Abstract: Abstract Target To compare the differences on calcium mass balance in maintenance hemodialysis patients treated by dialysates with different calcium concentration. Methods In a single hemodialysis center, 20 maintenance hemodialysis patients were rolled into the study randomly. Different calcium dialysates, 1.50mmol/L and 1.75mmol/L, were used for 20 patients in standard hemodialysis treatment for three times, respectively. The calcium mass transfer (CMT) during one hemodialysis session by using different calcium dialysates were calculated respectively. The calcium intake of diet and calcium binder was recorded. The calcium absorption from intestine (CaAbs) and calcium mass balance during 48 hours (CMB48h) was calculated. The relationships among CMT, CMB48h and other parameters were tested. Results There were no significant differences on total calcium mass transfer (tCMT) , CaAbs, and CMB48h between two different calcium dialysate treatments, 3.44±8.58（mmol） vs. 7.43±10.97（mmol）, P=0.256, 145.6±92.1（mg） vs. 146.3±92.7（mg）, P=0.388, 268.2±364.9（mg）vs. 443.4±438.1（mg）, P=0.215, respectively. The correlated factors of tCMT were spent dialysate volume and ΔtCaF-S, B = -1.50 and 120.24, respectively, P<0.001. The tCMT was the only correlated factor of CMB48h, B = 39.51, P<0.001. Conclusions The calcium mass transfers from dialysate to blood during hemodialysis treatment by using 1.50mmol/L and 1.75mmol/L calcium dialysates. The differences on tCMT between the different calcium dialysates therapy were no significant. The tCMT was the important factor for CMB48h. The tCMT during hemodialysis were affected by ultrafiltration volume and the calcium concentration of dialysate.

Key words: hemodialysis, dialysate, calcium mass balance, calcium mass transfer, ionized calcium