NDT Advance Access originally published online on October 13, 2006
Nephrology Dialysis Transplantation 2006 21(12):3602-3603; doi:10.1093/ndt/gfl576
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Markers of bone turnover in haemodialysis patients
Email: alicja_grzegorzewska{at}yahoo.comSir,
I read with interest the article by Albalate et al. [1] on the association between phosphate removal and markers of bone turnover in haemodialysis patients. I would like to report our own experience with determination of osteoprotegerin (OPG)—receptor activator of nuclear factor (NF)-
B (RANK), its ligand (OPGL, RANKL) and other serum markers of bone metabolism and relate our results to those shown by Albalate et al. [1]. To my understanding, Dr Albalate is not familiar with our data.
In our uraemic patients treated with peritoneal dialysis (PD) or haemodialysis (HD), serum OPG level was higher than in controls. PD patients showed lower OPG level than HD ones [2–4]. OPG concentration was elevated in 92.7% of HD patients and in 51.7% of PD ones [2,4]. OPGL (RANKL) was in our study lower in HD patients than in controls [3,4]. The same pattern of changes was shown for the OPGL/OPG ratio [3,4].
Results of selected serum markers of bone metabolism, obtained in our dialysed patients and in those described by Albalate et al. [1], are shown in Table 1. Patients, presented by Albalate et al. [1], have higher serum OPG level and lower OPGL/OPG ratio as compared to our patients. These differences may be explained by serum concentration of parathyroid hormone (PTH) levels (intact PTH—iPTH, 1-84 PTH – CAP, 7-84 PTH – CIP). The lowest serum OPG levels and the highest OPGL/OPG ratios were shown in PD patients, having the lowest serum levels of PTH. In the whole group of our examined patients (PD and HD), serum OPG level correlated positively with iPTH (R = 0.374, P = 0.019), CAP (R = 0.366, P = 0.022) and CIP (R = 0.406, P = 0.010). Serum OPGL level correlated negatively with iPTH (R = –0.377, P = 0.018), CAP (R = –0.356, P = 0.026) and CIP (R = –0.383, P = 0.016); the same pattern of correlations was shown for the OPGL/OPG ratio (R = –0.435, P = 0.006 for iPTH; R = –0.414, P = 0.009 for CAP; and R = –0.440, P = 0.005 for CIP). From our results, we concluded that when serum PTH increases, OPG also rises to prevent bone destruction associated with PTH action [3].
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PD patients are more predisposed to adynamic bone disease (ABD) than HD ones [5]. We lean towards the hypothesis that a lower serum OPG level is connected with lower activity of osteoclasts, than that which appears in ABD [6] and with less compensating production of OPG [2]. Albalate et al. [1] have speculated that OPG increases in HD patients as a compensatory mechanism, in an attempt to compensate the enhanced resorptive activity in secondary hyperparathyroidism. This possible explanation is in agreement with our concept. However, when dialysed patients were separated using iPTH concentration below or over 100 pg/ml, there were no significant differences in serum OPG, OPGL and the OPGL/OPG ratio between both groups [7].
Albalate et al. [1] have found positive correlation of OPG and age in HD patients; in our study dialysed patients over 65 years had higher serum OPG level than those at an age less or equal to 65 years [8]. We think that an increase in serum OPG in older patients probably reflects a paracrine mechanism of bone cells to compensate for age-dependent bone loss.
Conflict of interest statement. None declared.
Chair and Department of
Nephrology
Transplantology
and Internal Diseases
Karol Marcinkowski University of
Medical Sciences
Pozna
Poland
References
- Albalate M, de la Piedra C, Fernandez C, et al. (2006) Association between phosphate removal and markers of bone turnover in haemodialysis patients. Nephrol Dial Transplant 21:1626–1632.
[Abstract/Free Full Text] - Grzegorzewska AE and M
ot M. (2004) Serum osteoprotegrin level is lower in peritoneal dialysis patients than hemodialysis ones. Ann Acad Med Bialostocensis 49:193–196.[Web of Science][Medline] - Grzegorzewska AE and Mot M. (2004) Ratio of cyclase activating and cyclase inactive parathormone (CAP/CIP) in dialysis patients: correlations with other markers of bone disease. Ann Acad Med Bialostocensis 49:190–192.
[Abstract/Free Full Text] - Grzegorzewska AE and Mot M. (2005) Using the ratio of serum osteoprotegerin ligand to osteoprotegerin to evaluate renal osteodystrophy in dialysis patients. Adv Perit Dial 21:188–193.[Medline]
- Weinreich T. (1998) Prevention of renal osteodystrophy in peritoneal dialysis. Kidney Int 54:2226–2233.[CrossRef][Web of Science][Medline]
- Coen G, Ballantini P, Balducci A, et al. (2002) Serum osteoprotegrin and renal osteodystrophy. Nephrol Dial Transplant 17:233–238.
[Abstract/Free Full Text] - Grzegorzewska AE and Mot M. (2006) Serum markers of bone turnover in dialyzed patients separated using intact parathormone level. Adv Perit Dial 22: (in press).[CrossRef][Web of Science][Medline]
- Grzegorzewska AE and Mot M. (2006) Serum markers of bone turnover in dialyzed patients separated according to age. Int Urol Nephrol 38:311–316.[CrossRef][Web of Science][Medline]
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