Prognostic role of the product of serum calcium and phosphorus concentrations in dogs with chronic kidney disease: 31 cases (2008-2010).

Abstract

To investigate serum calcium-phosphorus concentration product (sCaPP) as a predictor of mortality rate in dogs with chronic kidney disease (CKD). Retrospective case-control study. 31 dogs with definitive CKD and 35 apparently healthy dogs. All dogs had been referred for nephrological consultation between December 2008 and December 2010. Dogs with CKD had stable disease for ≥ 3 months. On the basis of glomerular filtration rate < 60 mL/min/m(2), 13 of the 35 apparently healthy dogs were subsequently classified as having early CKD. Disease stage among dogs was determined on the basis of plasma creatinine concentration as follows: stage 1, < 123.7 μmol/L (n = 13), stage 2, 123.7 to 176.8 μmol/L (7); stage 3, 185.6 to 442 μmol/L (13); or stage 4, > 442 μmol/L (11). For each dog, serum concentrations of ionized and total calcium and phosphorus were evaluated once; the latter 2 variables were used to determine sCaPP. The sCaPP differed significantly between the 22 healthy dogs and dogs with stage 3 or stage 4 CKD. The proportion of dogs with sCaPP > 70 mg(2)/dL(2) increased with stage of disease. Mortality rate among the 24 dogs with sCaPP > 70 mg(2)/dL(2) was higher than that among the 42 dogs with sCaPP ≤ 70 mg(2)/dL(2). Dogs with sCaPP > 70 mg(2)/dL(2) had a comparatively lower survival rate, and risk of death was 4.2 times as high as risk for dogs with sCaPP ≤ 70 mg(2)/dL(2). For dogs with CKD, sCaPP > 70 mg(2)/dL(2) appeared to be a negative prognostic indicator, which was not influenced by the concomitant serum concentrations of phosphorus and total or ionized calcium.