Haemodialysis session: The perfect storm for vascular calcification

Introduction: Vascular calcification (VC) associated to chronic kidney disease (CKD) is a complex phenomenon closely related to mineral bone metabolism disorders. Many are the factors implicated, as the drugs used in the treatment of CKD. Some in vitro studies suggest that electrolyte and acid–base disorders induced by haemodialysis (HD) may play a key role in VC. Methods: We analysed electrolyte and acid–base disorders that occur during an HD session in 26 patients randomly assigned to 1.25 mM or 1.5 mM calcium bath. Results: There is a calcium load in all the patients, independently of calcium bath concentration or basal serum calcium levels. At the end of the session, 100% of the patients dialysed with 1.5 mM calcium bath have calcium serum levels >1.3 mM. However, this only occurs in 15% of the patients dialysed with 1.25 mM calcium bath. During this calcium load, phosphorus levels persist uncontrolled. Besides, there is a progressive alkalinisation in all the patients. In the end of the session 50% have serum bicarbonate >30 mM and 23% pH >7.5. Conclusions: During HD sessions occur electrolyte and acid–base disorders that induce VC: calcium load and alkalisation in presence of elevated phosphorus levels. It is necessary to perform studies with kinetic models of calcium load and alkalinisation different from the actual ones.