CALCIUM MASS-BALANCE AND BEHAVIOR OF INTACT IMMUNOREACTIVE PARATHYROID-HORMONE IN ACETATE-FREE BIOFILTRATION - ACUTE AND ONE-YEAR EVALUATION

The present study evaluated calcium mass balance (MB) during acetate-f ree biofiltration (AFB) with a dialysate calcium concentration of 2 mm ol/l and different ultrafiltration rates (UF; 42.5 ml/min in schedule 1 and 48.5 ml/min in schedule 3), and with a calcium concentration of 1.75 mmol/l but an UF of 43 ml/min (schedule 2). We also examined the effects of these schedules on the behavior of intact parathryroid horm one (I-PTH). AFB according to schedule 1 and 3 achieve a positive calc ium MB (8.49 +/- 1.56 and 5.59 +/- 1.06 mmol, respectively), while in schedule 2 calcium MB merely balanced(0.07 +/- 2.29 mmol/l). A signifi cant acute intradialytic I-PTH decrease was observed with all schedule s; after 1 month, however, predialytic PTH values were unchanged in sc hedules 1 and 3, but worsening was noted in schedule 2. Subsequently, AFB was performed for 12 months employing a dialytic schedule (No. 1) involving a positive calcium balance. A year later I-PTH was significa ntly lower, thus proving that AFB may play an additional part in contr olling secondary hyperparathyroidism.