(NU16) A Pilot Study to Identify Plasma Calciprotein Particles in Cats with Chronic Kidney Disease

Abstract:

Background: Aggregation of fetuin-A with calcium-phosphate mineral allows calciprotein monomers (low-density calciprotein particles [L-CPP]) to form. Integration with further protein consolidates L-CPP to amorphous CPP which transform spontaneously into pro-inflammatory crystalline CPP over time (high-density CPP [H-CPP]).

Hypothesis/

Objectives: To identify different forms of CPP in feline plasma and evaluate their relationship with chronic kidney disease-mineral and bone disorder (CKD-MBD) parameters.

Animals: 15 euthyroid client-owned cats with International Renal Interest Society (IRIS) stage 2–3 azotaemic CKD.

Methods: Retrospective cross-sectional study. Frozen heparinized fasted plasma samples from CKD cats stabilised on a phosphate-restricted diet (constituting ≥90% of diet consumed) were selected for the identification and quantification of CPP. Total CPP (T-CPP), L-CPP and H-CPP were measured using an infrared fluorescent bisphosphonate (OsteoSense), in conjunction with a gel filtration method. Pearson correlation (r) was performed to evaluate the relationship of CPP with CKD-MBD parameters.

Results: Low-density CPP was identified as the predominant form of circulating CPP in feline plasma. Moderate to strong correlations were found among various forms of CPP (T-CPP, L-CPP and H-CPP) with total calcium (tCa), ionized calcium (iCa), calcium-phosphate product (CaPP) and fibroblast growth factor 23 (FGF23; Table 1); FGF23 was positively associated with tCa (r=0.8; p=0.005) and iCa (r=0.77; p=0.009).

Conclusions and clinical importance: Plasma tCa and iCa were found to be major predictors of CPP measured in fasted samples, supporting the importance of monitoring calcium status in CKD cats. The clinical implication and prognostic value associated with CPP in CKD cats remain to be investigated.