The Effects of Nocturnal Compared with Conventional Hemodialysis on Mineral Metabolism: A Randomized-controlled Trial

Hyperphosphatemia is common among patients receiving dialysis and is associated with increased mortality. Nocturnal hemodialysis (NHD) is a long, slow dialytic modality that may improve hyperphosphatemia and disorders of mineral metabolism. We performed a randomized-controlled trial of NHD compared with conventional hemodialysis (CvHD); in this paper, we report detailed results of mineral metabolism outcomes. Prevalent patients were randomized to receive NHD 5 to 6 nights per week for 6to 10 hours per night or to continue CvHD thrice weekly for 6 months. Oral phosphate binders and vitamin D analogs were adjusted to maintain phosphate, calcium and parathyroid hormone (PTH) levels within recommended targets. Compared with CvHD patients, patients in the NHD group had a significant decrease in serum phosphate over the course of the study (0.49 mmol/L, 95% confidence interval 0.24-0.74; P=0.002) despite a significant reduction in the use of phosphate binders. Sixty-one percent of patients in the NHD group compared with 20% in the CvHD group had a decline in intact PTH (P=0.003). Nocturnal hemodialysis lowers serum phosphate, calcium-phosphate product and requirement for phosphate binders. The effects of NHD on PTH are variable. The impact of these changes on long-term cardiovascular and bone-related outcomes requires further investigation.