The long-term effect of serum magnesium on cyclosporin A toxicity
Email: keven{at}medicine.ankara.edu.tr
Sir,
We read with great interest the study by Holzmacher et al. [1], suggesting that low serum magnesium (Mg) levels caused a more rapid decline in allograft function and higher rates of allograft loss in patients with chronic cyclosporin A (CsA) toxicity. We would like to underline several points in this study:
- We were surprised by the dose of CsA reported in this paper, as it seems quite high at the time of biopsy, the mean 3.9±0.6 years and 4.3±0.7 years after transplantation, the mean dose of CsA 7.5±2.5 and 8.2±3.6 mg/kg/d for low Mg and the normal Mg groups, respectively, leading to high CsA levels for both groups. Such a high dose of CsA can induce chronic allograft nephropathy due to chronic CsA toxicity.
- The authors also reported that although the adjusted relative risk (RR) of graft loss was 35% higher in the low Mg in comparison to the normal Mg group, the RR was noted to be 0.65. By definiton, RR is a measure of how much a particular risk factor (patients with low Mg) influences the risk of a specified outcome (kidney failure/death). In this study by Holzmacher et al., according to an RR of 0.65, the low Mg group should have had lower death/kidney failure in comparison to the normal Mg group, as seen in Figure 2, bottom panel. In addition, the confidence interval for the RR was 0.41.4. It is clear that the confidence interval contains the value 1.0 and this is evidence that the RR is not statistically significant.
- The median level of CCR2 for the normal Mg group was not given and the mean level was given.
Conflict of Interest statement. None declared.
Kenan Keven1,
Ba
ol Canbakan1 and
Atilla H. Elhan2
1 Department of Nephrology2
Biostatistic Ankara
University School of Medicine
Ankara
Turkey
References
- Holzmacher R, Kendziorski C, Hofman RM, Jaffery J, Becker B, Djamali A. Low serum magnesium is associated with decreased graft survival in patients with chronic cyclosporin nephrotoxicity. Nephrol Dial Transplant 2005; 20: 14561462[Abstract/Free Full Text]