The ups and downs of dialysate calcium concentration in haemodialysis patients

Abstract

The absence of consensus on what should be the ideal dialysate calcium (DCa) concentration in haemodialysis patients is in part explained by the continuously changing therapeutic practice, but also on the scanty evidence that has been produced on this topic. The lack of consistent studies in this field is in part due to a number of methodological limitations for the assessment of both the global external and dialysis calcium balance. Some recent studies, one of which was published in the present issue of the NDT Journal, have added some important information in this field. The main aim of the present editorial is to comment on these recent contributions and also to focus on the foremost limitations and difficulties in the execution of calcium balance studies and their interpretation. The question of what should be the ideal dialysate calcium (DCa) concentration has troubled nephrologists from the earliest days of the dialysis history and still troubles them. The persistence of uncertainties concerning this issue is in part due to the continuously changing scenario in the therapeutic approach to the control of secondary hyperparathyroidism (SHP) and of the related mineral metabolism changes. In fact, at the very beginning of the dialysis history, a DCa close to the physiological concentration of ionized calcium (iCa) in the blood (1.25 mmol/ L) was used. At that time, no effective drug was available for the control of SHP and consequently hypocalcaemia and severe SHP were almost invariably observed. To overcome these problems, in the following years, a DCa of