Phosphorus balance and mineral metabolism with 3 h daily hemodialysis

Poor control of mineral metabolism is independently associated with mortality in patients receiving hemodialysis. We analyzed data from a 12-month, prospective, non-randomized, controlled study of daily hemodialysis ( DHD) ( six sessions/ week 3 h each) ( n= 26) vs conventional hemodialysis ( CHD) ( three sessions/ week 4 h each) ( n= 51) for achievement of mineral metabolism goals and we performed a substudy of weekly dialytic phosphorus removal in DHD vs CHD. Phosphorus control was superior in the DHD group (% change from baseline to end-of-study - 27 +/- 30% vs +7%+/- 35% in the CHD group, P =0.0001). Percentage of patients using phosphate binders decreased from 77 to 40% among subjects on DHD, whereas these parameters did not change ( 76 vs 77%) in the CHD group ( P =0.03 by Breslow-Day test for homogeneity of the odds ratios). Weekly mean phosphorus removal was higher in the DHD group ( 2452 +/- 720mg/ week vs 1572 +/- 366mg/ week, P =0.04). Mean normalized protein catabolic rate increased ( 0.90 +/- 0.43 - 1.22 +/- 0.26 g/ kg/ day, P =0.0013). DHD was also associated with an increase in the percent of subjects achieving three or more mineral metabolism goals ( for phosphorus, calcium x phosphorus and parathyroid hormone) ( 15 vs 46%, P =0.046). In conclusion, DHD improves phosphorus control by increasing dialytic phosphorus removal while maintaining nutritional status and reducing the use of phosphate binders. The net effect allows for improved achievement of mineral metabolism goals.