CORRECTION OF CHRONIC METABOLIC-ACIDOSIS IN HEMODIALYZED PATIENTS BY ACETATE-FREE BIOFILTRATION DOES NOT INFLUENCE PARATHYROID FUNCTION

In eight patients remaining acidotic after more than 1 year of bicarbo nate haemodialysis, we studied the effect of correcting the chronic me tabolic acidosis using acetate-free biofiltration for 4 months on the course of secondary hyperparathyroidism. An AN69 capillary membrane wa s employed with a bicarbonate infusion rate initially set at 1.8 1/h i n all patients and then adjusted in each one to obtain a predialysis b icarbonate of greater than or equal to 23 mmol/l. Standard blood chemi stry parameters were determined every 2 weeks. Measurements of PTH, ca lcifediol and calcitriol, as well as calcium-PTH curves were determine d at the beginning and end of the study. While acetate-free biofiltrat ion appears to be an adequate technique for the correction of chronic metabolic acidosis when bicarbonate dialysis fails, this study indicat es that it does not influence secondary hyperparathyroidism in haemodi alysed patients. The level of intact PTH did not vary significantly an d the calcium-PTH curves at 0 and 4 months were superimposable with no significant differences in the set point and the slope of the curves.