M CONLEY1, K CAMPBELL1,2, C M HAWLEY1,2, N LIOUFAS3,4,5, G ELDER6,7,8, S V BADVE9,10, E PEDAGOGOS4,5, E M PASCOE2, A VALKS2, N D TOUSSAINT2,3
1Department of Nephrology, Princess Alexandra Hospital, Brisbane, Australia, 2Australasian Kidney Trials Network, The University of Queensland, Brisbane, Australia, 3Department of Nephrology, The Royal Melbourne Hospital, Parkville, Australia, 4Department of Medicine (RMH), University of Melbourne, Parkville, Australia, 5Western Health, Melbourne, Australia, 6University of Notre Dame, Sydney, Australia, 7University of Sydney, Sydney, Australia, 8Osteoporosis and Bone Biology Division, Garvan Institute of Medical Research, Darlinghurst, Australia, 9St. George Hospital, Sydney, Australia, 10Renal and Metabolic Division, the George Institute for Global Health, University of New South Wales, Sydney, Australia
Aim: To explore associations between dietary phosphate intake and biomarkers of mineral and bone metabolism and intermediate cardiovascular markers in a cohort of adults with stage 3-4b chronic kidney disease (CKD).
Background: Greater dietary phosphate intake is associated with increased adverse outcomes including cardiovascular disease (CVD). Abnormalities of bone and mineral metabolism in CKD, including higher serum phosphate, are important risk factors for increased CVD. Associations between dietary phosphate and biochemical and cardiovascular parameters in non-dialysis CKD patients however have not been adequately studied.
Methods: 132 of 278 participants enrolled in the IMPROVE-CKD trial were invited to participate in a dietary sub-study. Dietary phosphate intake was determined at baseline by a 7-day self-administered diet food record. Baseline clinical biomarkers of serum and urinary phosphate, serum calcium, parathyroid hormone (PTH), fibroblast growth factor-23 (FGF23) and intermediate cardiovascular markers (pulse wave velocity [PWV] and aortic calcification [AAC]) were correlated with dietary phosphate intake. Correlation analysis (Pearson’s and Spearman rank correlations) and linear regression analysis was undertaken to determine associations.
Results: 90 participants completed the sub-study (mean age 63.6±12.3 years, 68% male, mean eGFR 26.5±7.7ml/min/1.73m2, mean daily phosphate intake 1545±348 mg/day). There was no significant correlation between dietary phosphate intake and serum or urinary phosphate, serum calcium, PTH, FGF23, PWV or AAC. Multivariate linear regression also showed no association between dietary phosphate measurements and biochemical and cardiovascular parameters.
Conclusion: High levels of dietary phosphate were reported in this cohort, significantly above that which is recommended for patients with CKD. Measurements of dietary phosphate intake with a dietary food record however demonstrate no relationship with biochemical markers of bone and mineral metabolism or intermediate cardiovascular markers.
Marguerite is a senior renal and research dietitian at the Princess Alexandra Hospital in Brisbane Australia. Marguerite has 10 year’s experience working as a renal dietitian and is the current convener of the dietitians Australia renal interest group. Marguerite is has a special interest in nutritional management of renal transplantation and obesity management of CKD.