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Comparison of two methods of measuring the urinary protein concentration for the determination of the urinary protein to creatinine ratio in various animal species.
Abstract: Determination of the urinary protein-to-creatinine ratio (UPC) is an important tool in the quantification of proteinuria in animals. However, the result may be affected by the different methods of determining the urinary protein concentration. The aim of this study was to compare the turbidimetric method using benzethonium chloride and the colorimetric method using pyrogallol red in the measurement of the urinary protein concentration in dogs, cats, guinea pigs and horses. A total of 464, 192, 216 and 119 urine samples from dogs, cats, guinea pigs and horses were examined in the study, respectively. The group consisted of animals of both sexes and different ages, and, in the dogs and cats, it included both healthy animals and those with various health problems. In the group of horses and guinea pigs, only clinically healthy animals were included. A total of 347, 185, 103 and 100 samples from the dogs, cats, guinea pigs and horses were used in the statistical analysis; the other values were excluded as they were below the detection limit. According to the Passing-Bablok analysis, there was a significant constant and proportional difference in the horses. In the dogs, cats and guinea pigs, there was a significant constant difference, but no proportional difference. The Bland-Altman method showed significant bias between the two methods in the horses and cats, but not in the dogs and guinea pigs. In the dogs and cats, the agreement between the two methods was tested and expressed as Cohen's kappa (κ). In the cats, it was almost perfect for the proteinuric samples (κ = 0.823 3) and significant for the non-proteinuric samples (κ = 0.804 9). In the dogs, the agreement was significant for the non-proteinuric samples (κ = 0.621 5) and only moderate for the proteinuric samples (κ = 0.527 5). The influence of the method used to determine the urinary protein concentration should be taken into account when evaluating the UPC. Repeated examinations in one patient should be performed with the same method.
Copyright: © 2024 Kovarikova et al.
Publication Date: 2024-08-29 PubMed ID: 39296631PubMed Central: PMC11406498DOI: 10.17221/30/2024-VETMEDGoogle Scholar: Lookup The Equine Research Bank provides access to a large database of publicly available scientific literature. Inclusion in the Research Bank does not imply endorsement of study methods or findings by Mad Barn.
- Journal Article
Summary
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Overview
- This study compares two different laboratory methods for measuring urinary protein concentration to calculate the urinary protein-to-creatinine ratio (UPC) in several animal species.
- The aim was to determine how the choice of method affects UPC results in dogs, cats, guinea pigs, and horses, which is critical for diagnosing and monitoring proteinuria (excess protein in urine).
Background and Importance
- The urinary protein-to-creatinine ratio (UPC) is a key diagnostic measure used to quantify proteinuria in animals, which can indicate kidney disease or other health issues.
- Proteinuria assessment relies on accurately measuring urinary protein concentration along with creatinine concentration.
- Different laboratory techniques to measure urinary protein concentration may yield varying results, potentially affecting clinical decisions.
Study Objective
- To compare two specific methods of measuring urinary protein concentration:
- The turbidimetric method using benzethonium chloride.
- The colorimetric method using pyrogallol red.
- To evaluate the impact of these methods on UPC results across four animal species: dogs, cats, guinea pigs, and horses.
Study Design and Sample Collection
- Samples collected:
- Dogs: 464 urine samples.
- Cats: 192 urine samples.
- Guinea pigs: 216 urine samples.
- Horses: 119 urine samples.
- Demographics:
- Dogs and cats included both male and female animals of various ages and health statuses (healthy and with different health problems).
- Horses and guinea pigs included only clinically healthy animals.
- Some samples were excluded if values were below the detection limit, resulting in the following final numbers used for statistical analysis:
- Dogs: 347 samples.
- Cats: 185 samples.
- Guinea pigs: 103 samples.
- Horses: 100 samples.
Analytical Methods and Statistical Analysis
- Two statistical methods were used to compare measurements from the two protein determination techniques:
- Passing-Bablok regression: This method checks for constant and proportional differences between the methods.
- Bland-Altman analysis: This method assesses agreement and bias between the two measurement methods.
- Additionally, Cohen’s kappa (κ) statistic was used to evaluate agreement of proteinuria classification (proteinuric vs. non-proteinuric) between methods in dogs and cats.
Key Results
- Passing-Bablok analysis:
- In horses: Significant constant and proportional differences between methods.
- In dogs, cats, guinea pigs: Significant constant difference but no proportional difference.
- Bland-Altman analysis:
- Significant bias found between methods in horses and cats.
- No significant bias found in dogs and guinea pigs.
- Cohen’s kappa agreement for classification:
- Cats showed almost perfect agreement for proteinuric samples (κ = 0.8233) and strong agreement for non-proteinuric samples (κ = 0.8049).
- Dogs showed significant but lower agreement for non-proteinuric samples (κ = 0.6215) and only moderate agreement for proteinuric samples (κ = 0.5275).
Interpretation and Conclusions
- The study found that the method used to measure urinary protein concentration can cause differences in UPC results, especially in horses and cats.
- In dogs and guinea pigs, differences between methods were less pronounced, but some impact on results still exists.
- The classification of animals as proteinuric or non-proteinuric may vary depending on the measurement technique, especially in dogs where agreement was only moderate for proteinuric animals.
- Because of these differences, it is important to:
- Consider the measurement method used when interpreting UPC results clinically.
- Maintain consistency by using the same measurement method for repeated UPC assessments in individual patients to ensure comparability.
Cite This Article
APA
Kovarikova S, Blahova J, Vanova I, Marsalek P.
(2024).
Comparison of two methods of measuring the urinary protein concentration for the determination of the urinary protein to creatinine ratio in various animal species.
Vet Med (Praha), 69(8), 273-280.
https://doi.org/10.17221/30/2024-VETMED Publication
Researcher Affiliations
- Department of Animal Welfare and Protection and Veterinary Public Health, Faculty of Veterinary Hygiene and Ecology, University of Veterinary Sciences, Brno, Czech Republic.
- Department of Animal Welfare and Protection and Veterinary Public Health, Faculty of Veterinary Hygiene and Ecology, University of Veterinary Sciences, Brno, Czech Republic.
- Department of Physiology, Faculty of Veterinary Medicine, University of Veterinary Sciences, Brno, Czech Republic.
- Department of Animal Welfare and Protection and Veterinary Public Health, Faculty of Veterinary Hygiene and Ecology, University of Veterinary Sciences, Brno, Czech Republic.
Conflict of Interest Statement
The authors declare no conflict of interest.
References
This article includes 21 references
- Adams LG, Polzin DJ, Osborne CA, O’Brien TD. Correlation of urine protein/creatinine ratio and twenty-four-hour urinary protein excretion in normal cats and cats with surgically induced chronic renal failure.. J Vet Intern Med 1992 Jan-Feb;6(1):36-40.
- Cernochova H, Hundakova A, Bardi E, Knotek Z. Biochemical profile of urine in guinea pigs (Cavia porcellus).. Vet Med-Czech 2020 Oct;65(10):445-50.
- Crofton PM. Positive and negative interference in the benzethonium chloride method for urine protein.. Ann Clin Biochem 1989 Jan:26(Pt 1):104-5.
- Giraldi M, Rossi G, Bertazzolo W, Negri S, Paltrinieri S, Scarpa P. Evaluation of the analytical variability of urine protein-to-creatinine ratio in cats.. Vet Clin Pathol 2018 Sep;47(3):448-57.
- Grauer GF. Proteinuria: Measurement and interpretation.. Top Companion Anim Med 2011 Aug;26(3):121-7.
- Harley L, Langston C. Proteinuria in dogs and cats.. Can Vet J 2012 Jun;53(6):631-8.
- Hokamp JA, Nabity MB. Renal biomarkers in domestic species.. Vet Clin Pathol 2016 Mar;45(1):28-56.
- Jillings E, Squires RA, Azarpeykan S, Lopez-Villalobos N. Does blood contamination of urine compromise interpretation of the urine protein to creatinine ratio in dogs?. N Z Vet J 2019 Mar;67(2):74-8.
- Marshall T, Williams KM. Protein determination in cerebrospinal fluid by protein dye-binding assay.. Br J Biomed Sci 2000;57(4):281-6.
- McHugh ML. Interrater reliability: The kappa statistic.. Biochem Med (Zagreb) 2012;22(3):276-82.
- Monroe WE, Davenport DJ, Saunders GK. Twenty-four hour urinary protein loss in healthy cats and the urinary protein-creatinine ratio as an estimate.. Am J Vet Res 1989 Nov;50(11):1906-9.
- Mortier F, van Leeuwenberg R, Daminet S, Paepe D. Determination of age-specific reference intervals for selected serum and urinary biomarkers in elderly cats.. J Feline Med Surg 2023a Nov;25(11):1098612X231207492.
- Mortier F, Daminet S, Duchateau L, Demeyere K, Meyer E, Paepe D. Effect of laboratory and sample storage factors on urinary protein: Creatinine ratios and clinical decision making in cats.. J Vet Intern Med 2023b May-Jun;37(3):1038-46.
- Moyle PS, Specht A, Hill R. Effect of common storage temperatures and container types on urine protein: Creatinine ratios in urine samples of proteinuric dogs.. J Vet Intern Med 2018 Sep;32(5):1652-8.
- Rossi G, Bertazzolo W, Binnella M, Scarpa P, Paltrinieri S. Measurement of proteinuria in dogs: Analytic and diagnostic differences using 2 laboratory methods.. Vet Clin Pathol 2016 Sep;45(3):450-8.
- Surer H, Ozgun T, Yilmaz FM, Yilmaz G. The effect of centrifugation on three urine protein assays: Benzethonium chloride, benzalkonium chloride and pyrogallol red. Clin Chem Lab Med 2014 Apr;52(4):e71-3.
- Syme HM, Markwell PJ, Pfeiffer D, Elliott J. Survival of cats with naturally occurring chronic renal failure is related to severity of proteinuria. J Vet Intern Med 2006 May-Jun;20(3):528-35.
- Uberti B, Eberle DB, Pressler BM, Moore GE, Sojka JE. Determination of and correlation between urine protein excretion and urine protein-to-creatinine ratio values during a 24-hour period in healthy horses and ponies. Am J Vet Res 2009 Dec;70(12):1551-6.
- Vientos-Plotts AI, Behrend EN, Welles EG, Chew DJ, Gaillard PR, Busler JN, Lee HP. Effect of blood contamination on results of dipstick evaluation and urine protein-to-urine creatinine ratio for urine samples from dogs and cats. Am J Vet Res 2018 May;79(5):525-31.
- Watanabe N, Kamei S, Ohkubo A, Yamanaka M, Ohsawa S, Makino K, Tokuda K. Urinary protein as measured with a pyrogallol red-molybdate complex, manually and in a Hitachi 726 automated analyzer. Clin Chem 1986 Aug;32(8):1551-4.
- Yilmaz FM, Yilmaz G, Yucel D. Is secondary wavelength always necessary in turbidimetric urine protein measurements?. Clin Biochem 2008 May;41(7-8):645-7.
Citations
This article has been cited 1 times.- Kovarikova S, Blahova J, Steffenova V, Vaskova N, Jahn P. Exploratory Study of the Urine Protein-to-Creatinine Ratio in Apparently Healthy Horses.. Vet Sci 2025 Aug 21;12(8).
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