# Calciprotein particles in cats with naturally occurring chronic kidney disease

## TL;DR

This study explores calciprotein particles in cats with chronic kidney disease and their connection to mineral and bone disorders.

## Contribution

The study introduces a method to measure calciprotein particles in cats and links their levels to calcium trends and CKD-MBD.

## Key findings

- Preprandial T-CPP concentrations were associated with fibroblast growth factor-23 and parathyroid hormones.
- Postprandial T-CPP and L-CPP concentrations were significantly linked to phosphate levels.
- Cats with uptrend ionized calcium showed greater changes in T-CPP after dietary phosphate restriction.

## Abstract

Calciprotein particles (CPP) are nanoparticles that play an important role in the pathogenesis of chronic kidney disease-mineral and bone disorder (CKD-MBD).

Identification of plasma CPP and preliminary exploration of the relationships among CPP concentrations, calcification propensity (T50), and CKD-MBD variables in cats with azotemic CKD.

Cats with azotemic CKD (n = 52) stabilized on a phosphate-restricted diet (PRD).

Total CPP (T-CPP), low-density CPP (L-CPP), and high-density CPP (H-CPP) were measured in heparinized plasma using a fluorescent bisphosphonate (OsteoSense) after gel filtration. Standardized linear regression models evaluated associations among CPP, T50, and CKD-MBD variables. Generalized estimating equations compared preprandial and postprandial CPP concentrations. Calciprotein particle changes (ΔCPP) between visits were compared between cats with different ionized calcium (iCa) trajectories using independent samples t-test or Mann–Whitney U tests.

Fibroblast growth factor-23 (standardized coefficient [sβ], 0.35; P = .04) and parathyroid hormones (sβ, −0.34; P = .042) were significantly associated with preprandial T-CPP concentrations in cats fed a PRD, whereas phosphate was significantly associated with postprandial T-CPP (sβ, 0.72; P = .003) and L-CPP (sβ, 0.75; P = .003) concentrations before dietary phosphate restriction. ΔT-CPP was significantly greater in cats with CKD with uptrend iCa compared to those with downtrend iCa after PRD stabilization (14 105 ± 36 299 AU vs −29 495 ± 49 664 AU; P = .036).

Calciprotein particle measurement is possible in cats and adds to the assessment of CKD-MBD, particularly the risk of soft tissue mineralization. The trajectory of iCa after PRD might influence CPP concentrations in cats with CKD.