RESUMO
The increase of urinary fractional excretion of phosphorus (uFEP) may indicate phosphorus retention before the onset of hyperphosphatemia in the early stages of chronic kidney disease (CKD). The hypothesis of this study is whether uFEP may increase during the early stage of CKD as a compensatory mechanism to prevent hyperphosphatemia as well as whether hyperphosphatemia in the late stages is associated with increase or decrease in uFEP in dogs with naturally occurring CKD; therefore, the aim of this study was to determine the uFEP in CKD dogs with different stages. Forty-nine CKD dogs were included, and they were divided into stage 1 (serum creatinine < 1.4 mg/dL), stage 2 (serum creatinine 1.5 to 2.0 mg/dL), stage 3 (serum creatinine 2.1 to 5.0 mg/dL) and stage 4 (serum creatinine > 5.0 mg/dL), according to the IRIS staging criteria. The stage 3 was subdivided into stage 3-A (serum creatinine 2.1 to 3.5 mg/dL) and stage 3-B (serum creatinine 3.6 to 5.0 mg/dL). The control group comprised 10 dogs, and uFEP ≤ 40% was considered as normal. A progressive increase in uFEP along the progression of CKD was found. However, similar results of uFEP levels were observed in late CKD, since there were no differences between stages 3 (A, B) and 4. Interestingly, some CKD dogs with stage 4 showed normal or reduced uFEP, besides hyperphosphatemia; conversely, some dogs in early CKD had increased uFEP values and normophosphatemia. Our findings suggest that uFEP may act as a compensatory mechanism to avoid the onset of hyperphosphatemia in early CKD, but not in later stages. uFEP assessment may be considered as an additional tool for the diagnostic and monitoring of phosphate disorders in dogs with CKD, since it may help to identify disturbances of phosphorus balance. More studies are needed to elucidate the role of uFEP in phosphorus homeostasis in dogs with CKD.
RESUMO
Foi proposta uma revisão das terminologias empregadas para a descrição das alterações renais e também sugerida uma classificação em estágios para a doença renal crônica à semelhança da medicina humana pela IRIS (International Renal Interest Society). Essa classificação considera os estágios da doença de acordo com o tempo de evolução e a presença de marcadores de lesão renal. O objetivo principal é auxiliar no estabelecimento do diagnóstico, do prognóstico e da terapia adequada conforme cada estágio e, assim, retardar a perda da função dos rins e a evolução da doença renal e, dessa forma, propiciar melhor qualidade de vida ao paciente.
A terminology review was proposed in order to describe renal alterations as well as to suggest a classification according to the stages of chronic kidney disease by IRIS (International Renal Interest Society) which is similar to human medicine. That classification considers the stage of evolution of the disease and urinary markers of kidney damage findings. The main objective is to help to establish the diagnostic, the prognosis and the adequate therapy corresponding to each stage of the disease in order to delay loss of renal function and its progression, and then providing better quality of patient´s life.
