Evaluation of the analytical variability of urine protein‐to‐creatinine ratio in cats

Giraldi, Marco; Rossi, G.; Bertazzolo, Walter; Negri, Stefano; Paltrinieri, Saverio; Scarpa, P.

doi:10.1111/vcp.12646

Cited by 10 publications

(23 citation statements)

References 35 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…However, for the two differences in UPCs that fell outside the Bland–Altman plot LOAs, the absolute percentage changes of 6.62% and 14.71% are below the inter‐assay TE obs for high range UPCs of 18.87%, suggesting analytical variability alone could account for the differences in measurements observed in these samples. The calculated CV for the intra‐assay low‐range UPC of 5.9% was of a similar magnitude to the imprecision observed in a study by Giraldi and others 6 . The low‐range inter‐assay CV in this study of 29.4% was much higher than the 16.4% reported by Giraldi and others 6 .…”

Section: Discussionsupporting

confidence: 87%

See 1 more Smart Citation

The effect of non‐absorbent hydrophobic sand litter on the urine protein‐to‐creatinine ratio in feline urine

Kennils

Maunder

Costa

2022

Veterinary Clinical Pathol

View full text Add to dashboard Cite

Background Proteinuria can be quantified through the measurement of the urine protein‐to‐creatinine ratio (UPC). Voided urine samples in cats are often exposed to a non‐absorbable litter substrate prior to collection and urinalysis. Little is known about the effect exposure to such substrates has on pre‐analytical variability of UPC measurements. Objectives The aim of this study was to assess agreement between UPC measurements from urine obtained by cystocentesis before and after exposure to non‐absorbent hydrophobic sand for 24 hours. Methods UPCs were measured in 40 urine samples obtained by cystocentesis from 39 cats (baselineUPC). Urine was then exposed to non‐absorbent hydrophobic sand litter for 24 hours, recovered, and repeat UPCs were measured (litterUPC). Agreement between paired measurements and the presence of any bias or error was evaluated using Bland–Altman analysis Passing–Bablok regression analysis, respectively. Cohen's kappa was used to measure agreement for the International Renal Interest Society (IRIS) proteinuria classification of samples. Observed total error (TEobs) was calculated for the laboratory analyzer and compared against absolute percentage changes in paired UPC measurements. Results Neither proportional nor constant error was identified using Passing‐Bablok regression between baselineUPC and litterUPC. Visual inspection of the Bland–Altman plot revealed good agreement, with 95% of paired measures falling within the limits of agreement (LOA). Cohen's kappa demonstrated almost perfect agreement for the IRIS classification of proteinuria between baselineUPC and litterUPC. Absolute percentage changes of paired UPC measurements outside of the LOAs were lower than the inter‐assay TEobs. Conclusions Feline urine exposed to non‐absorbent hydrophobic sand litter appears acceptable for UPC measurements.

show abstract

Section: Discussionsupporting

confidence: 87%

“…The analytical variability for feline urinary protein concentration measurements has been shown to vary considerably depending on which measurement method was used 6 . The concept of total allowable error (TE a ) allows the assessment of analytical performance.…”

Section: Introductionmentioning

confidence: 99%

The effect of non‐absorbent hydrophobic sand litter on the urine protein‐to‐creatinine ratio in feline urine

Kennils

Maunder

Costa

2022

Veterinary Clinical Pathol

View full text Add to dashboard Cite

show abstract

“…The only two cases that showed a shift of the IRIS stage (from BP to NP and from NP to BP) had mean UPCs close to the cutoff of 0.2 (UPC = 0.22 and = 0.17); the recorded variability was interpreted as analytic inter-assay variability. 16 The procedure evaluated in this study did not consider many other possible variables occurring in daily practice scenarios. For example, feces or detergent contamination could occur and, in turn, affect urinalysis.…”

Section: Discussionmentioning

confidence: 99%

Influence of preanalytical factors on feline proteinuria

Giraldi

Paltrinieri

Rossi

et al. 2021

Veterinary Clinical Pathol

Self Cite

View full text Add to dashboard Cite

Background: To date, little information is available about the effect of preanalytical factors on the urinary protein-to-creatinine (UPC) ratio in cats.Objectives: We aimed to evaluate the effect of a commercially available cat litter, creatinine measurements at three different dilutions of urine, and different storage conditions on the UPC ratio in cats.Methods: Feline urine specimens were prospectively collected. Twenty-two wholeurine specimens were placed uncovered and in contact with cat litter for 1 hour; 25 urine supernatants were diluted 1:10, 1:20, and 1:100 for creatinine measurements.The correlation, difference, agreement, and concordance in classifying specimens according to International Renal Interest Society staging were determined. Storage effects on UPC ratios were assessed in specimens stored for 6 hours at +20℃ (n = 20), 1 week at +4℃ (n = 20), and 3 months at −20℃ (n = 25). Specimens were also subjected to four freeze-thaw cycles (n = 20). Results were compared, and clinical significance was assessed by comparing each UPC ratio to the inter-assay range of the baseline value.Results: Exposure to cat litter did not affect UPC ratios. A positive proportional bias was found in the 1:100 dilution compared with the 1:20 dilution; however, concordance was high for all comparisons. At +20, +4℃, and after four repeated freeze-thaw cycles, UPC ratios were stable. Compared with baseline values, UPC ratios decreased (P < .01) after 8 and 12 weeks at −20℃. However, all UPC ratios were within the inter-assay variability of the baseline value.Conclusions: Exposure to cat litter did not affect UPC ratios, but further studies are necessary to evaluate other potential variables. The effects of the dilutions and storage conditions were clinically acceptable, although the 1:20 and 1:100 dilutions were not perfectly comparable.

show abstract

“…This test has previously been shown to accurately reflect the degree of proteinuria in a 24‐hour period (Adams et al . 1992). In cats, different analytical methods are employed to determine UPC, the most common being the dye‐binding pyrogallol red‐molybdate and Coomassie brilliant blue methods (Giraldi et al . 2018). These methods are precise, but there is some disagreement between them, making the comparison amongst different laboratories questionable (Giraldi et al . 2018).…”

Section: Introductionmentioning

confidence: 99%

“…In cats, different analytical methods are employed to determine UPC, the most common being the dye‐binding pyrogallol red‐molybdate and Coomassie brilliant blue methods (Giraldi et al . 2018). These methods are precise, but there is some disagreement between them, making the comparison amongst different laboratories questionable (Giraldi et al . 2018). Moreover, UPC is usually measured in an external laboratory and does not allow patient‐side decision‐making, which reduces practicality and increases cost.…”

Section: Introductionmentioning

confidence: 99%

The utility of combined urine dipstick analysis and specific gravity measurement to determine feline proteinuria

Pérez-Accino

Bernabé²,

Manzanilla

et al. 2020

J of Small Animal Practice

View full text Add to dashboard Cite

Objectives To assess the utility of urine dipstick strips for detection of feline proteinuria when used in combination with urine‐specific gravity, compared with urine protein‐to‐creatinine ratio as the gold standard. Materials and Methods Retrospective analysis of clinical records of comprehensive urine examination obtained from cats presented to a referral hospital. Diagnostic agreement and test accuracy were calculated for the dipstick test alone and in combination with the urine‐specific gravity, using different cut‐off values for proteinuria. Receiver‐operating characteristic curves were also calculated. Results A total of 121 urine samples were included. The diagnostic agreement between dipstick and urine protein‐creatinine ratio was poor. A dipstick result of equal or greater than “Trace” (0.1–0.3 g/L) had a sensitivity of 81% and a specificity of 31% to detect proteinuria. Grouping the samples by urine‐specific gravity did not increase dipstick agreement with the urine protein‐creatinine ratio and only resulted in a slight improvement in the accuracy of detecting proteinuria. Clinical Significance The dipstick test was not accurate for detecting proteinuria when combined with urine‐specific gravity in cats. Clinicians should not rely on this test and, regardless of the urine concentration, other appropriate quantitative methods such as urine protein‐creatinine ratio should always be performed to detect proteinuria in cats.

show abstract

Evaluation of the analytical variability of urine protein‐to‐creatinine ratio in cats

Abstract: The two methods were precise, but the higher UPC ratios obtained with the CBB methods might affect the interpretation using the IRIS guidelines and clinical decisions.

Cited by 10 publications

References 35 publications

The effect of non‐absorbent hydrophobic sand litter on the urine protein‐to‐creatinine ratio in feline urine

The effect of non‐absorbent hydrophobic sand litter on the urine protein‐to‐creatinine ratio in feline urine

Influence of preanalytical factors on feline proteinuria

The utility of combined urine dipstick analysis and specific gravity measurement to determine feline proteinuria

Contact Info

Product

Resources

About