Patients with end-stage renal disease (ESRD) who have elevated serum phosphate (P) levels have significantly higher mortality rates compared to those with normal P. In patients receiving conventional dialysis regimens, serum P may be lowered through dietary intervention and use of P binders, though these have potentially important side effects and may adversely impact quality of life. Whether lowering P, and / or targeting specific P levels improve survival and clinical outcomes is unknown. Despite this uncertainty, over 90% of patients with ESRD receive P lowering therapy and guidelines for the care of patients with ESRD are increasingly calling for more aggressive phosphate lowering. This intensive P lowering results in extra medications (and their associated side-effects), and higher health care costs. We are uncertain whether the intensification of P control results in measurable benefits to patients with ESRD. The overall goal of this pilot trial is to evaluate the feasibility of conducting a randomized controlled trial of intensive vs liberalized phosphate control among hemodialysis recipients.

Inclusion Criteria:

1. Age ≥ 18 yrs
2. Receiving chronic hemodialysis for > 90 days,
3. Dialysis prescription is currently no more than 4 sessions per week and prescribed as 3-5 hrs per session
4. Most recent P value 1.30-2.50 mmol/L
5. Receipt of a calcium-based P binder

Exclusion Criteria:

1. Patient is booked (with a known surgical date) for a live donor kidney transplant in the next 26 weeks
2. Planned switch to a dialysis schedule that involves > 16 hours per week of therapy within the next 26 weeks.
3. Planned switch to peritoneal dialysis within the next 26 weeks
4. Pregnancy
5. Albumin-corrected serum calcium > 2.60 mmol/L in the past year requiring reduction of the calcium carbonate dose
6. History of calciphylaxis
7. Attending nephrologist believes that an otherwise eligible patient is mandated- on clinical grounds- to have a P value that is targeted to < 1.50 mmol/L or > 2.00 mmol/L
8. Attending nephrologist believes an otherwise eligible patient is not a candidate for escalation of the current calcium dose
9. Co-enrollment in a clinical trial where the intervention is deemed to interfere with the adherence, safety or efficacy of the intervention provided herein