Ionized calcium/total calcium ratio during biofiltration

The transmembrane transfer of calcium during hemodialysis is related to many factors (calcium gradient, plasma volume flow, plasma concentration of phosphate). During biofiltration the high ultrafiltration rate reduces the net transfer of calcium from dialysate to patient. Prolonged metabolic alkalosis occurs during biofiltration, lowering the ionized calcium/total calcium ratio. These two factors may stimulate PTH secretion, with negative long-term effects in dialysis bone disease.