Calcium phosphate metabolism and bone mineral density with nocturnal hemodialysis
- 23 June 2006
- journal article
- Published by Wiley in Hemodialysis International
- Vol. 10 (3), 280-286
- https://doi.org/10.1111/j.1542-4758.2006.00109.x
Abstract
An elevated calcium x phosphate product (Ca x P) is an independent risk factor for vascular calcification and cardiovascular death in dialysis patients. More physiological dialysis in patients undergoing nocturnal hemodialysis (NHD) has been shown to produce biochemical advantages compared with conventional hemodialysis (CHD) including superior phosphate (P) control. Benefits of dialysate with greater calcium (Ca) concentration are also reported in NHD to prevent Ca depletion and subsequent hyperparathyroidism, but there are concerns that a higher dialysate Ca concentration may contribute to raised serum Ca levels and greater Ca x P and vascular disease. The NHD program at our unit has been established for 4 years, and we retrospectively analyzed Ca and P metabolism in patients undergoing NHD (8-9 h/night, 6 nights/week). Our cohort consists of 11 patients, mean age 49.3 years, who had been on NHD for a minimum of 12 months, mean 34.3 months. Commencement was with low-flux (LF) NHD and 1.5 mmol/L Ca dialysate concentration, with conversion to high-flux (HF) dialyzers after a period (mean duration 18.7 months). We compared predialysis serum albumin, intact parathyroid hormone, P, total corrected Ca, and Ca x P at baseline on CHD, after conversion to LF NHD and during HF NHD. We also prospectively measured bone mineral density (BMD) on all patients entering the NHD program. Bone densitometry (DEXA) scans were performed at baseline (on CHD) and yearly after commencement of NHD. With the introduction of HF dialyzers, the Ca dialysate concentration was concurrently raised to 1.75 mmol/L after demonstration on DEXA scans of worsening osteopenia. Analysis of BMD, for all parameters, revealed a decrease over the first 12 to 24 months (N = 11). When the dialysate Ca bath was increased, the median T and Z scores subsequently increased (data at 3 years, N = 6). The mean predialysis P levels were significantly lower on LF NHD vs. CHD (1.51 vs. 1.77 mmol/L, p = 0.014), while on HF NHD P was lower again (1.33 mmol/L, p = 0.001 vs. CHD). Predialysis Ca levels decreased with conversion from CHD to LF NHD (2.58 vs. 2.47 mmol/L, p = 0.018) using a 1.5 mmol/L dialysate Ca concentration. The mean Ca x P on CHD was 4.56 compared with a significant reduction of 3.74 on LF NHD (p = 0.006) and 3.28 on HF NHD (p = 0.001 vs. CHD), despite the higher dialysate Ca in the latter. We conclude that an elevated dialysate Ca concentration is required to prevent osteopenia. With concerns that prolonged higher Ca levels contribute to increased cardiovascular mortality, the optimal Ca dialysate bath is still unknown. Better P control on NHD, however, reduces the overall Ca x P, despite the increased Ca concentration, therefore reducing the risk of vascular calcification.Keywords
This publication has 17 references indexed in Scilit:
- A systematic review of the effect of nocturnal hemodialysis on blood pressure, left ventricular hypertrophy, anemia, mineral metabolism, and health-related quality of lifeKidney International, 2005
- Calcium Loading, Calcium Accumulation, and Associated Cardiovascular Risks in Dialysis PatientsBlood Purification, 2005
- Resolution of massive uremic tumoral calcinosis with daily nocturnal home hemodialysisAmerican Journal of Kidney Diseases, 2003
- The Effect of Long Nocturnal Dialysis on Ca/Ph and Bone StatusHemodialysis International, 2003
- Estimating phosphate removal in haemodialysis: an additional tool to quantify dialysis doseNephrology Dialysis Transplantation, 2002
- Author IndexOto-Rhino-Laryngologia Nova, 2002
- Hemeral (Daily) HemodialysisAdvances in Renal Replacement Therapy, 2001
- Control of serum phosphate without any phosphate binders in patients treated with nocturnal hemodialysisKidney International, 1998
- Non-invasive measurements of bone mass in adult renal osteodystrophyBone, 1993
- Bone Mineral Density in Patients with End-Stage Renal FailureAmerican Journal of Nephrology, 1993