Validação da técnica imunoturbidimétrica para dosagem da Cistatina C e sua comparação com outros marcadores de injúria renal aguda em cães criticamente enfermos

Acute kidney injury (AKI) is a complex syndrome, associated with unfavorable evolution, especially in dogs in intensive care unit (ICU), which high morbidity and mortality. However, AKI effects can be minimized if diagnosed and treated early and adequately. AKI diagnosis requires combination of laboratory tests, which are considered to be non-sensitive and specific for the early detection of discrete degrees of loss of renal function. The biomarker cystatin C is considered superior to serum creatinine as it has better correlation with the glomerular filtration rate. However, there are no studies that demonstrated the use of cystatin C in dogs at ICU. The primary aim of this study was to validate the immunoturbidimetric technique (PETIA) to measure serum cystatin C in dogs. Commercially available method for human cystatin C (PETIA) was calibrated with canine cystatin C and resulted in a suitable calibration curve, with an average recovery of 97%. The reference range of serum cystatin C in healthy dogs was 0.57 mg / L - 1, 29 mg / L. No statistical differences among sex, age and weight were observed. The concentration of cystatin C in dogs with AKI was significantly higher (2.82 ± 1, 46 mg / L) than in control dogs (0.93 ± 0.18 mg / L). Statistical analysis of the data confirmed a strong correlation between cystatin C and serum creatinine (r = 0.94, p <0.05) in dogs with AKI. The second objective was to evaluate the performance of this biomarker in the diagnosis of AKI in dogs in ICU. Cystatin C concentration was determined in 28 dogs and compared with serum creatinine, IRIS classification and other laboratory tests. Serum cystatin C presented higher concentrations in 78.6% of dogs and most of them presented plasmatic creatinine level within the reference limits. The results demonstrate that cystatin C can be used for the detection of AKI in dogs in ICU, as it shows greater sensitivity when compared to traditional markers.