E-Poster Presentation ESA-SRB-ANZBMS 2021

Effect of nutritional calcium and phosphate loading on calciprotein particles (#765)

Mark K Tiong 1 2 , Michael MX Cai 1 , Nigel D Toussaint 1 2 , Sven-Jean Tan 1 2 , Edward R Smith 1 2
  1. Department of Nephrology, The Royal Melbourne Hospital, Parkville, VIC, Australia
  2. Department of Medicine (RMH), University of Melbourne, Parkville, VIC, Australia

Background: Calciprotein particles (CPP) are endogenous, colloidal aggregates of calcium and phosphate and the mineral-binding protein fetuin-A. Serum CPP have been reported to be elevated in multiple conditions, including chronic kidney disease (CKD), where levels are associated with increased cardiovascular risk. Dietary phosphate loading in rodents leads to increased circulating CPP levels, but the effect of nutritional loading in humans has not been previously described. 

Aim: To examine the effect of nutritional loading on serum CPP in participants with and without CKD.

Methods: Amorphous calcium phosphate containing primary CPP (CPP-I) and hydroxyapatite-containing secondary (CPP-II) were measured by flow cytometry in 14 patients with CKD (eGFR<60mL/min/1.73m2) and 16 age- and gender-matched healthy adults. Serum CPP were measured after an overnight fast and then at five timepoints after participants received a standardised meal (Sanitarium Up&Go; 250mL, containing 300mg calcium [38% RDI] and 188mg phosphate [19% RDI]). Linear mixed effects models were fitted to examine differences between groups at each timepoint, and to estimate the postprandial excursion of serum CPP from baseline values.

Results: Mean age of the cohort was 44 years and 57% were female. The median eGFR of the CKD cohort was 28.5mL/min/1.73m2 (range 10-51mL/min/1.73m2). There were no between-group differences in serum CPP-I or CPP-II at any timepoint. The post-prandial excursion of serum CPP was subsequently examined after combining the groups (Table 1). Serum levels of CPP-I and CPP-II rose significantly after the standardised meal. Levels of both CPP-1 and CPP-II remained elevated from baseline values at four hours after the meal.

Conclusions: We found a significant acute post-prandial effect on serum CPP-I and CPP-II confirming dietary mineral as an important modifier of circulating CPP levels. In this small study, CKD did not significantly affect the post-prandial excursion of serum CPP.

 

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