Patients who undergo nocturnal hemodialysis (NHD) experience significant decreases in serum phosphate compared with patients on conventional hemodialysis (HD), despite a reduction in the use of phosphate binders, according to Canadian researchers.

In a six-month study, investigators at the University of Calgary and the University of Alberta randomized 26 patients to receive NHD (dialyzing six to 10 hours per night for five or six nights) and 25 patients to continue receiving conventional HD (dialyzing three times a week). The researchers, led by Michael Walsh, MD, of the University of Calgary, adjusted oral phosphate binders and vitamin D analogs to maintain phosphate, calcium, and parathyroid hormone (PTH) levels.

During the course of the study, serum phosphate levels decreased by a mean of 0.49 mmol/L in the NHD group compared with the conventional HD patients, the investigators reported in Hemodialysis International (published online ahead of print). Calcium-phosphate product decreased by a mean 1.1 mmol2/L2 in the NHD group compared with the conventional HD patients.

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Significant changes in PTH levels were common but were not strongly associated with NDH compared with conventional HD, the authors noted.

Although hyperphosphatemia is associated with an increased risk of death, the researchers pointed out that there is no evidence from randomized, controlled trials that improved phosphate control improves survival or health-related quality of life.

Dr. Walsh’s group observed no association between improved phosphate control and changes in  left ventricular mass or improved systolic BP.

The beneficial effects of NHD on serum phosphate levels and calcium-phosphate product raise the possibility that NHD may have a positive effect on cardiovascular health, the researchers stated, adding that their study was underpowered to determine important clinical events, including cardiovascular events.