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Abstract: TH-OR030

Multicentre Randomized Control Trial of Phosphate Control with a Modified as Compared to Standard Renal Diet

Session Information

Category: Bone and Mineral Metabolism

  • 402 Bone and Mineral Metabolism: Clinical

Authors

  • Byrne, Fiona Nora, Cork University Hospital, Cork, Cork, Ireland
  • Eustace, Joe, University College Cork, Cork , Cork, Ireland
  • Gillman, Barbara A., Mater Misericordiae University Hospital , Dublin, Ireland
Background

The standard renal diet fails to distinguish between phytate and non phytate bound phosphorus, despite consensus that the latter is poorly absorbed. A modified renal diet based on the increased use of pulses, nuts and whole grains, the avoidance of P additives and of over-prescription of protein may offer improved or similar [P] levels as the standard renal diet but with a wider food choice.

Methods

We conducted a national, multicentre, pragmatic, parallel arm, open label, randomized controlled trial (1:1 allocation ratio) of 1 month of modified vs. standard diet in 74 prevalent anuric adults on maintenance hemodialysis with a 3 mt mean pre-dialysis serum phosphate ([P]) >1.6mmol/L and a stable phosphate binder and vitamin D prescription. Subjects with a history of severe hyperkalemia, parathyroidectomy or recent acute illness were excluded. Subjects were re-educated on the standard diet or educated on the modified diet by the renal dietitian. Analysis was on a modified intention-to-treat basis of the difference between diets in follow-up [P] minus baseline [P] using an independent sample t test and a 2 sided type 1 error rate of 0.05.

Results

We recruited 74 subjects from 13 university dialysis units. Two patients did not have a follow-up [P], due to an insufficient sample and transplantation and thus could not contribute to the primary analysis. The study population was 96% Caucasian, 69% male, 36% of subjects had diabetes. Both diets were similarly well tolerated. The modified diet resulted in a significantly higher phytate and fiber intake (both p<0.01). Baseline and follow-up [P] in modified diet arm was 2.1 (0.5) and 2.0 (0.7) mmol/L, and in the Standard Diet arm were 2.0 (0.6) and 1.9 (0.6) mmol/l; the mean (95% CI) change in [PO4] in modified vs. standard arm was 0.01 (-0.24,0.21), p=0.91. The mean (sd) difference in follow-up [K] -baseline [K] in the modified and standard arms was 0.01 (0.7) and 0.09 (0.6) mmol/L respectively; the mean (95% CI) change in [K+] modified v standard was -0.07(-0.23,0.38), p = 0.63. C terminal FGF23 (n=27) was not significantly different. Limitations of this study include its modest sample size and limited intervention period.

Conclusion

The modified renal diet was well tolerated and was associated with similar [P] control but with a wider food choice and greater fiber intake than the standard diet.