ratios obtained by manual calculation of dipstick results correlated best with quantitative UP:UC ratios in dogs, and had higher specificity but lower sensitivity for the diagnosis of proteinuria. In cats, UP:UC ratios determined by the dipstick method did not correlate (r = -.24, P = .0974) with quantitative values. CONCLUSIONS: The Multistix PRO, with manual calculation of UP:UC, may be a good alternative for the diagnosis of clinically significant proteinuria in dogs, but not cats. Dipstick creatinine concentration should be considered as an estimate.     

Evaluation the Clinitek status™ automated dipstick analysis device for semiquantitative testing of canine urine

The aim of this prospective study was to evaluate the Clinitek status™ analyser using Multistix10SG™/Microalbustix™ dipsticks (all: Siemens Dx) for canine urine (n = 101) compared to reference methods: visual reading (Combur9 dipstick, Roche), refractometry, microscopy, and quantitative protein/creatinine analysis (Pentra400, AxonLab). The automated analyses were done twice and visual tests were performed by two examiners.An excellent to good concordance was demonstrated between the first/second analysis with the Multistix10SG and the Combur9 dipstick, respectively with Cohen’s κ-values ranging from 0.776 to 1.000. Agreement between both dipsticks was good for glucose (κ = 0.753), blood (κ = 0.793), protein (κ = 0.788), and moderate for bilirubin (κ = 0.431) and ketones (κ = 0.540). In 6/101 specimens, false positive ketone reactions were obtained with the Multistix10SG™. Multistix10SG™ could not be used for determination of pyuria or specific gravity. Semiquantitative/quantitative protein results correlated well (ρ = 0.90) and creatinine measurements moderately (ρ = 0.76). Due to automated data transmission to the laboratory information system, the Clinitek status™ is of advantage in veterinary laboratories/clinics.     

Evaluating the use of plasma hematocrit samples to detect ketones utilizing urine dipstick colorimetric methodology in diabetic dogs and cats

Objective: To determine whether plasma from a heparinized hematocrit tube placed on a urine dipstick would accurately reflect (positive or negative) urine ketone results in diabetic dogs and cats. Design: Prospective study, 37 dogs and 43 cats, with a known history of diabetes or hyperglycemia, glucosuria, and symptoms of undiagnosed diabetes mellitus were tested. Setting: Veterinary Referral Hospital. Animals: Client owned dogs and cats. Interventions: None. Measurement and main results: Heparinized plasma and urine ketone results were recorded using urine reagent strips. Plasma dipstick results were compared to urine dipstick results as the standard. Results were recorded based on the color chart provided by the manufacturer. Two individuals were responsible for verifying the results of the colorimetric test. Test efficiency was 97% (sensitivity = 96%, specificity = 100%) for the canine population, 93% (sensitivity = 100%, specificity = 83%) for the feline population, and 95% (sensitivity = 98%, specificity = 91%) for the total population. Four of 80 animals were found to have discordant results (1 dog and 3 cats). Conclusion: Plasma from heparinized hematocrit tubes is clinically useful for detecting the presence or absence of ketonuria, and therefore ketosis, in diabetic dogs and cats using urine dipstick colorimetric methodology.     

Comparison of urine and blood as a convenient and practical sample for estimating the contamination level of live cattle with radioactive cesium

Blood and urine were compared to clarify which is a better sample for estimating the concentration of radioactive cesium in muscles of live cattle. The most probable concentration of ¹³⁷Cs in muscles was 21.0 times that in blood, and the error of this estimation was 28%. The concentration of ¹³⁷Cs in blood was estimated accurately using urine samples. The estimation error did not increase so much (33%), even when the concentration of ¹³⁷Cs in muscles was estimated using urine samples. On the other hand, the maximum volume of blood that can be collected with one syringe is 50 ml, whereas it is easy to collect 1,000 ml of urine. It took at least 360 min to confirm that a cow meets the legal standard by inspecting 50 ml of blood. However, with 1,000 ml of urine, a 20 min measurement time was sufficient for this purpose. This difference in the required measurement time is critically important for practical use. In addition, urine can be collected by farmers themselves, whereas the blood collection requires a veterinarian. Therefore, urine is a more convenient and practical sample for estimating the contamination level of live cattle with radioactive cesium.     

Estimating energy losses with urine in the cat

Urinary energy losses in cats have to be determined in energy balance trials as well as for the calculation of the metabolizable energy (ME) content of cat food. The aim of the present study was: first, to assess whether the energy content of cat urine quantified by bomb calorimetry differs from that quantified using GE (kJ) urine = 33 kJ × g C urine + 9 kJ × g N urine and investigate whether this difference could be attributed to influences of diets. Second, to assess whether the subtraction of 3.1 kJ/g of protein intake used for estimation of metabolizable energy content of cat foods is confirmed as usable. Data from 27 energy and protein balance trials from different studies with complete sampling of urine and faeces (29 cats in part A and 35 cats in part B) were used. Gross energy, carbon and nitrogen were determined in food, faeces and urine. Gross energy values in urine tended to be higher when determined with the formula of Hoffman and Klein compared to bomb calorimetry. The average relative difference of gross energy values between the methods was 18.8%. The mean energy loss in kJ/g of protein intake resulted in 3.7 kJ/g protein intake, which was not statistically significantly different (p = 0.12) from the tested value of 3.1 kJ/g of protein intake. In conclusion, the formula of Hoffman and Klein is not appropriate for the estimation of energy in cat urine. In balance studies, it is advisable to quantify the urinary energy content by bomb calorimetry. In the second part of the study, the protein correction factor to determine ME of 3.1 kJ/g protein intake for urinary energy losses of Kienzle et al. could be confirmed.     

Comparison of home monitoring methods for feline urine pH measurement

Background — Monitoring of urine pH, often done in the patient's home, is essential for proper clinical treatment and management of conditions such as urolithiasis. Objective — The purpose of this study was to assess the agreement in pH readings between a standard laboratory method and methods readily available for home monitoring. The influence of refrigerated storage on urine pH was also examined. Methods — Urine samples were obtained by cystocentesis from 40 clinically healthy cats, and pH was measured within 2 hours of collection. Each sample was evaluated using pH paper, urinalysis reagent strip, 2 brands of portable pH meters (Chek‐Mite, Corning, Corning, NY, USA; and Checker 1, Hanna Instruments, Woonsocket, RI, USA), and a standard laboratory benchtop pH meter. Urine samples were refrigerated, and a second pH reading was obtained with the laboratory benchtop meter after 24 hours. The degree of agreement was assessed among the different methods, with the laboratory benchtop pH meter as the reference method. Results — The closest agreement was obtained with the Chek‐Mite portable pH meter and least agreement with the Checker 1 portable pH meter, which had a constant negative bias of 0.31 units due to expiration of the electrode. As expected, pH paper and reagent strips had poor and intermediate agreement, respectively. The reagent strip method had a negative bias of 0.12 units when compared with the benchtop pH meter and wide disagreement at the low pH end. The reagent strip did not agree strongly with the reference method; only 50% of values were within 0.25 pH units of each other. The difference in pH between 0 hours (6.57 ± 0.54) and 24 hours of refrigeration (6.61 ± 0.53) was not considered clinically significant. Conclusion — Portable pH meters are excellent for monitoring urine pH at home as long as attention is given to electrode maintenance. Urine can be collected at home and kept refrigerated, and pH may be measured reliably within 24 hours using the reference method or a portable pH meter.     

Sensitivity of routine tests for urine protein to hemoglobin

Increasing concentrations of canine hemoglobin were added to aliquots of urine and saline to determine the relative sensitivity of several hemoglobin and protein detection methods including commercial reagent strips and sulfosalicylic acid. The hemoglobin detection pads of the reagent strips were 50 times more sensitive than the protein detection pads, indicating the presence of hemoglobin at a concentration of 0.001 g/L whereas the protein pads did not react positively unless the hemoglobin concentration exceeded 0.05 g/L. The sulfosalicylic acid test was the least sensitive, detecting hemoglobin only at concentrations of 0.4 g/L or higher. These results were similar for hemoglobin added either in the form of lysed red blood cells, intact red blood cells or associated with plasma proteins in whole blood.

It was shown that a urine hemoglobin concentration eliciting less than the maximal score on the hemoglobin detection pad will not be detected as “protein” either with the commercial urinalysis strips or with sulfosalicylic acid. It was also seen that hemoglobin becomes visible as a red pigment when exceeding 0.3-0.5 g/L in a clear, light urine. It follows that a positive urine protein reading in the presence of a positive but less than maximal hemoglobin score or a protein reading exceeding 1.0 g/L in a nonpigmented urine indicates “true” proteinuria in excess of hemoglobin and plasma proteins associated with urinary tract hemorrhage.

     

Estimating purine derivatives and nitrogen compound excretion using total urine collection or spot urine samples in grazing heifers

The study aimed to evaluate the excretion of purine derivatives (PDs) and nitrogen compounds (NCs) and their ratios with creatinine in supplemented Zebu heifers kept on pastures by comparing total urine collection and spot sampling. Five Nelore heifers (400 ± 15 kg) were used in a 5 × 5 Latin square design. The treatments were the amount of concentrate (220 g of crude protein/kg dry matter) offered (0, 3, 6, 9 and 12 g/kg BW). In each period, the total urine collection was performed continuously for 3 days (subsampled at intervals of 4 h, 00:00–04:00 h, 04:00–08:00 h, 08:00–12:00 h, 12:00–16:00 h, 16:00–20:00 h and 20:00–24:00 h). The spot urine samplings were performed (in each period) for 24 h (0, 4, 8, 12, 16 and 20 h). Creatinine, total urinary nitrogen (UN), urea nitrogen (UreaN), allantoin and uric acid were analysed. Creatinine excretion was 23.01 ± 0.19 mg/kg BW and was not affected by collection day, treatment or their interactions (p > 0.05). Treatments affected (p < 0.05) PD excretions, however did not affect the ratio PD:creatinine (p > 0.05). Treatments and collection time affected (p < 0.05) NC excretion, whereas the UN:creatinine and UreaN:creatinine ratios were not affected (p > 0.05). Creatinine excretion and the PD:creatinine ratios in the urine samples estimated by the total or spot sampling were not different (p > 0.05). However, sampling method affected (p < 0.05) the UN:creatinine and UreaN:creatinine (p < 0.05) ratios. Creatinine can adequately estimate urinary excretion in grazing heifers, and a single spot urine sample at any time of the day can be used to estimate PD excretion in grazing heifers. But two spot urine samples are needed for proper NC excretion estimations in grazing heifers’ urine.     

The effect of urine acidification on calcium oxalate relative supersaturation in cats

There is an apparent reciprocal relationship between magnesium ammonium phosphate (MAP, struvite) and calcium oxalate (CaOx) urolithiasis incidence rate in cats. The number of struvite uroliths submitted for analysis over the past 35 years has been decreasing, with an increase in CaOx urolith submissions. Commercial diets aimed to dissolve struvite uroliths are typically acidified, and it has been suggested that dietary acidification increases urinary calcium excretion and the risk of CaOx crystallization. The objective of this study was to assess the effect of urine acidification on the relative supersaturation (RSS) of CaOx in cats, as a representation of crystallization risk. Four diets were extruded to contain identical nutrient contents, but with gradual acidification (0, 0.6, 1.3 and 1.9% sodium bisulphate substituted sodium chloride in diets A, B, C and D respectively). Thirteen adult cats were fed each diet sequentially for a minimum of 10 days. Average urine pH was 6.4, 6.2, 6.0 and 5.9 on diets A, B, C and D respectively (p < 0.0001). Struvite RSS decreased on diets inducing more acidic urine pH (p < 0.0001). Urinary calcium excretion and concentration increased with diets inducing lower urine pH (p < 0.0001), but oxalate excretion and concentration decreased (p < 0.001). CaOx RSS was not different between diets (p = 0.63). These results suggest that a lower diet base excess and resulting urine pH to support struvite dissolution do not increase the risk for CaOx crystallization in the range of urine pH representative of most commercial feline diets. Long-term studies are needed to confirm this.     

Variation of pesticide concentration in sheep dips operated according to traditional and revised methods

OBJECTIVE: To quantify stripping in traditional dipping operations and to revise dipping methods, based on prediction of stripping so that a more stable concentration of pesticide in the dipwash is achieved. DESIGN AND METHODS: Plunge and shower dips were operated sequentially according to traditional and revised dipping instructions. Dips were operated by continuous and intermittent replenishment. Samples of mixed dipwash were collected periodically and assayed for pesticide (diazinon) concentration. RESULTS: Diagrammatic representations of pesticide concentration versus number of sheep dipped indicated traditional dipping leads to wide variations in the concentration of pesticide in dipwash during dipping. Intermittent replenishment led to a 'saw-tooth' pattern in the pesticide concentration. Traditional continuous replenishment (using the starting concentration of pesticide) indicated both the rate and extent of stripping was higher in shower dipping. If sufficient sheep were dipped, equilibrium was reached between the rate of pesticide replenishment and removal. An alternative method of dip operation by continuous replenishment, using a low starting concentration of pesticide and a replenishment concentration high enough to offset the pesticide loss through stripping resulted in a more stable concentration of pesticide in the dip. CONCLUSION: Revision of dipping instructions can lead to exposure of sheep to stable concentrations of stripping pesticide during dipping.     

Urine protein determination in dogs and cats: comparison of dipstick and sulfasalicylic acid procedures

Protein levels in urine specimens from 91 dogs and 65 cats were evaluated by sulfasalicylic acid precipitation (SSA) and dipstick methods. The dipstick frequently yielded reactions for protein that were greater than the level of protein indicated by SSA (i.e., false positive reactions), although no false negative reactions for protein were noted. All urine specimens with protein levels equal to or greater than 100 mg/dl by SSA had dipstick results of 3 +. Results of this study suggest that dipstick analysis for urine protein is an adequate screening procedure for the selection of urines for quantitative analysis of protein and creatinine to assess proteinuria.     

敖汉苜蓿硬实种子处理方法研究

试验以2002年收获的敖汉苜蓿种子为材料,采用不同水温浸种、98％浓硫酸不同浸种时间和石英砂磨破种皮等处理来研究打破敖汉苜蓿种子硬实的效果。结果表明,浓硫酸浸种处理中效果最佳的是浸种60 min,平均发芽率达到99％;不同水温浸种处理中效果最佳的是75℃的热水处理,平均发芽率达到79％。3种处理中以98％浓硫酸浸种60 min的效果最好,其次是石英砂磨破种皮,而各种水温浸种的效果较差。     

Evaluation of a commercial in-house test kit for the semi-quantitative assessment of microalbuminuria in cats

Proteinuria was assessed in 100 randomly selected sick cats and 22 healthy cats by means of the urine protein:creatinine ratio, a traditional urine "dipstick" and a commercial ELISA-based dipstick designed to detect microalbuminuria (MA) semi-quantitatively. In addition the repeatability and reproducibility of the MA test was assessed by comparing results of five replicate tests of 26 urine samples, interpreted by two different readers. Discrepancies existed in the replicate test result in 23 and 27% of the samples examined by reader 1 and 2, respectively, and on several occasions this discrepancy was between whether the sample was "positive" or "negative" for MA. The inter-reader agreement was good (kappa=0.75), but again discrepancies were noted and part of the reason for these problems appeared to be the necessary subjectivity in the interpretation of colour changes when reading test results. Proteinuria was significantly (P< or =0.014) more prevalent in the sick than the healthy cats with 36 and 9%, respectively, having detectable MA, 34 and 5%, respectively, having a urine protein to creatinine (UPC) ratio >0.5, and 84 and 9%, respectively, having positive urine protein dipstick analysis. There was a moderate significant correlation between UPC ratio and MA concentrations (r(s)=0.68, P<0.0001). While 13/87 cats with a UPC ratio < or =0.5 had positive MA results, 10/84 cats with negative MA results had a UPC ratio >0.5, and none of these had evidence of lower urinary tract disease. This study confirmed that MA and proteinuria are commonly seen in cats with a variety of diseases, but they are not necessarily both elevated, and the UPC ratio can be elevated without an increase in MA results. Furthermore, some repeatability problems were demonstrated with the semi-quantitative MA test. These findings demonstrate that the semi-quantitative MA test should not be relied on as the sole determinant of proteinuria.     

Preincubation dipping of turkey hatching eggs. I. Effect of shell treatment on amount and variability of fluid intake

Two techniques for egg-shell treatment were evaluated for their effects on the quantity and variability of the fluid absorbed by turkey hatching eggs subjected to the temperature-differential method of egg dipping. The use of pin or drill to pierce a uniform hole through the shell and membrane(s) on the large end of each egg caused a significant increase in the quantity of dip solution absorbed. Variability in fluid uptake by the eggs also was reduced significantly. Utilization of dilute acid to remove cuticle completely from the whole egg surface or partially from either end also had similar effects. The techniques described also permit and effective dipping procedure that does not require the preheating step.