Biological impact of targeted dialysate calcium changes in haemodialysis patients: the key role of parathyroid hormone

Background. Establishing an optimal dialysate calcium (DCa) concentration in haemodialysis patients is crucial. DCa individualization has been advocated but most dialysis centres use a fixed DCa, preferably 1.25 mmol/L in the USA and 1.5 mmol/L in European countries. The aim of the study was to assess the short-term biological impact of individual DCa prescription aiming at maintaining normal serum calcium and serum parathyroid hormone (PTH) between 150 and 300 pg/mL. Methods. Between January 2008 and December 2010, all prevalent patients were checked for the need for DCa change according to our usual strategy Baseline (TO) and after 3 months (T3), values were compared for serum calcium, phosphate, total alkaline phosphatases (t-ALP) and PTH. Results. Seventy-eight patients were followed up for analysis with only one DCa change. Vitamin D derivatives, oral calcium and cinacalcet doses remained stable. Increasing DCa from 1.25 to 1.5 mmol/L and from 1.5 to 1.75 mmol/L led to a significant increase of calcaemia (+2.2 and +1.7%) and a decrease of phosphataemia (-7 and -9%), t-ALP (-10 and -12%) and PTH (-50 and -62%). Decreasing DCa from 1.75 to 1.5 mmoll/L and from 1.5 to 1.25 mmol/L led to a decrease of calcaemia (-2.5 and -1.7%) and an increase of phosphataemia (+11 and +12%), t-ALP (+12 and +10%) and PTH (+138 and +175%). Conclusions. DCa individualization has a significant impact on mineral metabolism parameters, especially on serum PTH levels, and could be considered as an additional therapy in a more global strategy together with phosphate binder, vitamin D and calcimimetics prescription.