Patients with end-stage kidney disease (ESKD) have an increased risk of cardiovascular mortality. High parathyroid hormone (PTH) from secondary hyperparathyroidism leads to increased efflux of phosphate and calcium from bone, which exacerbates vascular calcification and increases the risk of bone fractures. The main driving factor for secondary hyperparathyroidism is hypocalcaemia caused by low levels of 1,25-dihydroxy vitamin D and pharmacological supplementation with activated vitamin D and oral calcium-containing phosphate-binders are used to control secondary hyperparathyroidism. The amount of calcium used in this context is controversial, as higher calcium load in blood may theoretically increase vascular calcification. Conversely, by alleviating the efflux of phosphate and calcium from bone due to secondary hyperparathyroidism, increasing the load of calcium might actually prevent vascular calcification. To study this further, we wish to conduct a randomised double-blinded controlled clinical trial of increasing dialysate Ca from 1.25 mmol/L (standard dialysate concentration) to 1.50 mmol/L in patients with ESKD and secondary hyperparathyroidism on maintenance haemodialysis (HD). The overall effect of increased dialysate calcium will be gauged by its effect on serum calcification propensity (T50) and on markers of bone turnover.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
DOUBLE
Enrollment
48
Increased dialysate calcium of 1.50 mmol/L (as compared to standard dialysate calcium of 1.25 mmol/L)
Difference in serum calcification propensity (T50)
Between-groups difference in T50 at day 28 adjusted for T50 at day 0
Time frame: 28 days
Difference in bone-specific alkaline phosphatase (bALP)
Between-groups difference in bALP at day 28 adjusted for bALP at day 0
Time frame: 28 days
Difference in procollagen 1 intact N-terminal propeptide (P1NP)
Between-groups difference in P1NP at day 28 adjusted for P1NP at day 0
Time frame: 28 days
Difference in tartrate-resistant acid phosphatase 5b (TRAcP 5b)
Between-groups difference in TRAcP 5b at day 28 adjusted for TRAcP 5b at day 0
Time frame: 28 days
Difference in parathyroid hormone (PTH)
Between-groups difference in PTH at day 28 adjusted for PTH at day 0
Time frame: 28 days
Difference in calciprotein monomers (CPM)
Between-groups difference in CPM at day 28 adjusted for CPM at day 0
Time frame: 28 days
Difference in primary calciprotein particles (CPP-1)
Between-groups difference in CPP-1 at day 28 adjusted for CPP-1 at day 0
Time frame: 28 days
Difference in primary calciprotein particles (CPP-2)
Between-groups difference in CPP-2 at day 28 adjusted for CPP-2 at day 0
Time frame: 28 days
Difference in plasma ionised calcium (iCa)
Between-groups difference in iCa at day 28 adjusted for iCa at day 0
Time frame: 28 days
Difference in plasma phosphate (PO4)
Between-groups difference in PO4 at day 28 adjusted for PO4 at day 0
Time frame: 28 days
Difference in plasma magnesium (Mg)
Between-groups difference in Mg at day 28 adjusted for Mg at day 0
Time frame: 28 days
Difference in all above variables
Within-groups difference in all above variables at day 28 adjusted for values at day 0
Time frame: 28 days
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