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Calcium and phosphate balance with quotidian hemodialysis
Robert M Lindsay1, Fayez Alhejaili, Gihad Nesrallah
1Optimal Dialysis Research Unit, London Health Sciences Centre, London, Ontario, Canada. robert.lindsay@lhsc.on.ca
Insights
Frequent hemodialysis (HD) improves mineral balance. Nocturnal HD offers superior phosphate control compared to daily HD, with benefits from adjusted dialysate calcium concentration.
Area of Science:
- Nephrology
- Mineral Metabolism
- Dialysis Therapy
Background:
- Conventional hemodialysis (HD) disrupts calcium and phosphate metabolism, leading to abnormal parathyroid hormone (PTH) levels.
- The impact of more frequent HD schedules on mineral balance remains unclear.
Purpose of the Study:
- To investigate the effects of quotidian hemodialysis (daily or nocturnal) on calcium and phosphate metabolism.
- To assess changes in bone alkaline phosphatase and intact parathyroid hormone (iPTH) levels with frequent HD.
Main Methods:
- The London Daily/Nocturnal Hemodialysis Study compared daily HD (n=11) and nocturnal HD (n=12) groups.
- Evaluated serum calcium, phosphate, bone alkaline phosphatase, and iPTH levels, alongside phosphate-binder use and calcium x phosphate product.
Main Results:
- Nocturnal HD patients demonstrated significantly lower predialysis phosphate levels and reduced phosphate-binder requirements compared to daily HD and conventional HD.
- Both quotidian HD groups showed decreased calcium x phosphate product, with nocturnal HD achieving significantly lower levels.
- Bone alkaline phosphatase increased slightly in both groups; adjustments to dialysate calcium concentration normalized PTH trends.
Conclusions:
- Nocturnal HD provides superior control of serum phosphate levels compared to daily and conventional HD.
- Increasing dialysate calcium concentration in slow nocturnal HD can effectively manage PTH and bone alkaline phosphatase levels.
Background:
Conventional hemodialysis (HD) is associated with profound disturbances in calcium and phosphate metabolism and abnormal parathyroid hormone (PTH) levels. Effects of more frequent HD on calcium and phosphate balance have not been fully elucidated.
Methods:
The London Daily/Nocturnal Hemodialysis Study examined effects of quotidian HD, either daily HD (n = 11) or nocturnal HD (n = 12), on calcium and phosphate metabolism, bone alkaline phosphatase levels, and intact PTH (iPTH) levels.
Results:
Daily HD patients showed a slight decrease in predialysis serum phosphate levels, no changes in phosphate-binder requirements or serum calcium levels, and slight increases in serum bone alkaline phosphatase and iPTH levels. Nocturnal HD patients showed a trend for decreased predialysis phosphate levels, with significantly lower values than daily HD and matched control patients on conventional HD therapy at several times. Phosphate-binder use by nocturnal HD patients was significantly reduced. Both quotidian HD groups showed decreases in calcium x phosphate product, with significantly lower values for nocturnal HD patients (38.11 mg(2)/dL(2)) compared with daily HD and control patients (53.99 and 52.51 mg(2)/dL(2), respectively) at 18 months. Bone alkaline phosphatase levels increased slightly and attained statistical significance compared with baseline values for both quotidian HD groups. A trend for increases in serum iPTH levels, coupled with increasing levels of bone alkaline phosphatase in nocturnal HD patients, led to the decision to increase the dialysate calcium concentration from 5.0 to 7.0 mg/dL. This 1-time adjustment resulted in a reversal of the trend and a return to baseline values.
Conclusion:
This study shows the superior control of serum phosphate levels in nocturnal HD patients compared with daily HD or conventional HD patients and the benefits of dialysate with a greater calcium concentration in slow nocturnal HD.