Urine protein, urine protein to creatinine ratio and N-acetyl-β-D-glucosaminidase index in cats with idiopathic cystitis vs healthy control cats.

Objectives The objective was to compare urine protein, urine protein to creatinine ratio (UPC) and N-acetyl-β-D-glucosaminidase (NAG) index between cats with idiopathic cystitis and clinically normal cats. Methods Urine and blood samples were collected from 19 clinically normal cats and 19 cats with idiopathic cystitis without azotaemia at the time of first presentation. Urine protein, urine creatinine and UPC were measured. Additionally, the urinary NAG concentration was measured using the colorimetric method, and the NAG index was calculated by dividing the urinary NAG concentration by the urine creatinine ratio. Results Urine protein concentration (mean ± SEM) was four times higher in cats with idiopathic cystitis (218.29 ± 58.95) than in clinically normal cats (56.13 ± 9.95) (P <0.05). The UPC (mean ± SEM) of cats with idiopathic cystitis (0.70 ± 0.19) was also five times higher than that of clinically normal cats (0.14 ± 0.02) (P <0.05). The mean ± SEM NAG index in cats with idiopathic cystitis (4.79 ± 1.53 U/g) was two times higher than that in clinically normal cats (2.14 ± 0.48 U/g). The log UPC was positively correlated with the log NAG index in cats with idiopathic cystitis at moderate levels (r2 = 0.512; P <0.05). Conclusions and relevance Cats with idiopathic cystitis had increased amounts of urine protein and an increased UPC. Further study is needed to address the role of urinary NAG and its relationship with glycosaminoglycan levels in cats with idiopathic cystitis.